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departmentresearch group programmeprojectcoordinates)uuid:6cc7881f731b495287c2c7410a08ed52Dhttp://resolver.tudelft.nl/uuid:6cc7881f731b495287c2c7410a08ed52Generation and Evaluation of Truss Structures for the StrutandTie Model. Based on Topology Optimization Results for Deep Concrete BeamsEArgudo Sanchez, Geovanny (TU Delft Civil Engineering and Geosciences)Hendriks, Max (mentor); Lukovic, Mladena (graduation committee); Xia, Yi (graduation committee); Houben, Lambert (graduation committee); Delft University of Technology (degree granting institution)The StrutandTie model (STM) is an efficient technique for the design of concrete structures, but the creation of suitable truss structures gets complicated when these structures become more complex. The topology optimization (TO) is a convenient technique that has been used in recent years for the creation of trusses of complex structures for the STM. This thesis presents a process for the creation of suitable truss structures for the STM using the results obtained with the TO, as well as, an evaluation of them to see which is the most optimal truss structure according to the total amount of tension force present on the full truss, this total amount of tension force is the selected evaluation criterion. Three deep concrete beams were analyzed using two topology optimization (SIMP and BESO approaches) for the generation of stress paths, these approaches are based on the minimization of the strain energy. The procedure starts with the computation of the principal stresses over the results of the topology optimization, then bar elements are placed over the stress paths of these diagrams creating a first (harsh) layout of the trusses. These trusses were not always found stable, but all the trusses were stabilized because, in this way, it is easy to calculate the axial force of in the truss elements, thus satisfy a basic requirement of the STM. To stabilize the truss structures two methods were explored. (i) The addition of new members outside of the stress paths (stabilizers), the essential characteristic of these new elements is that the axial force in them should be zero to not change the stress distribution found during the optimization process. A sensitivity analysis of the stabilizers was performed to track how the axial force changes in these members depending on the position of the nodes connected to them, this process was necessary because when an element outside the stress paths has axial force the stress diagrams have been changed. (ii) The creation of substructures within the stress paths, this process stabilizes the global structure without the addition of members outside the stress paths. Finally, a structural analysis was performed to obtain the axial forces in each member of the truss structure, and through an analysis of these results, the total amount of tension forces in the truss was computed. The truss with the minimum value of total tension force is assumed as the most optimal structure for each case. It is clear through the analysis that the variation of the input parameters does not cause large variations in the results of the topology optimization, but it has an impact in the stabilization process and the performance of the structures according to the evaluation criterion. Furthermore, it has been proved that suitable trusses for the STM can be created using any of the two selected optimization approaches obtaining good results, and a similar performance according to the evaluation criterion.KStrutandTie model; Topology Optimization; Truss structures; Tension forceen
master thesisCivil Engineering)uuid:2afbfe96c9bf44d7bfaad8a710fa1ce2Dhttp://resolver.tudelft.nl/uuid:2afbfe96c9bf44d7bfaad8a710fa1ce2Topologically Optimised Cast Glass Grid Shell Nodes: Exploring Topology Optimisation as a design tool for Structu< ral Cast Glass elements with reduced annealing timeADamen, Wilfried (TU Delft Architecture and the Built Environment)Oikonomopoulou, Faidra (mentor); Turrin, Michela (mentor); Louw, Erik (graduation committee); Delft University of Technology (degree granting institution)Cast glass is a promising structural material that has seen increasing use in the build environment over the last year. It offers a great freedom of shape for designers and engineers, beyond the twodimensional float glass that is still primarily used. Despite this, cast glass in practice has only been used for solid bricks, mimicking traditional ceramic brickwork. Little exploration has been made on the complex shapes that can be achieved in cast glass. One of the largest challenges of cast glass is its slow and meticulous cooling process required after casting, to prevent the occurrence of internal stresses. This costly annealing process is the main limitations for producing large scale cast glass elements in an affordable way. Experience in large scale solid glass mirror castings performed for NASA show that annealing times can be reduced through smart design. <br/>Structural topology optimisation is a design tool for creating lightweight, material efficient elements. Its application has mostly been limited to industrial and aerospace design, though it is slowly being introduced in the built environment as the additive manufacturing required for these geometries becomes more advanced, and affordable. So far, topology optimisation of cast glass design has remained unexplored. The goal of this thesis is to investigate the potential of using topology optimisation as a design tool for complex structural castglass elements with a reduced annealing time. For this, a complexshaped grid shell has been redesigned in glass, using optimised cast glass nodes. The entire fabrication process, from digital design, to physical fabrication using additive manufacturing has been explored.cast glass; topology optimization; Topology Optimisation; Shell Structures; Generative Design; structural optimization; Glass structuresBArchitecture, Urbanism and Building Sciences  Building Technology)uuid:51dde3f62a3847a0b719420ff74ded5dDhttp://resolver.tudelft.nl/uuid:51dde3f62a3847a0b719420ff74ded5dZTopology optimization for highresolution designs: Application in solar cell metallization<Gupta, D.K. (TU Delft Structural Optimization and Mechanics)qvan Keulen, A. (promotor); Langelaar, M. (promotor); Delft University of Technology (degree granting institution)wDue to global population growth and industrial development, there is a rising demand for energy. It is desired that this demand is met in a cleaner and more sustainable way. Among the various renewable energy sources, solar power is experiencing remarkable growth throughout the world. To ensure that solar power can be a sustainable solution for the future energy demands, intensive research is being conducted to make solar cells more efficient and thereby reduce the cost of solar energy. Solar cells have metallization patterns on the front side to collect current generated in the semiconductor layer. The performance of a solar cell significantly depends on the amount of electrode material used for metallization, and the pattern in which it is deposited. There exist several optimization approaches to optimize the metallization distribution on the front surface of solar cells. However, due to the numerical simplifications associated with these methods, only limited gains in power output are observed. Moreover, the applicability of these methods is historically restricted to rectangular or circular domains. There has recently been a drive towards increased freeform photovoltaic installations. Given that these shapes can be very arbitrary, the optimal metallization patterns for such geometries can be expected to be complex, and the traditional methods cannot be used to design them.`metallization designs; solar cells; topology optimization; freeform; multiresolution; adaptivitydoctoral thesis9789463661522)uuid:2e2ec285< 300a4b9a8554c379fca1c63cDhttp://resolver.tudelft.nl/uuid:2e2ec285300a4b9a8554c379fca1c63cTopology optimization of coupled heat problems: An investigation of a combined thermomechanical and thermofluid topology optimization towards improving optical performance of a beamsteering mirrorHoogerbrugge, AryJan (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Precision and Microsystems Engineering)Langelaar, Matthijs (mentor); van Ostayen, Ron (mentor); van der Kolk, Max (mentor); Koevoets, Marco (mentor); Delft University of Technology (degree granting institution),In modern ASML machines optical components play an important role in the lithography process. EUV light is transported from the source to wafer by reflective optics. These mirrors are subjected to large thermal loading, as a large portion of the reflected light is absorbed in the mirror structure. The portion of the absorbed light is strongly dependent on the intensity and wavelength of the considered light, introducing varying amounts of thermally induced strains on the mirror structure and thereby limiting the optical performance. Current mirror designs typically use solid mirror structures for more predictable deformations. These structures are coupled to spiral cooling channels to extract the absorbed heat to achieve more uniform temperature distributions. However, as ASML strives towards ever smaller resolutions, advances have to be found on the mirror design methodology to further reduce the thermally induced strains. <br/>In this research, topology optimization is used as a possible method of producing designs which can minimise the thermally induced surface deformations of a mirror typically encountered when exposed to thermal loading. Due to the "multiphysics" nature of this problem, the optimization problem has to encompass thermomechanics, thermofluidics and the conjugate heat transfer at the interface of these two domains. The topology optimization formulation presented in this research, minimises surface deformations by altering the topology of the mirror structure together with the cooling channel layout producing an integrated solution.Topology Optimization; Thermomechanical; Thermofluid; Conjugate heat transfer; Convection; Cooling channels; Mirror; Optical performance; Adjoints; Gradientbased Optimization,Systems and Control  Mechanical Engineering)uuid:83241b6958184b4aa6902bedfc8d9b40Dhttp://resolver.tudelft.nl/uuid:83241b6958184b4aa6902bedfc8d9b40.Topology optimization for multiaxis machining>Langelaar, M. (TU Delft Structural Optimization and Mechanics)This paper presents a topology optimization approach that incorporates restrictions of multiaxis machining processes. A filter is defined in a densitybased topology optimization setting, that transforms an input design field into a geometry that can be manufactured through machining. The formulation is developed for 5axis processes, but also covers other multiaxis milling configurations, e.g. 2.5D milling and 4axis machining by including the appropriate machining directions. In addition to various tool orientations, also userspecified tool length and tool shape constraints can be incorporated in the filter. The approach is demonstrated on mechanical and thermal 2D and 3D numerical example problems. The proposed machining filter allows designers to systematically explore a considerably larger range of machinable freeform designs through topology optimization than previously possible.~2.5D milling; 5axis machining; Design for Manufacturing; Multiaxis milling; Subtractive manufacturing; Topology optimizationjournal articleEGreen Open Access added to TU Delft Institutional Repository You share, we take care! Taverne project https://www.openaccess.nl/en/yousharewetakecare Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.
20190927)uuid:c5ff51fecfe14d24b1407e136406f51aDhttp://resolver.tudelft.nl/uuid:c5ff51fecfe14d24b140< 7e136406f51ajHomogenizationbased stiffness optimization and projection of 2D coated structures with orthotropic infillGroen, J.P. (Technical University of Denmark); Wu, J. (TU Delft Materials and Manufacturing); Sigmund, Ole (Technical University of Denmark)This paper concerns compliance minimization and projection of coated structures with orthotropic infill material in 2D. The purpose of the work is twofold. First, we introduce an efficient homogenizationbased approach to perform topology optimization of coated structures with orthotropic infill material. The design space is relaxed to allow for a composite material description, which means that designs with complex microstructures can be obtained on relatively coarse meshes. Second, a method is presented to project the homogenizationbased designs on a fine but realizable scale. A novel method to adaptively refine the lattice structure is presented to allow for a regular spacing of the infill. Numerical experiments show excellent behavior of the projected designs, with structural performance almost identical to the homogenizationbased designs. Furthermore, a reduction in computational cost of at least an order of magnitude is achieved, compared to a related approach in which the infill is optimized using a densitybased approach.QCoated structures; Highresolution; Homogenization; Infill; Topology optimizationAccepted author manuscript
20210315)uuid:f51306b331164cc7bdaccd409df4e99fDhttp://resolver.tudelft.nl/uuid:f51306b331164cc7bdaccd409df4e99faIntegrated componentsupport topology optimization for additive manufacturing with postmachiningPurpose: The purpose of this paper is to communicate a method to perform simultaneous topology optimization of component and support structures considering typical metal additive manufacturing (AM) restrictions and postprint machining requirements. Design/methodology/approach: An integrated topology optimization is proposed using two density fields: one describing the design and another defining the support layout. Using a simplified AM process model, critical overhang angle restrictions are imposed on the design. Through additional load cases and constraints, sufficient stiffness against subtractive machining loads is enforced. In addition, a way to handle nondesign regions in an AM setting is introduced. Findings: The proposed approach is found to be effective in producing printable optimized geometries with adequate stiffness against machining loads. It is shown that postmachining requirements can affect optimal support structure layout. Research limitations/implications: This study uses a simplified AM process model based on geometrical characteristics. A challenge remains to integrate more detailed physical AM process models to have direct control of stress, distortion and overheating. Practical implications: The presented method can accelerate and enhance the design of high performance parts for AM. The consideration of postprint aspects is expected to reduce the need for design adjustments after optimization. Originality/value: The developed method is the first to combine AM printability and machining loads in a single topology optimization process. The formulation is general and can be applied to a wide range of performance and manufacturability requirements.Additive manufacturing; Design; Design for manufacturing; Optimization; Overhang; Postmachining; Rapid manufacturing; Subtractive machining; Support structures; Topology optimization)uuid:80ae1398bb2c4f96a0ec282d849349c5Dhttp://resolver.tudelft.nl/uuid:80ae1398bb2c4f96a0ec282d849349c5DCompliant Fluidic Control Structures: Concept and synthesis approachKumar, P. (TU Delft Structural Optimization and Mechanics); Fanzio, P. (TU Delft Micro and Nano Engineering); Sasso, L. (TU Delft Micro and Nano Engineering); Langelaar, M. (TU Delft Structural Optimization and Mechanics)The concept and synthesis approach for planar Compliant Fluidic Control Structures (CFCSs), monolithic flexible continua with embedded functional pores, is presented in this man< uscript. Such structures are envisioned to find application in biomedicine as tunable microfluidic devices for drug/nutrient delivery. The functional pores enlarge and/or contract upon deformation of the compliant structure in response to external stimuli, facilitating the regulated control of fluid/nutrient/drug transport. A thickness design variable based topology optimization problem is formulated to generate effective designs of these structures. An objective based on hydraulic diameter(s) is conceptualized, and it is extremized using a gradient based optimizer. Both geometrical and material nonlinearities are considered. The nonlinear behaviour of employed hyperelastic material is modeled via the ArrudaBoyce constitutive material model. Largedisplacement finite element analysis is performed using the updated Lagrangian formulation in planestress setting. The proposed synthesis approach is applied to various CFCSs for a variety of fluidic control functionalities. The optimized designs of various CFCSs with single and/or multiple functional pores are fabricated via a Polydimethylsiloxane (PDMS) soft lithography process, using a high precision 3D printed mold and their performances are compared with the numerical predictions.jCompliant structures; Microfluidic devices; Nonlinear finite element analysis; PDMS; Topology optimization
20190904)uuid:6fa5e07edd524aa2abe0ca9c238d5117Dhttp://resolver.tudelft.nl/uuid:6fa5e07edd524aa2abe0ca9c238d5117kSimultaneous optimization of shape and topology of freeform shells based on uniform parameterization modelXia, Y. (TU Delft Applied Mechanics; Harbin Institute of Technology); Wu, Yue (Harbin Institute of Technology); Hendriks, M.A.N. (TU Delft Applied Mechanics; Norwegian University of Science and Technology (NTNU))In current optimization methods for freeform shells, the shape and topology are usually optimized separately. These methods are based on the assumption that the shape and topology of a shell influence each other only slightly, but this is not always correct. Moreover, different parameterization models are used in the shape optimization and topology optimization of freeform shells, which brings difficulties to carry out the integrated optimization. To solve this problem, an integrated method is proposed for simultaneously optimizing shape and topology for freeform shells. A uniform parameterization model based on NURBS solids is established to parameterize the freeform shells. In this model, only a small number of variables are used to describe both the shape and topology of the shell. In this way, the integrated optimization problem can be simplified, thus decrease the computational complexity. The integrated optimization of shape and topology is a complicated and largescale optimization problem. Solving this problem requires a suitable optimization method. In this paper, the Method of Moving Asymptotes (MMA) is adopted. Finally, numerical examples are presented to address the importance of the optimization sequences and show the effectiveness and application of the proposed method.zFreeform shell; Integrated optimization; NURBS; Shape optimization; Topology optimization; Uniform parameterization modelAccepted Author Manuscript
20210301)uuid:ab92c1fba5b14302b2b4fcd36b84f0dcDhttp://resolver.tudelft.nl/uuid:ab92c1fba5b14302b2b4fcd36b84f0dcHStructural topology optimization of an active motion compensated gangwaytVergeer, Michael (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Marine and Transport Technology)Miedema, Sape (graduation committee); Langelaar, Matthijs (graduation committee); Helmons, Rudy (graduation committee); Kromwijk, PJ (mentor); Delft University of Technology (degree granting institution)uIn the offshore industry, there is a growing demand for designing efficient, sustainable and competitive products. In order to fulfil the component requirements, a method named topology optimization can be applied. This is a mathematical design method which can be used in the early phases of the design process.At IHC there is< an interest of applying topology optimization for their equipment development process. Therefore the possibilities and limitations of the method should be investigated thoroughly.<br/><br/>The research covers the optimization process of a motion compensated gangway. A motion compensated gangway is a walkway which can be used to provide access from the transport vessel to the offshore structure. Its function is to transport people and cargo safely from the ship to the offshore structure or vice<br/>versa. The goal of this research was to determine to what extent topology optimization can be used in the design of a motion compensated gangway. Finding an optimized result in terms of weight and stiffness by using this mathematical method which satisfies all the requirements. The structural optimization is carried out with several commercial software packages which are compared by using a multicriteria analysis.<br/><br/>During the optimization process it has been found that there are essentially two stages in the optimization process. In the first stage, the topology or beam orientation of the structure is defined by the topology optimization process. In this part the concept of the design is generated. Variation of the optimization parameters was used in order to develop an efficient structure. The objective for the optimizer was to minimize the compliance of the structure for a certain volume fraction.<br/><br/>In the second stage, the dimensions of all the beams and elements are defined by performing a size optimization. A line model is generated which represents the orientation of the members in the structure. During the size optimization the shape and the dimensions of the members are defined in order to fulfill the<br/>objective. The objective is to minimize the mass of the structure while constraints are defined for the maximum allowable stresses in the members and the maximum vertical deflection of the structure. This postprocessing step is required in order to obtain a feasible design. The structural stability of the gangway was improved by performing a linear buckling analysis and by adapting the structure in order to reduce the buckling behaviour.<br/><br/>In the final step of the optimization process, a CAD drawing is generated. This model is analysed by performing a finite element analysis. This showed that the new optimized design satisfies all the requirements which are stated by the DNV for designing a motion compensated gangway. The combination of the topology and size optimization resulted in a new design which yielded a weight reduction of 36,4% compared to the current design. The weight was reduced from 13,08 ton to 8,31 ton, while still satisfying all the constraints. Therefore it can be concluded that this methodology can be used in the optimization of a motion compensated gangway structureOptimization; Topology optimization; Shape optimization; Motion compensated gangway; Structural Optimization; Optistruct; Hyperworks; Size optimization; Design methodology
20201009!Offshore and Dredging Engineering)uuid:7d9397626ad247769fb7a8b0a31f876fDhttp://resolver.tudelft.nl/uuid:7d9397626ad247769fb7a8b0a31f876ftCompatibility in microstructural topology optimization: A physical method for generating connectable microstructures5Garner, Eric (TU Delft Industrial Design Engineering)fWu, Jun (mentor); Zadpoor, Amir (mentor); Delft University of Technology (degree granting institution)Microstructural materials with spatiallyvarying properties, such as trabecular bone tissue, are widely seen in nature. These functionally graded structures possess smoothly changing microscale topologies that enable performance far superior to that of their base material. While the optimization of periodic microstructures has been studied in depth, less attention has been paid to the assembly of optimized microstructures with spatially varying properties. Existing works address this problem by ensuring geometric connectivity between adjacent microstructural unit cells. In this report, we argue that geometric connectivity is insuffici< ent to ensure the continuation of physical properties, and propose the concept of mechanical compatibility. Mechanical compatibility directly examines the effective mechanical properties of the individual cell together with its neighbour. Our approach simultaneously optimizes the mechanical properties of individual microstructures as well as those of neighbouring pairs, so that material connectivity and smoothly varying physical properties are ensured. We demonstrate the application of our method in the design of functionally graded material for implant design, and in the design of both coupled and decoupled multiscale structures.Imaterial design; metamaterials; topology optimization; advanced materials
20190817Integrated Product Design)uuid:827d2a24b449408f91210d371f8173ccDhttp://resolver.tudelft.nl/uuid:827d2a24b449408f91210d371f8173cc5Topology optimization of constrained eigenfrequenciesJHuigsloot, Menno (TU Delft Mechanical, Maritime and Materials Engineering)Langelaar, Matthijs (mentor); Keyvani Janbahan, Sasan (mentor); Delft University of Technology (degree granting institution)
High performance machines such as those used in the semiconductor industry, robotics or racing engines have lots of fast moving parts. The dynamic properties of these moving parts are crucial to the performance of the machine. Therefore these moving parts have to be carefully designed which is often a very time consuming iterative process. In this thesis a general method to optimize the dynamic properties of a structure utilizing topology optimization is investigated. More specifically, the method will be focused on the optimization of eigenfrequencies whilst achieving specific ratios between eigenfrequencies,<br/>as dynamic performance requirements are often linked to such criteria. We refer to this class of topology optimization problems as problems involving constrained eigenfrequencies. A particular case of interest is the desired multiplicity of two or more eigenfrequencies, that is a ratio of 1. <br/><br/>Several crucial aspects of the topology optimization of eigenfrequencies are investigated, these are the material interpolation methods, mode tracking techniques, multiplicity problems and obtaining a discrete design. By comparing different material interpolation methods, a clear view on the effects of different methods is obtained, leading to solid arguments for selecting a linear material interpolation method for topology optimization of eigenfrequencies. A simple yet effective method of tracking the<br/>eigenmodes during the optimization process combined with a solution for the multiplicity problems is presented and verified to show similar results as a more complex analytical approach. A new method of obtaining a discrete design without applying penalization or modification of the eigenvalue problem<br/>has been developed using a modified objective function. This method shows promising results and is a good candidate for replacing the material interpolation penalization method. By combining these results, a general and capable framework for the topology optimization of constrained eigenfrequencies is obtained. Using the presented framework, a practical application of the method is given by the design of a cantilever used in an atomic force microscope. Feasible and wellperforming designs have been generated, both from a functional and manufacturing point of view.5Topology optimization; Eigenfrequencies; multiplicity+Structural Optimization and Mechanics (SOM))uuid:b121092a4b024ec18888c2cbe893094dDhttp://resolver.tudelft.nl/uuid:b121092a4b024ec18888c2cbe893094d<Topology optimization involving constrained eigenfrequenciesLangelaar, Matthijs (mentor); Keyvani Janbahan, Sasan (graduation committee); Delissen, Arnoud (graduation committee); Delft University of Technology (degree granting institution)High performance machines such as those used in the semiconductor industry, robotics or racing engines have lots of fast moving parts. The dynamic properties of these moving parts are crucial to the performance of the machi< ne. Therefore these moving parts have to be carefully designed which is often a very time consuming iterative process. In this thesis a general method to optimize the dynamic properties of a structure utilizing topology optimization is investigated. More specifically, the method will be focused on the optimization of eigenfrequencies whilst achieving specific ratios between eigenfrequencies,<br/>as dynamic performance requirements are often linked to such criteria. We refer to this class of topology optimization problems as problems involving constrained eigenfrequencies. A particular case of interest is the desired multiplicity of two or more eigenfrequencies, that is a ratio of 1. Several crucial aspects of the topology optimization of eigenfrequencies are investigated, these are the material interpolation methods, mode tracking techniques, multiplicity problems and obtaining a discrete design. By comparing different material interpolation methods, a clear view on the effects of different methods is obtained, leading to solid arguments for selecting a linear material interpolation method for topology optimization of eigenfrequencies. A simple yet effective method of tracking the eigenmodes during the optimization process combined with a solution for the multiplicity problems is presented and verified to show similar results as a more complex analytical approach. A new method of obtaining a discrete design without applying penalization or modification of the eigenvalue problem has been developed using a modified objective function. This method shows promising results and is a good candidate for replacing the material interpolation penalization method. By combining these results, a general and capable framework for the topology optimization of constrained eigenfrequencies is obtained. Using the presented framework, a practical application of the method is given by the design of a cantilever used in an atomic force microscope. Feasible and wellperforming designs have been generated, both from a functional and manufacturing point of view.Topology optimization; eigenfrequencies; multiplicity; material interpolation; mode tracking; discrete designs; black and white design; AFM; cantilever)uuid:83784e45abe64800b86242d7dba09c75Dhttp://resolver.tudelft.nl/uuid:83784e45abe64800b86242d7dba09c75]Topology Optimization of Wave Barriers: Development of a tool for use in engineering practice[de Zeeuw, Alwin (TU Delft Civil Engineering and Geosciences; TU Delft Structural Mechanics)Metrikine, Andrei (mentor); van Dalen, Karel (mentor); Steenbergen, Michael (mentor); Stuit, Herke (mentor); Delft University of Technology (degree granting institution)Wave barriers are a common mitigation measure when dealing with environmentally induced vibrations. These wave barriers generally consist of stiff vertical walls buried in the soil to impede waves on their path from the source to the receiver. The geometries of the wave barriers that are used in practice are very simple. More complex geometries have not often been considered as it is difficult to estimate which changes would increase the effectiveness.<br/><br/>In literature, topology optimization was explored as a method to design wave barriers. This method was applied while modelling the soil as a homogeneous elastic halfspace. The resulting wave barriers showed a significant increase in the achieved vibration reduction. However, the designs were often very complex and hard to manufacture. In this thesis the method was improved by introducing a layered soil and by ensuring the manufacturability of the designed wave barriers.<br/><br/>The improved method was then applied to multiple situations in order to investigate aspects of wave barrier design and effectiveness. Optimization of a wave barrier for a twolayered soil model showed the significance of implementing a layered soil model. The interface between two layers resulted in reflections that could diminish the effectiveness of a wave barrier if not accounted for. The optimization algorithm responded to these reflections by placing mate< rial in the path of waves that would otherwise reflect back to the surface.<br/><br/> A wave barrier optimized for a threelayered soil model that consisted of a softer layer embedded in a stiff layer and a stiff halfspace showed a different approach to reflections. The wave barrier appeared to use the softer layer as a waveguide in order to reduce the energy at the surface.<br/><br/>The manufacturability was increased by adding constraints. This resulted in wave barriers with a more manufacturable design at the cost of a decrease in vibration reduction. In three of the four cases, the optimized wave barrier still performed significantly better than the reference wave barrier. In one case, the final design reverted back to the reference wave barrier when the manufacturability conditions were applied.<br/><br/>The goals set at the start of the thesis were largely accomplished. The model was able to more accurately reflect soil profiles found in practice by using a layered soil model and the topology optimization algorithm resulted in wave barriers that are relatively easy to manufacture while still showing a significant improvement over the standard reference wave barriers. The possible use of<br/>soft embedded layers as waveguides was discovered during the optimization. Future research into this possibility could prove valuable. Some concerns are posited with regards to the reliability of the wave barriers. In some cases, the optimized wave barrier appeared to abuse the idealized representation of the interface between layers. An initial investigation showed that in those cases,<br/>the effectiveness of the wave barrier was sensitive to changes of the interface depth. Further investigation would be required to determine the sensitivity of the designed wave barriers to other parameters related to the idealized representations of the interfaces.<brUTopology Optimization; Wave Barriers; Railwayinduced vibration; frequency domain; 2D)uuid:efd1ad24017f48ac8e31184339a9d148Dhttp://resolver.tudelft.nl/uuid:efd1ad24017f48ac8e31184339a9d148UApplication of Evolutionary Structural Optimization to Reinforced Concrete StructuresqDe Marco, Andrea (TU Delft Civil Engineering and Geosciences; TU Delft Materials Mechanics Management & Design)Hendriks, Max (mentor); Rots, Jan (graduation committee); Braam, Rene (graduation committee); Langelaar, Matthijs (graduation committee); Delft University of Technology (degree granting institution)
The present thesis has the objective to create a procedure for the automatic preliminary design of reinforced concrete structures, based on the Evolutionary Structural Optimization method (ESO). The developed algorithm performs heuristic topology optimization based on multiple criteria, in subsequent optimization cycles executed in series. In each ESO cycle, it is possible to perform material addition, removal or transition between a couple of materials, i.e. steel, concrete and void. Each optimization cycle is governed by an optimality criterion chosen from: stiffness, Von Mises, DruckerPrager, tension stress criteria or linear interpolation of previous ones. The finite element analysis used in the algorithm regards all materials as linear elastic. The reaching of maximum strength and failure of materials is not taken into account.<br/><br/>The automated design process of reinforced concrete structures has been separated in two problems: the formfinding of reinforced concrete structure as a whole and the definition of internal distribution between steel and concrete. The first problem is solved, in the first optimization cycle, with a ``standard'' ESO procedure, with the only difference in choosing a Von Mises optimization criterion over a ``classical'' stiffness criterion. The second problem is solved, in the second and third optimization cycles, combining in series two additional ``modified'' ESO procedures and introducing gradual transition in optimization criteria through linear interpolation of sensitivity numbers. The combined criteria for the second cycle are a Von Mises and DruckerPrager optim< ization criteria, while for the third cycle, a DruckerPrager and tensile stress optimization criteria. Moreover, additional geometrical constraints are applied, to ensure a set minimal distance between steel and outer boundaries, i.e. concrete cover, and to ensure optimal angle preservation for steel members found during optimization, introducing two new ``density'' matrices called \emph{cover} and \emph{mask}.<br/>Summarizing, the preliminary design of reinforced concrete structures is dealt with three cycles of ESO optimization procedures executed in series, with optimization criteria that gradually change with continuity between the different cycles over the whole process.<br/><br/>The developed procedure has been tested on several case studies, both from ESO and reinforced concrete literature. The defined ESO process has been found to generate solutions with steel correctly placed in tensile stress zones both to resist bending and shear. Generally, the presence of remaining tensile stresses in concrete zones in the solutions is absent or very limited, and in latter cases their magnitude is very small compared to other stresses.<br/>Obtained solutions cannot be directly used as such for reinforcement layouts definition but, in combination with principal stresses plots and engineering judgement, they are able to suggest useful resulting reinforcement layouts.<br/><br/>As result of the specificities introduced for addressing the design of reinforced concrete structures, the ESO method has been extended for the case of topological optimization of composite materials with macro structure, with different optimization criteria applied to component materials, with one component material that has different resistance in tension and compression and with geometrical constraints for one component material.<br/><br/>The complete MATLAB code is published in the annex.IEvolutionary Structural Optimization; Bidirectional Evolutionary Structural Optimization; Computational Optimization; Topology Optimization; Structural Optimization; Heuristic Optimization; ESO; BESO; Optimization Algorithm; Optimization Procedure; Reinforced Concrete Structures; Reinforced Concrete Design; Reinforced Concrete)uuid:cabd406bf4a8473392b880934a272780Dhttp://resolver.tudelft.nl/uuid:cabd406bf4a8473392b880934a272780`On the Assessment of the Potential of Topology Optimization: in the Maritime Construction SectorSanchezSimon del Pino, Claudia (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Marine and Transport Technology)Pruijn, Jeroen (mentor); Hopman, Hans (graduation committee); Walters, Carey (graduation committee); Delft University of Technology (degree granting institution)Topology Optimization is an optimization problem based on the distribution of material within a design domain under specific load states. The goal of this technology is minimizing a certain function, such as compliance, mass or frequency. <br/>This technology can improve the performance of components in different fields within the shipbuilding industry, depending on the function of the element and which type of ship they belong to. The three areas of application in which this technology was thought to have a big impact were weight reduction, aesthetics and comfort.<br/>It is a common thought that Topology Optimization could only help to the diminution of mass of bodies. Nonetheless, this reduction of weight does not benefit to all the ships. Cargo ships with a cargo limitation due to volume are less likely to take an advantage of its lightweight cutback than those with a cargo capacity limitation by weight. Moreover, vessels with a very low center of gravity would suffer stability disorders, such as cruise ships. <br/>The area of aesthetics was studied from a different point of view: now the construction industry was not perceived as only dedicated to maintain the integrity of structures, but an artistic point of view was explored with the target of resembling the ideas of consumers and transmitting feelings to customers. Vessels with a greater interest in the a< ppearance are the ones dedicated to the transport of passengers, such as ferries and cruise ships and also those ships with a focus on the luxurious face of the marine construction sector, such as yachts. <br/>In the search of improvements regarding comfort, the focus was kept on the vibration phenomenon and the occurrence of noise. Vibrations are harmful for machinery, crew, passengers and the overall structure of the craft and therefore is an issue to be avoided as much as possible. With this target, Topology Optimization was applied on a mast under certain circumstances, taking into account the amount and allocation of navigation devices these elements must carry. <br/>This thesis aims to give an introduction to what can be achieved with the technology of Topology Optimization in the maritime sector. Although no decisive results were achieved for some of the previously presented elements, findings were attained and the potential of this application is positive. Nevertheless, more research is required in order to build solid confirmations about the profitability of the implementation of Topology Optimization. Moreover, manufacturing processes, and more specifically Additive Manufacturing is to be grown in order to fulfill the structural requirements of the optimal components. This refers not only to the fabrication process itself, but also to the implementation of this methodology in Regulations by Classification Societies. <brWTopology Optimization; Vibrations; Aesthetics; Weight Reduction; Additive Manufacturing
20230419&Ship Design, Production and Operations)uuid:bc7fe427d9344ea595366a7d14ad1f59Dhttp://resolver.tudelft.nl/uuid:bc7fe427d9344ea595366a7d14ad1f59Comparative Assessment of Possible Topologies of Offshore Transmission Network in the North Sea: Role of the North Sea Wind Power Hub at the Dogger BankQChen, Qinghan (TU Delft Electrical Engineering, Mathematics and Computer Science)van der Meijden, Mart (mentor); Rueda Torres, Jose (mentor); Lahaye, Domenico (graduation committee); Delft University of Technology (degree granting institution)1TenneT s vision of the North Sea Infrastructure (NSI) creates a basis for a joint European approach up to 2050 which focuses specifically on developing the North Sea as a source and distribution hub for Europe s energy transition. High wind speed, central location and shallow water qualify the Dogger Bank as the location of the central hub.<br/>For further development of the NSI, more detailed research is needed.<br/>The research gap is recognized that there is not sufficient research on proposing new HVDC grids in the North Sea considering optimization (e.g. following a costrelated objective) of different topology structures within a scope of six surrounding countries (BE, DE, DK, GB, NL and NO), with sensitivity tests regarding uncertainties (e.g. in meteorological condition, load, or industry development).<br/>Therefore, the main research objective of this thesis project is to evaluate CAPEX, overall OPEX of participating countries and other operational performances (e.g. energy mix, nodal price, EENS) of possible topologies of HVDC network in the North Sea, including NSI (with a central North Sea Wind Power Hub at the Dogger Bank) and other two competitive topologies, considering uncertainties in green energy technology development, European coordination, load and meteorological condition (e.g. wind speed, solar radiation and hydrology).<br/>Three specific research questions were studied in order to achieve the aforementioned research objective: How to define 3 topologies of the North Sea HVDC network with different feasible structures? What are the criteria to optimize each topology and to compare the topologies? What are the implications of each topology, when evaluated against a wide range of uncertainties, on the overall CAPEX and OPEX of countries involved?<br/>The simulation considers the scenario in the year 2030. Software PowerGAMA and PowerGIM were used for operation simulation and topology optimization. When calculating OPEX throughout the lifetime of the e< quipment (assuming 30 years), the year 2030 is taken as a representative year and the 30year OPEX is obtained by multiplying OPEX in 2030 by an annuity factor.<br/>In short, 3 topologies of the North Sea HVDC grid, with hubandspoke structure (for the NSI), pointtopoint structure and meshed (without central energy hub) structure, respectively, are defined. They are then optimized towards and compared for the lowest overall cost (i.e. the sum of CAPEX and OPEX including CO2 prices) throughout the lifetime.<br/>Simulating under different uncertainties/selected critical scenarios (4 Visions from ENTSOE s Ten Year Network Development Plan which reflect different RES share target and European coordination level, and extreme RES inflow and load conditions), the optimized NSI design stays most socioeconomically preferable (with lowest overall cost) topology.<br/>It is also recognized that NSI is able to realize its expected functions, namely transmission of renewable energy, enhancement of system security and price convergence. On the other hand, launching of NSI brings in challenges such as grid congestion and benefit asymmetry.<br/>Main contributions of this thesis include:<br/>" Creation of the baseline model/dataset for European power system in 2030 as a background/environment for the North Sea HVDC grid planning;<br/>" Design and optimization of the North Sea HVDC grid topologies in three different feasible structures;<br/>" Verification of NSI s advantage in cost saving, compared to two competitors, in 4 Visions reflecting different green energy transition and European coordination level, and under extreme RES inflow and load conditions;<br/>" Verification of NSI s function in improving energy sustainability, affordability and security;<br/>" Realization of NonHomogeneous Markov Chain algorithm in Excel to generate wind power inflow time series.uNorth Sea Infrastructure; North Sea Wind Power Hub; offshore HVDC grid; topology optimization; comparative assessmentElectrical Engineering)uuid:9677fc1d8d994977b7e34708ee7d22afDhttp://resolver.tudelft.nl/uuid:9677fc1d8d994977b7e34708ee7d22afiAdditively manufactured suspension components for an F1 car: Design, Simulation,Manufacturing and TestingKZamariola, Nicolo (TU Delft Mechanical, Maritime and Materials Engineering)TSietsma, Jilt (mentor); Delft University of Technology (degree granting institution))The recent possibilities given by additive manufacturing in free shape design have been seen as a<br/>potential breakthrough in the design and production of structural components of a racecar and more<br/>generally their influences on the future lightweight strategies in the automotive industry is expected<br/>to influence the next generation of products. Among the emerging techniques for the production of<br/>metal products, Direct Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM) technologies<br/>are becoming technically ahead of the competition: the possibility of direct production of aluminum<br/>and titanium alloys components with good surface finishing and net shape from CAD geometry is<br/>nowadays a concrete option for the mechanical designer.<br/>The purpose of the present study is to demonstrate the feasibility of thementionedAMtechniques<br/>and to exploit their potentialweight saving opportunities in the design of highly structurally optimized<br/>racing components while determining the current stateofart of AM for metallic components. The<br/>present project reports the design and production of two car components redesigned in the perspective<br/>of the novel manufacturing techniques.<br/>The first component is the rear top wishbone bracket of the rear suspension. The production<br/>has been developed following the best practices for the design of additively manufactured structures<br/>such as complete topology optimization and a reconstruction with special focus on the design for<br/>manufacturing assessment. The bracket has been developed for DMLS manufacturing in titanium<br/>alloy Ti6Al4V. On the contrary, the second component has been develope< d in a novel aluminumalloy:<br/>the Scalmalloy, commercial name of a high strength aluminum alloy specifically developed for high<br/>strength to weight critical applications. For this novel material a characterization campaign has been<br/>set up comprehending tensile testing, micrographical analysis, tomography inspection and an Xray<br/>analysis. Both component underwent a full scale fatigue testing.<br/>Both components proved an achievement in terms of weight saving between 7% and 10%with the<br/>same functionality and performance level of the machine counterparts. The material characterization<br/>campaign revealed the concrete maturity of the DMLS process for Ti6Al4V while the process of SLM<br/>production of Scalmalloy requires some final tuning. The tensile strength levels achieved are compliant<br/>for both materials specifications but the presence of localized lack of fusion in the Scalmalloy<br/>specimens reduced the final ductility of the material considerably.<br/>The obtained results are an encouraging step towards the application of the analyzed technology<br/>in structural components for the motorsport industry and possibly, in the near future, for the wider<br/>automotive industry. The limited standardization in the quality processes is addressed as well with<br/>a concrete proposal for establishing a controlled level of defects in additively manufactured components.RScalmalloy; Additive Manufacturing; Selective Laser Melting; Topology optimization
20230112?Mechanical Engineering  Materials Engineering and Applications44.53111, 10.86278)uuid:3e9873dda6d649d68fc557c0ab99acaeDhttp://resolver.tudelft.nl/uuid:3e9873dda6d649d68fc557c0ab99acaeMCurrent and future trends in topology optimization for additive manufacturingLiu, Jikai (University of Pittsburgh); Gaynor, Andrew T. (U.S. Army Research Laboratory); Chen, Shikui (State University of New York); Kang, Zhan (Dalian University of Technology); Suresh, Krishnan (University of WisconsinMadison); Takezawa, Akihiro (Hiroshima University); Li, Lei (University of Notre Dame); Kato, Junji (Tohoku University); Tang, Jinyuan (Central South University); Wang, C.C. (TU Delft Materials and Manufacturing); Cheng, Lin (University of Pittsburgh); Liang, Xuan (University of Pittsburgh); To, Albert. C. (University of Pittsburgh)=Manufacturingoriented topology optimization has been extensively studied the past two decades, in particular for the conventional manufacturing methods, for example, machining and injection molding or casting. Both design and manufacturing engineers have benefited from these efforts because of the closetooptimal and friendlytomanufacture design solutions. Recently, additive manufacturing (AM) has received significant attention from both academia and industry. AM is characterized by producing geometrically complex components layerbylayer, and greatly reduces the geometric complexity restrictions imposed on topology optimization by conventional manufacturing. In other words, AM can make nearfull use of the freeform structural evolution of topology optimization. Even so, new rules and restrictions emerge due to the diverse and intricate AM processes, which should be carefully addressed when developing the AMspecific topology optimization algorithms. Therefore, the motivation of this perspective paper is to summarize the stateofart topology optimization methods for a variety of AM topics. At the same time, this paper also expresses the authors perspectives on the challenges and opportunities in these topics. The hope is to inspire both researchers and engineers to meet these challenges with innovative solutions.Additive manufacturing; Lattice infill; Material feature; Multimaterial; Posttreatment; Support structure; Topology optimization; Uncertainty
20190630Materials and Manufacturing)uuid:7d7e86d0c577434a870663db512a5726Dhttp://resolver.tudelft.nl/uuid:7d7e86d0c577434a870663db512a5726_Topology optimization of multicomponent optomechanical systems for improved optical performanceKoppen, S. (TU Delft Structural Optim< ization and Mechanics); van der Kolk, M. (TU Delft Structural Optimization and Mechanics); van Kempen, F.C.M. (TNO); de Vreugd, J (TNO); Langelaar, M. (TU Delft Structural Optimization and Mechanics)The stringent and conflicting requirements imposed on optomechanical instruments and the everincreasing need for higher resolution and quality imagery demands a tightly integrated system design approach. Our aim is to drive the thermomechanical design of multiple components through the optical performance of the complete system. To this end, we propose a new method combining structuralthermaloptical performance analysis and topology optimization while taking into account both component and system level constraints. A 2D twomirror example demonstrates that the proposed approach is able to improve the system s spot size error by 95% compared to uncoupled system optimization while satisfying equivalent constraints.Multidisciplinary design optimization; Optical instrumentation; Optomechanics; Structuralthermalopticalperformance analysis; System optimization; Thermoelasticity; Topology optimization%Structural Optimization and Mechanics)uuid:a36fed171aba4c758f27877de94ccad2Dhttp://resolver.tudelft.nl/uuid:a36fed171aba4c758f27877de94ccad2?QRpatterns: artefacts in multiresolution topology optimizationGupta, D.K. (TU Delft Structural Optimization and Mechanics); Langelaar, M. (TU Delft Structural Optimization and Mechanics); van Keulen, A. (TU Delft Structural Optimization and Mechanics)Recent multiresolution topology optimization (MTO) approaches involve dividing finite elements into several density cells (voxels), thereby allowing a finer design description compared to a traditional FEmeshbased design field. However, such formulations can generate discontinuous intraelement material distributions resembling QRpatterns. The stiffness of these disconnected features is highly overestimated, depending on the polynomial order of the employed FE shape functions. Although this phenomenon has been observed before, to be able to use MTO at its full potential, it is important that the occurrence of QRpatterns is understood. This paper investigates the formation and properties of these QRpatterns, and provides the groundwork for the definition of effective countermeasures. We study in detail the fact that the continuous shape functions used in MTO are incapable of modeling the discontinuous displacement fields needed to describe the separation of disconnected material patches within elements. Stiffness overestimation reduces with prefinement, but this also increases the computational cost. We also study the influence of filtering on the formation of QRpatterns and present a lowcost method to determine a minimum filter radius to avoid these artefacts.aArtefacts; Artificial stiffness; Multiresolution topology optimization; prefinement; QRpatterns)uuid:4af3727907114cb4b53a5340b6ec37a4Dhttp://resolver.tudelft.nl/uuid:4af3727907114cb4b53a5340b6ec37a4iContinuous front propagationbased overhang control for topology optimization with additive manufacturingTvan de Ven, E.A. (TU Delft Structural Optimization and Mechanics; NLR  Netherlands Aerospace Centre); Maas, Robert (NLR  Netherlands Aerospace Centre); Ayas, C. (TU Delft Structural Optimization and Mechanics); Langelaar, M. (TU Delft Structural Optimization and Mechanics); van Keulen, A. (TU Delft Structural Optimization and Mechanics)Additive manufacturing enables the nearly uncompromised production of optimized topologies. However, due to the overhang limitation, some designs require a large number of supporting structures to enable manufacturing. Because these supports are costly to build and difficult to remove, it is desirable to find alternative designs that do not require support. In this work, a filter is presented that suppresses nonmanufacturable regions within the topology optimization loop, resulting in designs that can be manufactured without the need for supports. The filter is based on front propagation, can be evaluated efficiently, and adjoint se< nsitivities are calculated with almost no additional computational cost. The filter can be applied also to unstructured meshes and the permissible degree of overhang can be freely chosen. The method is demonstrated on several compliance minimization problems in which its computational efficiency and flexibility are shown. The current applications are in 2D, and the proposed method is readily extensible to 3D.JAdditive manufacturing; Front propagation; Overhang; Topology optimization)uuid:a7b1277f72f14069a300915a82d14281Dhttp://resolver.tudelft.nl/uuid:a7b1277f72f14069a300915a82d142816CPV solar cell modeling and metallization optimizationGupta, D.K. (TU Delft Structural Optimization and Mechanics); Barink, Marco (TNO, Eindhoven); Langelaar, M. (TU Delft Structural Optimization and Mechanics)Concentrated photovoltaics (CPV) has recently gained popularity due to its ability to deliver significantly more power at relatively lower absorber material costs. In CPVs, lenses and mirrors are used to concentrate illumination over a small solar cell, thereby increasing the incident light by several folds. This leads to nonuniform illumination and temperature distribution on the front side of the cell, which reduces performance. A way to limit this reduction is to optimize the metallization design of the solar cell for certain nonuniform illumination and temperature profiles. Most of the existing metallization optimization methods are restricted to the conventional Hpattern, which limits the achievable improvements. Topology optimization alleviates such restrictions and is capable of generating complex metallization patterns, which cannot be captured by the traditional optimization methods. In this paper, the application of topology optimization is explored for concentrated illumination conditions. A finite element model that includes all relevant resistances combined with topology optimization method is presented and the applicability is demonstrated on nonuniform illumination and temperature profiles. The finite element model allows accurate modeling of the current density and voltage distributions. Metallization designs obtained by topology optimization significantly improve the power output of concentrating solar cells.Concentrated photovoltaics; Concentrating solar cells; Finite element model; Illumination; Metallization; Nonuniform; Optimal design; Temperature profile; Topology optimization
20180529)uuid:957510d2597149b7a7d678e3823e9bf4Dhttp://resolver.tudelft.nl/uuid:957510d2597149b7a7d678e3823e9bf4qCombined optimization of part topology, support structure layout and build orientation for additive manufacturingAdditive manufacturing (AM) enables the fabrication of parts of unprecedented complexity. Dedicated topology optimization approaches, that account for specific AM restrictions, are instrumental in fully exploiting this capability. In popular powderbedbased AM processes, the critical overhang angle of downward facing surfaces limits printability of parts. This can be addressed by changing build orientation, part adaptation, or addition of sacrificial support structures. Thus far, each of these measures have been studied separately and applied sequentially, which leads to suboptimal solutions or excessive computation cost. This paper presents and studies, based on 2D test problems, an approach enabling simultaneous optimization of part geometry, support layout and build orientation. This allows designers to find a rational tradeoff between manufacturing cost and part performance. The relative computational cost of the approach is modest, and in numerical tests it consistently obtains high quality solutions.Additive manufacturing; Build orientation; Design for manufacturing; Overhang angle; Printing direction; Support structures; Topology optimization)uuid:d2688b6cb8c2491b8993e00627fafa78Dhttp://resolver.tudelft.nl/uuid:d2688b6cb8c2491b8993e00627fafa78PTopology optimization with overhang filter considering accessibility of supportsTvan de Ven, E.A. (TU Delft Structural Optimization and Mechani< cs; NLR  Netherlands Aerospace Centre); Langelaar, M. (TU Delft Structural Optimization and Mechanics); Ayas, C. (TU Delft Structural Optimization and Mechanics); Maas, Robert (NLR  Netherlands Aerospace Centre); van Keulen, A. (TU Delft Structural Optimization and Mechanics)HTopology Optimization; Additive Manufacturing; Accessibility of supports)uuid:6de96f3e5ca24011bfe47e5e00d4eb56Dhttp://resolver.tudelft.nl/uuid:6de96f3e5ca24011bfe47e5e00d4eb56TThe Darcy method for Topology Optimisation of pressure actuated compliant mechanismsvFrouws, Jan (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Precision and Microsystems Engineering)Langelaar, Matthijs (mentor); Kumar, Prabhat (graduation committee); Tichem, Marcel (graduation committee); Nijssen, Joep (graduation committee); Delft University of Technology (degree granting institution)3 This work introduces a new method to deal with design dependent pressure loads in Topology Optimisation (TO) using the SIMP material model. A pronounced focus is on optimising pressure actuated compliant mechanisms. The difficulty herein is the interpretation of the pressure boundary in a TO design. In TO the boundaries are blurry, because of the filtering of the design variables, which is necessary to prevent checkerboarding. Another reason why the boundary is poorly defined is that the optimisation starts from an equally distributed grey, where black and white respectively are solid and void, so the boundary is either the domain boundary or not defined in early iterations of the optimisation. <br/>The methods proposed in literature often try to find the voidsolid interface exposed to the pressure source to apply the loading from a pressure line directly. The method proposed in this work, appropriately called the Darcy method, first calculates the pressure field by using Darcy's law governing the flow through porous media and the associated pressure drop. A flow coefficient is introduced that decreases if the virtual element density increases. This results in a design dependent pressure field that can be solved using the Finite Element Method (FEM), which can then be translated to consistent nodal forces that are applied to the TO problem. A drainage coefficient has also been introduced to make sure that the pressure is drained entirely to the environment pressure over the first encountered voidsolid interface exposed to the pressure source. The Darcy method has proven to function well in several test cases. The method has been thoroughly tested using several parameter sweeps on a clamping problem objective. The parameters whose influence is examined are: the initial condition, the density threshold value, flow coefficient gradient at the threshold, output spring stiffness and the volume fraction. <br/>Subsequently, some alternative TO problems are solved showing the diversity of the method. In perspective of future research, the Darcy method can function as a great tool to research load sensitivities by tuning the pressure field control parameters. The extension of the Darcy method to 3D or to several load cases comes naturally but has not been tested in this work, this is also recommended for future research.Topology optimization; Design dependent loading; Pressure load; Darcy's law; Compliant Mechanisms; Soft Robotics; Darcy's method
20190930)uuid:0072521f9aef49cb83eed26013a99b47Dhttp://resolver.tudelft.nl/uuid:0072521f9aef49cb83eed26013a99b47/Topology Optimization of Optomechanical SystemsxKoppen, Stijn (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Precision and Microsystems Engineering)"Langelaar, Matthijs (mentor); de Vreugd, J (graduation committee); van Keulen, Fred (graduation committee); van der Kolk, Max (graduation committee); van Kempen, Floris (graduation committee); Herder, Just (graduation committee); Delft University of Technology (degree granting institution)The stringent and conflicting requirements of optomechanical instruments and the everincreasing need for higher resolution and quality imagery demands a tightly i< ntegrated design approach. The aim of this study is to drive the thermomechanical design of multiple components of an optomechanical instruments by the system s optical performance. This work addresses the combination of structuralthermaloptical performance analysis and multicomponent topology optimization while taking into account both component and system level constraints. A 2D twomirror example demonstrates that the proposed approach is able to improve the system s spot size error by 95% compared to uncoupled system optimization to below the system's diffraction limit.topology optimization; Multidisciplinary Design Optimization; system optimization; optical instrumentation; optomechanics; thermoelasticity; structuralthermaloptical performance analysis
20180419)uuid:7812946d10934e59b96cf68ab4d0ac96Dhttp://resolver.tudelft.nl/uuid:7812946d10934e59b96cf68ab4d0ac96IDesign of actively controlled heat exchangers using topology optimizationNMohanachandran, Hari (TU Delft Mechanical, Maritime and Materials Engineering)van Keulen, Fred (mentor); van der Kolk, Max (mentor); Smulders, Patrick (mentor); Heck, Dennis (mentor); Delfos, Ren (graduation committee); S.H., Hossein Nia Kani (graduation committee); Delft University of Technology (degree granting institution)=An active fluid heat exchanger can be controlled effectively using Peltier elements to condition the temperature of the fluid flowing through the heat exchanger. The thermal resistance of the heat exchanger can be reduced to increase the speed of controlling the fluid's temperature. Topology optimization is used in this study to find the geometry of a heat exchanger with reduced thermal resistance. <br/>The design of a heat exchanger using topology optimization requires the coupling of the fluid flow equations and the energy equation in a finite element model with a continuous design variable. The existing optimization models perform well when the goal of the optimization problem is to minimize viscous dissipation. A weighted sum multiobjective function is however necessary to optimize the thermal performance of a design, and the correct choice of weights to meet design specifications is difficult to arrive at. <br/>The drawback in the existing model is that the conductivity distribution is defined as a function of the design variable of the optimization problem. This results in infeasible designs when the goal of the optimization problem is to minimize only thermal resistance, and this is demonstrated with several numerical examples along with a motivation for a new formulation. <br/>A new formulation for conductivity distribution is proposed in this thesis. The new formulation defines the conductivity distribution in terms of the velocity field in the design domain. The new formulation is capable of significantly reducing the thermal resistance of the heat exchanger, and this is demonstrated with a numerical example. Finally, a 3d design case is implemented, the results of the optimization routine are postprocessed and the performance of the baseline design from ASML is compared with the topology optimized design. <br?design; heat exchangers; thermal control; topology optimization
20200101Mechanical Engineering)uuid:0db4da1e07e5433fa2613dc0cd6abfc0Dhttp://resolver.tudelft.nl/uuid:0db4da1e07e5433fa2613dc0cd6abfc0bPostProcessing of Topology Optimized Results: A method for retrieving smooth and crisp geometriesJSwierstra, Marco (TU Delft Mechanical, Maritime and Materials Engineering)Langelaar, Matthijs (mentor); Gupta, Deepak (mentor); Hendriks, M.A.N. (graduation committee); Delft University of Technology (degree granting institution)X Structural design optimization is the process of obtaining an optimized structure while satisfying a set of criteria. The process can be divided into three stages: topology optimization (stage one), geometry extraction (stage two) and shape optimization (stage three). The last two stages are regarded to be the postprocessor of topology optimized results and this MSc. Thesis proposes a new method for this par< t. At stage one, topology optimized results show unwanted features, namely jagged boundaries (i.e. poor smoothness) and intermediate densities (i.e. poor crispness). The postprocessor should overcome these unwanted properties.<br/>During postprocessing the geometry is described implicitly by a Level Set Function (LSF). The zerolevel contour of the LSF describes the actual geometry. The LSF is constructed by summing a set of Radial Basis Functions (RBFs) each multiplied with a weight, resulting in a smooth summation. At stage two, a geometry is extracted by setting up and solving a set of equations linking the RBFs to the densities obtained at stage one.<br/>At stage three, a shape optimization is done to compensate the loss of structural performance, which resulted from translating the densities to an LSF at stage two. The geometry described by the LSF does not match the mesh created for stage one. A fictitious domain method called the Finite Cell Method (FCM) is used to perform a structural analysis on the nonmatching mesh. A sensitivity analysis is done to provide gradient information to the gradientbased optimizer, the Method of Moving Asymptotes (MMA). Controlling the slope of the LSF is needed to make sure the sensitivities do not become zero throughout the domain. The maximum possible slope of the LSF can be fixed by setting a bound on the weights of the RBFs. Furthermore, intermediate densities are penalized such that these provide relatively low stiffness compared to its material use.<br/>Several case studies are done using the proposed method. The postprocessor: (1) improves the smoothness due to the use of the smooth LSF, (2) decreases the amount of intermediate densities by an average factor of 5.5 and (3) achieves an average 10\% improve in performance between stage two and three. The computation time is strongly problem dependent, test cases are either: slower, equally fast or faster than the topology optimization of stage one.Otopology optimization; shape optimization; Level Set Method; Finite Cell Method
20180901)uuid:5cba2fb3ed0b4d1eb3c999b585ebb2beDhttp://resolver.tudelft.nl/uuid:5cba2fb3ed0b4d1eb3c999b585ebb2be_An investigation of the effect of initial design choices in densitybased topology optimizationvan Schoubroeck, Joachim Kinley (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Precision and Microsystems Engineering)Langelaar, Matthijs (mentor); Gupta, Deepak (graduation committee); Delft University of Technology (degree granting institution)[topology optimization; initial design; initial guess; starting guess; starting design; SIMP
20181231PME)uuid:95ae533b4b374d4a92f5029735a09265Dhttp://resolver.tudelft.nl/uuid:95ae533b4b374d4a92f5029735a09265;Topology Optimization of Geometrically Nonlinear Structures>Holtzer, Bart (Mechanical, Maritime and Materials Engineering)Wvan Keulen, Fred (mentor); Delft University of Technology (degree granting institution)So far, structural topology optimization has been mainly focused on linear problems. Much less attention has been paid to geometrically nonlinear problems, although it has a lot of interesting applications. The objective of this work is to implement a method to solve topology optimization problems under finite displacements and rotations. The main focus is on designing stiff structures, but also an outlook is presented on the design of structures that follow a prescribed equilibrium path.<br/><br/>The NewtonRaphson incrementaliterative procedure is implemented to solve nonlinear problems. Arclength control is used to be able to overcome limit points and to obtain faster convergence. It is shown by means of numerical experiments that this method leads to correct results.<br/><br/>Since nonlinear analysis, especially in combination with topology optimization, is computationally expensive, an attempt is made to develop a new reduction method. This method uses load dependent Ritz vectors as a reduced basis and was originally used in linear dynamic problems. However, it is demonstrated that this method will in g< eneral not lead to accurate results in nonlinear static problems. This is due to the fact that deformation modes that are not excited by the external force, cannot be described by the basis.<br/><br/>The topology optimization process is implemented without reduction method. An adjoint formulation is derived to obtain sensitivities in a computationally efficient way. By means of several examples of endcompliance minimization, it is demonstrated that in most cases, especially for shell structures, this method leads to better performing designs than topology optimization based on linear analysis.topology optimization; geometrically nonlinear structures; Ritz vectors; nonlinear mechanics; arclength control; prescribed equilibrium paths; shells; Reduced order model)uuid:cabc53d09c174412868e850d4a1efc58Dhttp://resolver.tudelft.nl/uuid:cabc53d09c174412868e850d4a1efc58FAdditive Manufactured Glass Connection: The polyester glass connection7Koenen, Willem (Architecture and the Built Environment)qKnaack, Ulrich (mentor); Louter, Christian (mentor); Delft University of Technology (degree granting institution)For this thesis an additively manufactured(AM) glass connection was researched. The aim was to see if it was possible to use plastic based AM for end use parts in the faade. This was done in three parts, which are presented in this thesis. The first part consists of research in all currently available technology that could be used to create such a connection. The following section is about the design process of the AM connection and its engineering. The final part of the research further validates the design by means of structural tests and a rough price comparison to already existing glass connections. <br/><br/>The first part of this research focused on glass connections, additive manufacturing and topology optimization. This was primarily literature research that gave insight into which existing bases could be used to build on further in this project. The research showed that the spider profile has the most potential for further development and become a new sort of connection. The research also provided insight in the different AM technology s that could make the new connection. That research was necessary to selected the final production method an used materials. In the final part of the literature study insight in topology optimization was obtained to design the connection with the help of topology optimization.<br/><br/>The findings from the first part of the research provided the basis for the design and engineering processes of this new AM glass connection. The connection was designed with the help of topology optimization. The idea behind the optimization was to reduce the stresses in the glass and to attach the connection to the glass without drilling. The result of the optimization was a connection that has the shape of a line and that would be bonded to the glass with Transparant Silicone Structural Adhesive better known as TSSA. This connection consists of a number of different elements. The first is a separate AM piece that would be laminated to the glass and could be inserted into the remainder of the joint that connects four corners of four different glass plates. The second element is adapted to allow for the free movement of the glass panels by locally removing material so it would be weaker in one direction. Alternatively, it is given a power joint, which is a rubber joint that allows for movement in all directions. This connection was calculated multiple times to see how the connection would perform.<br/><br/>In the final part of this thesis the joint itself was researched to further validate the connection. This was done by making a prototype of the connection to see how everything could work and if it was actually suitable for production. For this validation, process a number of tests were done on smaller specimens to show how strong the material is and to give validation to the calculations. Finally, a small study was done in to the market potential of custom glass connections like this one by making pric< e comparisnos to currently existing spider profiles.HGlass; topology optimization; Facade; additive manufacturing; ConnectionBuilding Technology)uuid:01b37bf697da423b9d47a3623d03b201Dhttp://resolver.tudelft.nl/uuid:01b37bf697da423b9d47a3623d03b201UA Practical Application of Topology Optimization for Heat Transfer and Fluid DynamicsScholten, T.C.van der Kolk, M. (mentor)Topology optimization is widely used within the academic environment. It is however not yet a standard design tool within the commercial industry. My research aims to shorten this gap by applying a topology optimization for an industrial design load. The design load is from a Printed Circuit Assembly (PCA) that requires active cooling in order to function within specification. The PCA is cooled with a water cooled plate. The topology optimization is used to find the optimal distribution of the cooling channels such that optimal cooling is provided. The first part of my research describes a conceptual design for the cooling of the PCA. The thermal behavior of the design is predicted with a Finite Element analysis and the results are verified by means of an experimental measurement setup. The second part is the practical application of the topology optimization. The topology optimization is applied to the heat transfer and fluid dynamics that govern the behavior of the cool plate. Multiple water inlet and outlet positions are considered. A comment is given on which is the best performing design. An experimental measurement setup is created with the optimized design, and the difference in performance between the optimized and the baseline design is measured.WTopology Optimization; Fluid Dynamics; Heat transfer; ASML; Prototype; Measurement; FEM.Mechanical, Maritime and Materials Engineering,Precision and Microsystems Engineering (PME))uuid:bfafd16380984829b34d290dc2e1b5faDhttp://resolver.tudelft.nl/uuid:bfafd16380984829b34d290dc2e1b5fatTowards Topology Optimization for constructing Compliant Optical Mount Mechanisms by means of Additive ManufacturingSmorenberg, P.G.J./Langelaar, M. (mentor); van Keulen, A. (mentor)kOptical systems in high precision equipment become increasingly more complex due to the raising number of optical mounts used for mounting and positioning of optical components. Additional, the installation of electronics and inert gas purging systems to protect the optics against the abrasive optical beam extends the amount of components in the optical system, while keeping the surface area of the overall optical system as small as possible. Recent developments in optical systems lead to innovations of optical flexure mounts towards a more compact, accessible and userspecific system with integrated functionality at consistently high standards of optical stability. Additive manufacturing, commonly named 3D printing, offers new possibilities of designing optical flexure mounts, since the layerwise manufacturing approach allows the production of highly complex parts compared to traditional processes. Topology optimization is a mathematical design tool that can help to design these increasingly complex parts, such as the optical mount, by computing optimal material distributions for a given objective with a determined set of constraints and boundary conditions. The thesis objective is bilateral: The first research objective investigates the design of compliant mechanisms for industrial optical mounts by means of additive manufacturing. The second research objective investigates the suitability of Topology Optimization for designing compliant mechanisms for optical mounts. This research is providing insights into the working principles of optical mounts and compliant mechanisms as well as topology optimization and additive manufacturing. The present case studies demonstrate and evaluate topology optimization design techniques for compliant structures and mechanisms. Further, the use of additive manufacturing for compliant optical mounts mechanisms designs is evaluated.3D printing; additive manufacturing; compliant mechanisms; topology< optimization; optical mount; compliant optical mount mechanisms!3D printing exploration programme)uuid:ac8d7262a19a4a85bb11e1cdfb4ab411Dhttp://resolver.tudelft.nl/uuid:ac8d7262a19a4a85bb11e1cdfb4ab411SA Substructuring Method to Apply Topology Optimization to SystemComponent Problems Stolk, M./Langelaar, M. (mentor); Van Keulen, A. (mentor)Since its introduction, Topology Optimization (TO) has been applied to a broad range of design cases. TO is a material distribution method which finds the optimal material layout for a given design space while upholding given constraints and boundary conditions. This has made the method popular in structural mechanics where it is used to find concept designs for a wide range of structural problems. In this thesis TO will be applied to a structural case inspired by a problem found in ship design: the connections between the hull and the decks as well as the connections between decks. These connections have a significant influence on the behaviour of the ship as they determine the stiffness of the ship. With TO it is possible to find new designs for these connections. Applying TO on these connections is not straightforward as they are a part of a large system, and the interaction with the system must be taken into account for realistic results. This complicates the transformation of the ship response into boundary conditions for the TO model. In this thesis this problem is translated into a general problem where the design region and the global model will be modelled as separate substructures.The Lagrange multiplier method is introduced in this thesis to couple the substructures with nonconforming meshes. Tests in this thesis show the advantages of the method, it is able to couple nonconforming substructures and the error between a coupled highly nonconforming structure (up to 6 times smaller elements between the substructures) and a single structure remains below 1%. However, the Lagrange multiplier method is not free of disadvantages: it introduces additional unknowns, it makes the system indefinite and gaps and penetrations can be present on the interface due to the weak compatibility, changing the stiffness of the interface. The optimization process is only applied to one substructure. The test results show that the coupling has an effect on the stiffness of the interface, resulting in a different design when the nonconformity between substructures increases. A bufferzone is introduced in order to exclude the interface elements from the optimization process and this will prevent the influence of coupling on the TO. The designs almost match perfectly with this buffer zone and the differences between the displacements and the compliance of the single structure case is _ 0.3%. Using static condensation it is possible to reduce the size of the system resulting in a reduction of the computational cost. The Degrees of Freedom (DoFs) of the global structures, and the Lagrange multipliers are removed, leaving only the DoFs of the substructure that is optimized. This will lead to a system that has the size of the model in the design region and which is unaffected by the size of the systems connected to it. The designs obtained using the condensed systems do not differ from the design obtained using the complete system, while the computational cost per iteration is greatly reduced and made constant. New steps are introduced that will add to the total computational time, such as constructing the condensed stiffness matrices. But these steps only need to be done once and this increase of computational cost is lower than the total reduction obtained. The method has been tested on a problem consisting of 4 substructures with nonconforming element sizes. With the correct bufferzone the designs found by TO are almost equal and the difference in compliance is low (_ 2.3%). The power of static condensation is also shown in this test case, the calculation time of the optimization process is reduced by 40 to 80 %. Concluding that a design region can be coupled as a substructure to an existing model< and optimized without substantially increasing the computational cost.qTopology optimization; Substructures; Lagrange multiplier method; nonconforming meshes; Systemcomponent problem
20170116&Precision and Microsystems EngineeringEngineering Mechanics)uuid:417d56f403674b60962c9a77790c1ee5Dhttp://resolver.tudelft.nl/uuid:417d56f403674b60962c9a77790c1ee56Topology optimization for submerged buoyant structuresPicelli, R. (University of Campinas); van Dijk, R. (FEM Engineerning); Vicente, W.M. (University of Campinas); Pavanello, R. (University of Campinas); Langelaar, M. (TU Delft Structural Optimization and Mechanics); van Keulen, A. (TU Delft Structural Optimization and Mechanics)9This paper presents an evolutionary structural topology optimization method for the design of completely submerged buoyant modules with designdependent fluid pressure loading. This type of structure is used to support offshore rig installation and pipeline transportation at all water depths. The proposed optimization method seeks to identify the buoy design that has the highest stiffness, allowing it to withstand deepwater pressure, uses the least material and has a minimum prescribed buoyancy. Laplace's equation is used to simulate underwater fluid pressure, and a polymer buoyancy module is considered to be linearly elastic. Both domains are solved with the finite element method. Using an extended bidirectional evolutionary structural optimization (BESO) method, the designdependent pressure loads are modelled in a straightforward manner without any need for pressure surface parametrization. A new buoyancy inequality constraint sets a minimum required buoyancy effect, measured by the joint volume of the structure and its interior voids. Solid elements with low strain energy are iteratively removed from the initial design domain until a certain prescribed volume fraction. A test case is described to validate the optimization problem, and a buoy design problem is used to explore the features of the proposed method.XBESO method; buoyancy; buoyant structures; subsea buoyancymodules; Topology optimization
20170511)uuid:66eb04e254a14c3390d8521c431ea538Dhttp://resolver.tudelft.nl/uuid:66eb04e254a14c3390d8521c431ea538ZA unified aggregation and relaxation approach for stressconstrained topology optimizationVerbart, A. (NLR  Netherlands Aerospace Centre; Technical University of Denmark); Langelaar, M. (TU Delft Structural Optimization and Mechanics); van Keulen, A. (TU Delft Structural Optimization and Mechanics)In this paper, we propose a unified aggregation and relaxation approach for topology optimization with stress constraints. Following this approach, we first reformulate the original optimization problem with a designdependent set of constraints into an equivalent optimization problem with a fixed designindependent set of constraints. The next step is to perform constraint aggregation over the reformulated local constraints using a lower bound aggregation function. We demonstrate that this approach concurrently aggregates the constraints and relaxes the feasible domain, thereby making singular optima accessible. The main advantage is that no separate constraint relaxation techniques are necessary, which reduces the parameter dependence of the problem. Furthermore, there is a clear relationship between the original feasible domain and the perturbed feasible domain via this aggregation parameter.RStress constraints; Singular optima; Constraint aggregation; Topology optimization
20170706)uuid:30658a6c96a9412c8386d94f5418c568Dhttp://resolver.tudelft.nl/uuid:30658a6c96a9412c8386d94f5418c568QAn additive manufacturing filter for topology optimization of printready designs$Additive manufacturing (AM) offers exciting opportunities to manufacture parts of unprecedented complexity. Topology optimization is essential to fully exploit this capability. However, AM processes have specific limitations as well. When these are not considered during design optimization, modifications are generally needed in postprocessing, whi< ch add costs and reduce the optimized performance. This paper presents a filter that incorporates the main characteristics of a generic AM process, and that can easily be included in conventional densitybased topology optimization procedures. Use of this filter ensures that optimized designs comply with typical geometrical AM restrictions. Its performance is illustrated on compliance minimization problems, and a 2D Matlab implementation is provided.yAdditive manufacturing; Design for manufacturing; Overhang angle; Printability; Support structures; Topology optimization)uuid:bfbe8b47b7fe45918ec21f10fd87958aDhttp://resolver.tudelft.nl/uuid:bfbe8b47b7fe45918ec21f10fd87958adComputational time issues of AM process simulations with a view to largescale topology optimizationMunro, D.P. (TU Delft Structural Optimization and Mechanics); Ayas, C. (TU Delft Structural Optimization and Mechanics); Langelaar, M. (TU Delft Structural Optimization and Mechanics); van Keulen, A. (TU Delft Structural Optimization and Mechanics)JAdditive manufacturing; Flow optimization; Overhang; Topology optimization)uuid:ca6c6409298c416ea38a3c2f56960c63Dhttp://resolver.tudelft.nl/uuid:ca6c6409298c416ea38a3c2f56960c63oIntegrating topology optimization in precision motion system design for optimal closedloop control performance(van der Veen, G.J. (TU Delft Structural Optimization and Mechanics; MIPartners BV); Langelaar, M. (TU Delft Structural Optimization and Mechanics); van der Meulen, Stan (ASML); Laro, Dick (MIPartners BV); Aangenent, Wouter (ASML); van Keulen, A. (TU Delft Structural Optimization and Mechanics)In pursuit of better accuracy, higher speed and larger scale, manufacturers of highperformance devices increasingly rely on components which have been designed with a multidisciplinary approach from the outset. In the context of motion systems, this means that for instance structural mechanics, control engineering and thermal analysis are considered early in the design. In addition, the prospect of producing freeform device components using additive manufacturing at full scale allows designers to even further refine components to a specific purpose, or even integrate multiple functions into a single component. The design freedom offered by additive manufacturing is far greater than that offered by traditional techniques. To exploit this freedom a topology optimization framework is proposed that allows to determine the optimal material quantity and distribution within a design volume. In particular, this article focuses on the closedloop control performance of a motion system component, while simultaneously ensuring that mechanical requirements are met. Based on an example, it is demonstrated that this leads to nontrivial and nonintuitive designs which provide improved performance at lower structural mass compared to eigenfrequency designs. The framework allows rapid development of prototype designs, which may eliminate some of the costly design iterations which are currently made in industrial practice.Closedloop performance; Design sensitivity analysis; Integrated design; Mechatronics; Motion systems; Topology optimization
20190901)uuid:ee2befd329cc40d29c57a0c7d098da3aDhttp://resolver.tudelft.nl/uuid:ee2befd329cc40d29c57a0c7d098da3aPHigherorder multiresolution topology optimization using the finite cell methodGroen, J.P. (Technical University of Denmark); Langelaar, M. (TU Delft Structural Optimization and Mechanics); Sigmund, O (Technical University of Denmark); Ruess, M. (University of Glasgow)This article presents a detailed study on the potential and limitations of performing higherorder multiresolution topology optimization with the finite cell method. To circumvent stiffness overestimation in highcontrast topologies, a lengthscale is applied on the solution using filter methods. The relations between stiffness overestimation, the analysis system, and the applied lengthscale are examined, while a highresolution topology is maintained. The computational cost associated with nested topology optimi< zation is reduced significantly compared with the use of firstorder finite elements. This reduction is caused by exploiting the decoupling of density and analysis mesh, and by condensing the higherorder modes out of the stiffness matrix.;Finite cell method; Higherorder FEM; Topology optimization
20171019)uuid:c65a8a115f724ef48cf06a27997e4617Dhttp://resolver.tudelft.nl/uuid:c65a8a115f724ef48cf06a27997e4617@Overhang free topology optimization applied to flow optimizationvan de Ven, E.A. (TU Delft Structural Optimization and Mechanics; NLR  Netherlands Aerospace Centre); Verboom, J.M. (NLR  Netherlands Aerospace Centre; Student TU Delft); Ayas, C. (TU Delft Structural Optimization and Mechanics); Langelaar, M. (TU Delft Structural Optimization and Mechanics); Maas, Robert (NLR  Netherlands Aerospace Centre); van Keulen, A. (TU Delft Structural Optimization and Mechanics))uuid:8d0eec42e3134b1f8338526f1967217fDhttp://resolver.tudelft.nl/uuid:8d0eec42e3134b1f8338526f1967217fQA computationally efcient process modelling approach for selective laser meltingYang, Y. (TU Delft Structural Optimization and Mechanics); Ayas, C. (TU Delft Structural Optimization and Mechanics); van Keulen, A. (TU Delft Structural Optimization and Mechanics))uuid:6a80cee8e86a4aeb904dd4675016c09fDhttp://resolver.tudelft.nl/uuid:6a80cee8e86a4aeb904dd4675016c09fBA semianalytical thermal model of selective laser melting process)uuid:82a90cb2241043abbb6092029d82aa1eDhttp://resolver.tudelft.nl/uuid:82a90cb2241043abbb6092029d82aa1elTopology optimization of part and support structures for additive manufacturing considering machining forces)uuid:ce32ae7cbd08482faecd211f7e1fae5eDhttp://resolver.tudelft.nl/uuid:ce32ae7cbd08482faecd211f7e1fae5eURadar network topology optimization for joint target position and velocity estimationIvashko, I. (TU Delft Microwave Sensing, Signals & Systems); Leus, G.J.T. (TU Delft Circuits and Systems); Yarovoy, Alexander (TU Delft Microwave Sensing, Signals & Systems)In this paper, we tackle the problem of selecting the radar node positions to provide an estimate of the target state vector with a prescribed accuracy. The topology optimization problem is formulated as selection of a fixed number of radar node positions from a set of available ones, where the radar observations are modeled by a general nonlinear model. We further propose a topology optimization framework for the simultaneous estimation of the multimodal parameter vector. In particular, the task of joint position and velocity estimation is considered. The feasibility of the proposed approach is demonstrated for several cost functions, namely the frame potential as well as the logdeterminant and maximum eigenvalue of the error covariance matrix.<br[Radar network; Topology optimization; Greedy optimization; Frame potential; Logdeterminant
20180825$Microwave Sensing, Signals & Systems)uuid:fc53cb2e5b45464cacb62e90bdbbcef9Dhttp://resolver.tudelft.nl/uuid:fc53cb2e5b45464cacb62e90bdbbcef9^Minimum compliance topology optimization of shell infill composites for additive manufacturingWu, J. (TU Delft Materials and Manufacturing); Clausen, Anders (Technical University of Denmark); Sigmund, Ole (Technical University of Denmark)6Additively manufactured parts are often composed of two substructures, a solid shell forming their exterior and a porous infill occupying the interior. To account for this feature this paper presents a novel method for generating simultaneously optimized shell and infill in the context of minimum compliance topology optimization. Our method builds upon two recently developed approaches that extend densitybased topology optimization: A coating approach to obtain an optimized shell that is filled uniformly with a prescribed porous base material, and an infill approach which generates optimized, nonuniform infill within a prescribed shell. To evolve the shell and infill concurrently, our formulation assigns two sets of design variables: One set defines the base and the coating, while the oth< er set defines the infill structures. The resulting intermediate density distributions are unified by a material interpolation model into a physical density field, upon which the compliance is minimized. Enhanced by an adapted robust formulation for controlling the minimum length scale of the base, our method generates optimized shell infill composites suitable for additive manufacturing. We demonstrate the effectiveness of the proposed method on numerical examples, and analyse the influence of different design specifications.^Additive manufacturing; Coating; Composite; Infill; Topology optimization; Twoscale structure
20191020)uuid:d3909cc34475484fa85345ab31f7a9e9Dhttp://resolver.tudelft.nl/uuid:d3909cc34475484fa85345ab31f7a9e9GA lightweight cart frame design that makes use of topology optimizationGevers, L.T.M.Herder, J.L. (mentor)dTopology optimization is a bioinspired optimization method based on the growth of bones. With this method, the optimal material distribution with the minimal amount of material for a product can be defined. This could help engineers to create innovative lightweight designs and get rid of benchmark and pervious design on which current designs are commonly based. The goal of this graduation project is to show that topology optimization is useful as a source of inspiration for commercial companies to create innovative lightweight designs. Therefore, a design assignment is performed for a baggage cart frame design. The new cart frame design is based on the topology optimization in 3D. In the end, the new design is compared with four concepts designed by the company to show that the use of topology optimization resulted in a lighter and more innovative design.XTopology optimization; bioinspired; leightweight design; commerical company; cart frame
Biomechanical)uuid:c16662b20925449f8368da8ad156eb26Dhttp://resolver.tudelft.nl/uuid:c16662b20925449f8368da8ad156eb26tOn the Assessment of Additive Manufacturing Potential in the Maritime Construction Sector: The Effect on Ship Designvan der Zalm, M.FHekkenberg, R.G. (mentor); Hopman, J.J. (mentor); Custers, K. (mentor)Additive manufacturing, colloquially known as 3D printing, is a production process that offers possibilities compared to conventional production methods. Current methods involve shaping or removing of material to create parts, where additive manufacturing adds material. Several industries have successfully implemented the technology showing improvements for components such as 50% weight reduction or better performance. These opportunities do not seem as relevant in the maritime construction sector, therefore determining the potential requires more detail. The goal of this report therefore is set as: Asses the potential for additive manufacturing in the maritime construction sector and show its effect on ships through case studies. This goal is realized by providing an overview of additive manufacturing capabilities, opportunities and challenges related to maritime technology. It is found that the most interesting opportunities are: " Weight reduction " Performance improvement " Part consolidation and integrated functionality " Customization To further analyse the potential, the effect on system engineering, ship design and mechanical engineering is considered. It is assumed that the effect is mostly on mechanical engineering level, where the added value shows through the effect additive manufacturing has on the shape and function a part fulfils. Cost and fitness models are created to be able to quantify the added value additive manufacturing has. These are applied to the components gathered from vessel data and brainstorm sessions with the project partners. After this filtering, optimization is considered for all of the selected components, based on the opportunities of additive manufacturing. To determine the possible weight reduction a case study is performed using topology optimization on a rudder. This confirmed that a weight reduction from literature of 25% and for a rudder further reduction up to 40% is possible. Fro< m selected components it is found through detailed analysis that fairleads are 10 times more expensive to print compared to the current pipebased design. Ladders, air gratings are examples where the costs are similar to the current design, so a more detailed analysis is necessary for a verdict on these components. The mast of an lightweight offshore vessel produced with additive manufacturing can be cheaper, lighter and faster in production than the current composite design also offering the option of optimizing for a certain eigenfrequency to improve radar movement. Finally, rudders can be produced at similar costs as the current design but when printed, have the opportunity to be printed in a custom shape. This means features such as a twisted rudder can be implemented without additional costs. A case study is also performed for printing the entire hull of vessels, with an assumed weight reduction. This weight reduction then leads to fuel reduction from which return of investment is calculated. It is found that printing hulls is not feasible, since the average return of investment time is 282 years. The costs of additive manufacturing have to be 4 times lower or the weight savings have to be 75% to reach payback times of 5 years for some vessels. The implications of this thesis are that a general model is available for analysing components for additive manufacturing. This means that if the market changes or other components are requested to be printed, an analysis can easily be made. This thesis is part of a project called a GRaduation Industry Project (GRIP) in collaboration with Damen, Feadship and TNO and two other graduate students, Jurrit Bersgma and Martijn Obers . The two other students focus on the topics of production and structures, providing a total overview of the potential of additive manufacturing in the maritime construction sector.GTopology Optimization; 3D printing; Additive Manufacturing; Ship Design
20211108Marine and Transport Technology[Marine Technology  Ship Design Production and Operation Track Ship Design Specialisation
SDPO.16.023.m)uuid:257dc92ad8df4b2d87156a69b4aa3dddDhttp://resolver.tudelft.nl/uuid:257dc92ad8df4b2d87156a69b4aa3dddXConsistent formulation in isogeometric topology optimization for structural applicationsSalden, P.H.W.Turteltaub, S.R. (mentor)Topology optimization is an automated design approach for structural applications that is gaining popularity in industry, including the aerospace sector. Resulting designs can be made suitable for traditional manufacturing techniques, although it is a technique that is particularly useful for nonconventional approaches such as additive manufacturing. The procedure allows for choosing a design objective, such as minimum compliance or maximum heat conduction. Given one or more constraints, the optimal distribution of material within a domain is computed. A popular topology optimization method is the socalled Solid Isotropic Material with Penalization (SIMP). It is traditionally implemented using piecewise constant density values, specified per element. One technical difficulty with this approach is the formation of checkerboardlike patterns where the material is assigned to one element while the adjacent elements contain no material. This issue has been circumvented through the application of filters that explicitly prevent the formation of checkerboards. However, as a result of the filtering process, the designs display structural members with relatively high thicknesses and, at the same time, the structural detail level is relatively low. Several authors in the scientific literature argue that this effect is beneficial from a manufacturing viewpoint. However, recent progress in manufacturing techniques, such as additive manufacturing (also known as 3Dprinting), allows to manufacture components with an increased level of detail and complexity. From this point of view, it is relevant to study optimization procedures that preserve the level of detail displayed by unfiltered designs. In this project, SIMP is implemented using Iso< geometric Analysis (IGA). In IGA, NonUniform Rational BSplines (NURBS) replace the Lagrange polynomials classically used in Finite Element Analysis (FEA). Through the use of Bzier extraction, implementation changes are confined to the shape routine . Rather than working with piecewise constant density values, density is consistently approximated using NURBS. A consistent gradient formulation is derived as well. The effects on checkerboard formation are studied. Instead of filtering, separate meshes are used for density and displacement definition. A displacement mesh is obtained by further refining the density mesh, such that the displacement representation is more accurate. Adequate procedures for Gaussian integration are determined. The treatment is limited to two dimensional minimum compliance problems. It is found that a consistent density representation using NURBS does not prevent checkerboard formation. However, the use of separate meshes for density and displacement diminishes checkerboards. It also generates more detailed designs than those produced by filters. Obtained compliance values are lower as well. Through the use of IGA, arclike geometries may be studied. At the same time, nonclassical checkerboard patterns are observed.Etopology optimization; isogeometric analysis; SIMP; Bzier extractionAerospace Engineering"Aerospace Structures and Materials)uuid:b068f81c15614733a07d05e60368184bDhttp://resolver.tudelft.nl/uuid:b068f81c15614733a07d05e60368184b)3F3D: Form Follows Force with 3D printingPrayudhi, B.:Turrin, M. (mentor); Knaack, U. (mentor); Ren, S. (mentor)GTopology optimization is the natural counterpart of additive manufacturing, many believes that the technology could revolutionize the way we manufacture our everyday products, changing the way we design and manufacture our products considering of how the process mimics the nature system of manufacturing and design, socalled the biomimicry design. However, the level of research for the application of the technology in the building industry is still far behind compared to other more advanced industry such as the aerospace or automotive. This research thesis explores the opportunities and the possibilities of using this relatively young technology in the building industry, by developing not only a new manufacturing process but also new design methodology for architecture projects. The objective of this research is to design a structural system for freeform envelope of building by utilizing the potential of additive manufacturing and using topology optimization as a design method to optimize the structural performance in comparison to the existing design and manufacturing process.btopology optimization; additive manufacturing; freeform envelope; gridshell structure; 3d printing&Architecture and The Built Environment)uuid:d61e191a51424ecab108b4d9ad655996Dhttp://resolver.tudelft.nl/uuid:d61e191a51424ecab108b4d9ad655996'GPU Computing for Topology Optimization
Dondorp, M.E.Langelaar, M. (mentor)% This report has been written to serve as an introduction to the basics of GPU computing for mechanical engineers working in the field of structural optimization. In this work, the ability of GPUs to reduce the computation time of topology optimization problems is investigated. The programming paradigm of data parallel computing is introduced. GPU programming particulars are discussed and architectural differences between CPU and GPU processors are highlighted. It is shown how linear algebra operations can be judged on their suitability towards a massively parallelmode of execution. Algorithms with a high computational intensity and regular memory access patternswill benefit the most from a parallel implementation on a GPU. The flexibility of the Python programming language may alleviate much of the difficulties of GPU programing. It is investigated if a hybrid Python/GPU framework is a feasible way of GPU computing in the context of structural optimization. Several ways to interface the GPU from Python are discussed. It is shown that it is possible< to execute linear algebra operations on the GPU from a Python context and good performance is possible. However, it is observed that interprocessor communication deteriorates the overall speedup if just one operation is to be accelerated. As a guidance problem, a topology optimization compliance minimization study is introduced. The theoretical framework is given and broken down into a chain of compute steps. By profiling a conventional implementation of topology optimization, it is shown that the solver dominates the computation time entirely. Iterative solvers for linear systems are discussed in the context of topology optimization. By preconditioning the system of equations, the required amount of iterations to solve the system can be reduced. Some GPU compatible preconditioning techniques are discussed. For a topology optimization problem, a Sparse Approximate Inverse preconditioner is found to perform best. Two available conjugate gradient solver implementations have been put to the test. It is shown that, on commodity hardware, an off the shelf conjugate gradient solver for the GPU can yield a speedup compared to a competitive off the shelf conjugate gradient solver for the CPU. For a topology optimization problem, a speedup of two has been observed.*GPU computing; CUDA; topology optimization*Precision & Microsystems Engineering (PME))uuid:73979d57fdc44002add5b172344537faDhttp://resolver.tudelft.nl/uuid:73979d57fdc44002add5b172344537faSFeasibility of Alternative Finite Element Formulations within Topology Optimization
Feitsma, J.W.Aragon, A.M. (mentor)zIn this work, topology optimization is used to obtain optimal designs with minimal compliance as the objective. The checkerboard problem, refers to a resulting optimal topology where the material is distributed in regions of alternating solid and void elements. It has been shown that these regions emerge due to higher stiffness of the checkerboard patterns compared to the stiffness of uniformly distributed material. In this work a study is performed on the feasibility of nontraditional finite element formulations to deal with the checkerboard problem. Two alternative finite element formulations were studied in this work. The main focus is given to the pversion of the finite element method, also referred to as pFEM. In addition, the mixedenhanced formulation of Kasper and Taylor is discussed briefly. These finite element formulations will be compared to the formulation commonly used. In this thesis the main research question is: Can the use of alternative finite element formulations in topology optimization be used to solve the checkerboardproblem? In this thesis is is shown that the pFEM does prevent checkerboards when elements with polynomial order p greater equal to 2 are used. When even higherorder elements are used the final designs do not change significantly compared to p=2. It was found that computational time increases significantly with the element order, without an increase in the design resolution. The mixedenhanced formulation does not alleviate the checkerboard problem. Although small changes in design are found compared to standard Q4, checkerboards are still observed. Finally it has been shown that local prefinement can be employed to locally alleviate checkerboards. Two strategies have been introduced, which based on the element densities, are able to locally change the element orders. Checkerboardfree designs are obtained using the minimum number of higherorder elements as possible. Although the concept of local prefinement was proven, the presented methods are not yet optimal. An increase in computation time is observed and user specified tolerances were used. Hence, there is still room for improvement.+Topology optimization; checkerboards; pFEM)uuid:e8e70eacb6b145618eee5b03013c4680Dhttp://resolver.tudelft.nl/uuid:e8e70eacb6b145618eee5b03013c4680]Mastering ElectroMechanical Dynamics of Large OffShore DirectDrive Wind Turbine GeneratorsKirschneck, M.Rixen, D.J. (promotor)5The ever growing population of human beings on eart< h introduces the challenge of providing affordable, sustainable energy for everyone. Emerging markets, such as China, India or Brazil, quench their thirst for cheap energy by fossil fuels and nuclear power. At the same time researchers from all over the globe warn the public of the advent of a new, civilisation threatening disaster: climate change. Over the last two centuries mankind has gotten used to cheap but polluting energy provided by burning coal, gas and oil. The challenge arises in the form of the transition of our current economy towards a sustainable way of living. Renewable energy sources such as wind, tidal currents, the sun and geothermal heat have seen enourmous growth rates since the early nineties, as they are seen as the best approach to overcome this challenge. Of these renewable energy sources, wind energy is one that has received major attention. In the quest for expanding wind energy capacity, focus has shifted towards the sea in recent years. The potential energy yield is higher offshore caused by higher average wind speeds. Maintenance and availability are key issues offshore, due to the more complex logistics. In recent years, the price of onshore wind energy has decreased to a level that is competitive with prices for energy from some types of fossil fuel. However, the prices for offshore wind energy remain above the ones of fossil fuels. It is, thus, not surprising that the reduction of offshore wind energy costs is one of the main innovation drivers within the wind industry. With the advent of offshore wind energy more and more companies started investigating a new turbine topology called directdrive wind turbines. This turbine type eliminates the gearbox found in other types of wind turbines, as this might lead to increased availability and lower maintenance costs. In the search for the best design of directdrive wind turbines, every part of the turbine is investigated, analysed, measured and optimised to improve the functionality of that part. At the heart of the turbine, where the mechanical is transformed into electrical energy, is the generator. Also this component needs to be optimised with respect to weight and efficiency. This thesis aims to find the structural design that optimally utilises the mass of the generator structure to minimise deformation. This is done for the dynamic loads encountered in the generator. Special focus is given to the interaction between the structural dynamics and the magnetic field. This is important as the interaction between these two physical domains can lead to unexpected dynamic behaviour of the system. In Part I of this thesis, the modelling techniques that accurately include the interaction between the structural part of the turbine and the magnetic field in the generator are introduced. These techniques can, for the first time, predict the modal parameter changes, including damping changes, due to the interaction by forming a monolithic eigenvalue problem of the coupled system. The model neglects certain nonlinear influences on the dynamics, such as hysteresis and saturation. Its ability to predict changes of the modal parameters is validated by vibration measurements of a magnetomechanical coupled system. Furthermore, this part develops new methods to handle huge magnetomechanical coupled models that emerge when magnetic fields and structural dynamics of a directdrive wind turbine are modelled. The bottleneck is the memory requirements of the monolithic formulation that makes it necessary to solve for all degrees of freedom simultaneously. Part II applies the techniques developed in Part I to the generator of the XD115, a 5 MW directdrive wind turbine and conducts the first twoway coupled analysis of such a generator type. The detailed dynamic analysis of the generator gives new insights in the dynamic behaviour of the generator. Furthermore, the eigenfrequencies, modes and possible causes for excitation are identified. An experimental validation of the XD115 models was conducted using insitu experimental and operation modal analyses. Various tech< niques are compared for the challenging task of exciting the rotor structure. In the second part of Part II, the loads identified during the dynamic analysis are used as load case for a structural optimisation. Topology and shape optimisation were used to identify the optimal mass distribution for the rotor structure that minimises the deformation in the air gap. This way, the weight of the structure could be reduced significantly without compromising the static and dynamic performance of the generator structure. During the optimisation the suitability and potential of topology optimisation for directdrive wind turbines was evaluated. Although the introduced methodology can be applied to any electric machine, the implications for directdrive wind turbine generators are most significant, as for these machines the ratio between produced torque and weight is especially high. Important influences on and encountered challenges for improving the design are collected to improve future turbine designs.Wind Turbine; Topology Optimization; MagnetoMechanical Coupling; Structural Dynamics; Generator; Model Reduction; Magnetic Field)uuid:4d22ccddf4e7458eb4557405eaba6245Dhttp://resolver.tudelft.nl/uuid:4d22ccddf4e7458eb4557405eaba6245JTopology optimization of 3D linkages with application to morphing winglets
De Jong, T.A.0De Breuker, R. (mentor); Gillebaart, E. (mentor)
Topology optimization is the process of optimizing both the material layout and the connectivity inside a design domain. The first paper on topology optimization dates back to 1904, when the Australian inventor Michell derived optimality criteria for minimum weight truss structures. In 1988 Bendse and Kikuchi published the pioneering paper "Homogenization approach to topology optimization", laying the foundation of numerical optimization methods for topology optimization. Since then, extensive research has been performed both in academia and industry trying to solve different topology optimization problems. Due to its general applicability, topology optimization has been applied to the design of many morphing aircraft structures including morphing leading edges, trailing edges, or both. It has also been applied to complete morphing wings. Morphing structures have the ability to change their shape throughout the flight. This allows for possible weight savings and/or drag reduction, resulting in a reduced fuel consumption. Despite the great interest in morphing winglets from both Airbus and Boeing, topology optimization has not yet been used to design morphing winglets, except for previous work done by E. Gillebaart and R. De Breuker. This thesis continues with the research by focusing on the following research objective: "Developing a software tool to design amechanism for morphing winglets, using groundstructure based topology optimization, by improving, extending, and expanding the previous 2D inhouse tool." The research in this thesis is based on previous work done by the faculty. The previous 2D tool is improved, its capabilities are extended and the tool is expanded to 3D. The current tool effectively demonstrates how topology optimization, based on the groundstructure approach, can be used to obtainmechanisms for morphing winglets. A two step optimization strategy is formulated, where the mechanism is designed in the first step and sized to obtain minimum weight in the second step. Both optimizations are done using the globally convergent method of moving asymptotes (GCMMA) optimizer, combined with the adjoint sensitivity technique. Due to the large rotations of the winglet, geometric nonlinearity is taken into account using the GreenLagrange strain measure. Various mechanisms for morphing winglets were successfully designed and sized both in 2D and in 3D. In 2D mechanisms were found where the cant angle could be regulated, in 3D mechanisms were found where both the cant angle and the toe angle could be regulated. An aerodynamic load case of 5 [kN] was defined. In 2D half of this loading was assumed to act on the mechanism, resulting in a minimum weight of 15< .0 [kg]. In 3D the minimum weight was found to be 48.0 [kg].otopology optimization; GreenLagrange; geometric nonlinearity; optimization; GCMMA; morphing; morphing winglet0Aerospace Structures and Computational Mechanics)uuid:e0482f8f4de7479c80be47d837d8fddfDhttp://resolver.tudelft.nl/uuid:e0482f8f4de7479c80be47d837d8fddf@Application of Advanced Cementitious Materials in Infrastructure
Shalom, I.{Hordijk, D.A. (mentor); Van der Veen, C. (mentor); Kolstein, M.H. (mentor); Reitsema, A.D. (mentor); De Waardt, H. (mentor)Advanced Cementitious Materials (ACM s) are products with materials found in conventional concrete (cement, silica fume, sand, superplasticizer, and water) plus distinctive materials like fibers (steel, carbon) and quartz. The superiority of ACM s in terms of strength, ductility, and durability marks it as high potential replacement of traditional concrete. The growing expansion of ACM applications and technical experience gained in the last two decades in counties including Japan, Germany, Austria, Australia, USA, Denmark, Canada, France, and the Netherlands results in new frontier of cement materials used in infrastructure. The economic feasibility of ACM s has been demonstrated in footbridges, outstanding bridges, and large precast series. Furthermore safety and durability of ACM s, especially of Ultrahigh performance concrete (UHPC) has been proven encouraging further research efforts. This research is one part of an ongoing research under the supervision of Professor D.A. Hordijk at the Technical University of Delft on the application of ACM s in infrastructure. The biggest potential for new infrastructure with ACM s is in precast girders and thin plates. Throughout utilizing the excellent properties of ACM s like UHPC, a new lighter weight, durable, efficient, and adaptable superstructure has been developed in this study to replace the existing traditional design of bridges in the nearby future. One example of the approach taken in this thesis is the benefit of long lifecycle. Due to dense matrix, which prevents the ingress of detrimental substances apply UHPC selectively in the superstructure where it required to sustain high level of durability. Another example of the mindset of this thesis is lightweight design, means material distribution follows the forces distribution. In this thesis the outcome of an extensive material study was an overview of the ACM s properties, time depended behavior, nonlinear behavior, design standards, and field of application. Based on the material study different parameters are analyzed to enhance the understanding of the behavior of structure with ACM. It has been found that structural elements from UHPC are far more efficient then their corresponded traditional concrete structures. The maximum crack size is significantly lower, the slenderness is much higher which result in higher efficiency and reduction of the dead loads. Also the shrinkage and creep of ACM s is studied. The timedepended imposed deformation of UHPC elements (plate, flange, truss member) with different sizes cause stresses in the model ends up as transverse cracks when the deformation is restrained. Based on the drawn conclusion of the parametric study, the design stage of the new ACM superstructure was initiated complying with requirements & boundaries according to the NEN norms and SETRA (French recommendation for UHPC). The new superstructure is 35% lighter than traditional solution, with efficient material distribution, built only from concrete, with elegant simple solutions. The low reliability of the fibers as replacement for reinforcement wellthoughtout in the design. Some suggestion for future research in the field of modular adaptable superstructure have promising potential as far as applying ACM s.Advanced Cementitious Materials; Ultra high performance material (UHPC); Strain hardening Cementitious concrete (SHCC); Fiber Reinforced Concrete (FRC); Concrete truss; hybrid superstructure; Topological optimization!Civil Engineering and GeosciencesStructural EngineeringConcrete Struc< tures)uuid:2aa17c5666a241c895fca1af50dc52ddDhttp://resolver.tudelft.nl/uuid:2aa17c5666a241c895fca1af50dc52dd<Fast topology optimization for transient mechanical problemsVan der Linde, T.M.Topology optimization is increasingly used as a design tool in engineering. Within structural mechanics, most applications focus on statics. An extension to timedomain (transient) dynamics will have many useful applications, but this is currently hindered by high computational costs. The goal of this research is to reduce these costs by applying model order reduction. In model order reduction, the full coordinates of a system are approximated by a much smaller number of reduced coordinates and associated basis vectors. A few options for these vectors will be discussed. It is shown that using loadbased methods results in high accuracy, especially the Ritz vector method. In the total optimization this leads to significant reduction of both CPUtime and memory requirements.dtopology optimization; timedomain dynamics; transient dynamics; model order reduction; Ritz vectors
20160107)uuid:6fba549900124708a25cc532da59e85cDhttp://resolver.tudelft.nl/uuid:6fba549900124708a25cc532da59e85c\Optimizing front metallization patterns: Efficiency with aesthetics in freeform solar cellsGupta, D.K. (TU Delft Structural Optimization and Mechanics); Langelaar, M. (TU Delft Structural Optimization and Mechanics); Barink, M (TNO); van Keulen, A. (TU Delft Structural Optimization and Mechanics)Freeform solar cells are cells of unconventional shapes (e.g. hexagonal, leafshaped etc). Their flexible shape adds to the aesthetics of the surroundings as well as allows to place them over objects where conventional solar cells might not fit. Evidently, these cells need to be efficient as well, and one of the important factors that controls their performance is the front metallization design. In this paper, we present the application of topology optimization (TO) to optimize the front metallization patterns for freeform solar cells. TO distributes the electrode material on the solar cell front surface in an efficient manner, such that the total power output is maximized. To demonstrate the capability of the proposed methodology, we use it to optimize front metal grids for several complex solar cell shapes e.g. circular, hexagonal, leafshaped, motorbike fairings, etc. The results presented here demonstrate the capability of TO to generate efficient designs for these freeform shapes.RFreeform; Front metallization; Optimal design; Solar cells; Topology optimization)uuid:c0d2658bf36f4d77884ef9392c115e62Dhttp://resolver.tudelft.nl/uuid:c0d2658bf36f4d77884ef9392c115e62ZTopology optimization for additive manufacturing with controllable support structure costsaPapadrakakis, M. (editor); Papadopoulos, V. (editor); Stefanou, G. (editor); Plevris, V. (editor)bAdvances in additive manufacturing (AM) allow economical production of components with unprecedented geometric complexity. This offers exciting opportunities for innovative designs, and particularly topology optimization has been identified as a key technique to fully exploit the capabilities of AM. However, also AM involves manufacturing restrictions, such as limitations on the inclination of overhanging parts. To deal with this problem, either sacrificial supporting structures can be added during the process, or only selfsupporting designs can be considered. Both approaches have disadvantages, as support structures add material and postprocessing costs, while demanding exclusively selfsupporting designs may impose strong restrictions on achievable performance. With current methods, designers are limited to a choice between these two extremes. To open up a wider range of designs, this paper presents and demonstrates a topology optimization formulation that allows the designer to find tradeoff solutions between design performance and support structure costs, considering both printing and removal costsTopology optimization; additive manufacturing; overhang angle; support structures; self< supporting designs; manufacturing restrictionsconference paper6National Technical University of Athens (NTUA), Greece)uuid:c49bb07ebf7048fd96b8f07d7c0c26f5Dhttp://resolver.tudelft.nl/uuid:c49bb07ebf7048fd96b8f07d7c0c26f5QTopology optimization of 3D selfsupporting structures for additive manufacturingBThe potential of topology optimization to amplify the benefits of additive manufacturing (AM), by fully exploiting the vast design space that AM allows, is widely recognized. However, existing topology optimization approaches do not consider AMspecific limitations during the design process, resulting in designs that are not selfsupporting. This leads to additional effort and costs in postprocessing and use of sacrificial support structures. To overcome this difficulty, this paper presents a topology optimization formulation that includes a simplified AM fabrication model implemented as a layerwise filtering procedure. Unprintable geometries are effectively excluded from the design space, resulting in fully selfsupporting optimized designs. The procedure is demonstrated on numerical examples involving compliance minimization, eigenfrequency maximization and compliant mechanism design. Despite the applied restrictions, in suitable orientations fully printable AMrestrained designs matched the performance of reference designs obtained by conventional topology optimization.rTopology optimization; Additive manufacturing; Overhang angle; Selfsupporting designs; Manufacturing restrictions
20180609)uuid:d6d66aceec2649719e3a024c21a56015Dhttp://resolver.tudelft.nl/uuid:d6d66aceec2649719e3a024c21a56015@Integrated front reargrid optimization of freeform solar cellsGupta, D.K. (TU Delft Structural Optimization and Mechanics); Barink, M (TNO); Galagan, Y (TNO); Langelaar, M. (TU Delft Structural Optimization and Mechanics)OFreeform solar cells expand solar power beyond traditional rectangular geometries. With the flexibility of being installed on objects of daily use, they allow making better use of available space and are expected to bring in new possibilities of generating solar power in the coming future. In addition, their customizable shape can add to the aesthetics of the surroundings. Evidently, freeform solar cells need to be efficient as well. One way to improve their performance is to optimize the metallization patterns for these cells. This work introduces an optimization strategy to optimize the metallization designs of a solar cell such that its performance can be maximized. For the purpose of optimization, we model an existing transparent freeform solar cell design, including front and rear electrode patterns, to validate it against previously published experimental results. The front and rear metallizations of this transparent freeform solar cell are subsequently redesigned using topology optimization. More than 50% improvement in output power is achieved by using topology optimization.ftopology optimization (TO); Finiteelement analysis; freeform cells; metallization; photovoltaic (PV))uuid:1e3df6936f9440668f0b76bcc2524157Dhttp://resolver.tudelft.nl/uuid:1e3df6936f9440668f0b76bcc2524157UDamage approach: A new method for topology optimization with local stress constraints*Verbart, A.; Langelaar, M.; Van Keulen, A.@In this paper, we propose a new method for topology optimization with local stress constraints. In this method, material in which a stress constraint is violated is considered as damaged. Since damaged material will contribute less to the overall performance of the structure, the optimizer will promote a design with a minimal amount of damaged material. We tested the method on several benchmark problems, and the results show that the method is a viable alternative for conventional stressbased approaches based on constraint relaxation followed by constraint aggregation.estress constraints; singular optima; constraint aggregation; local constraints; topology optimizationSpringer)uuid:f59b08e4c3e9400c9403f8129cd5b578Dhttp://resolver.tudelft.nl/uuid:f59b08e4c3e9400c9403f< 8129cd5b578oTopology optimization of lithium ion batteries: How to maximize the discharge capacity by changing the geometryXu, T.HLangelaar, M. (mentor); Van Kempen, F. (mentor); Van Keulen, F. (mentor)Discharge capacity is an important factor that determines the performance of lithium ion battery. The internal resistance of the electrodes influence the discharge capacity. As the electrode geometry influences its resistance, topology optimization can be applied to determine the electrode shape such that it has a minimal internal resistance and thus obtain the maximum discharge performance. The influences of different design parameters have been analysed by means of numerical case studies. Several penalty techniques have been used to make the final topology more realistic and easy to manufacture. The discharge capacity and capacity fade under different discharge current, different design structures and different optimization constraints are imposed and analysed. A three dimensional electrode model based on the topology optimization is built and simulated. The comparison between different optimization methods has been studied. topology optimization; batteries
20181015)uuid:ab7d64b19b6e45838ce175c05b9da443Dhttp://resolver.tudelft.nl/uuid:ab7d64b19b6e45838ce175c05b9da443@Structural Design Optimization of Vibration Isolating StructuresVan der Kolk, M.KDe Vreugd, J. (mentor); Van der Veen, G.J. (mentor); Langelaar, M. (mentor)
The design of high performance instruments often involves the attenuation of poorly damped resonant modes. These resonant modes are a limiting factor to the performance of these instruments. Current design approaches typically start from a baseline design and introduce stiffening or damping reinforce ments to tune and/or damp these modes. However, the influence on the structural damping of these reinforcements is difficult to predict and often results in trial and errorbased design approaches for the design of damping reinforcements. A common solution is to introduce viscoelastic material in baseline designs to increase structural damping. These materials dissipate energy when subjected to deformation and should therefore be located at positions which undergo large deformations during vibration. Typically, the viscoelastic material is placed in conventional (un)constrained layer damping configurations. However, to achieve optimized damping characteristics both the location as well as the geometry of viscoelastic material should be optimized. In this thesis, a multimaterial topology optimization routine is presented as a systematic method ology to develop structures with optimal damping characteristics. The proposed method applies a multimaterial, parametric level setbased approach to simultaneously distribute structural and vis coelastic material within the design domain. The developed optimization routine allows for the design of freeform, viscoelastic dampers without the limitation to conventional (un)constrained layer damp ing configurations and is thereby able to achieve improved damping characteristics. The structural loss factor is applied as a performance measure to compare the damping between different viscoelastically damped structures and as objective function during the optimization. The viscoelastic material behavior is represented by a complexvalued material modulus, which results in a complexvalued eigenvalue problem. The formulation of the structural loss factor is modified to account for the complexvalued eigensolutions, resulting in accurate assessment of the structural loss factor for designs containing viscoelastic material with high material loss factors. The optimization routine maximizes the structural loss factor for single or multiple selected eigen modes. An adjoint sensitivity analysis is performed to provide an exact expression for the structural loss factor sensitivity. Based on this sensitivity information, the optimization routine is able to de velop structures with optimized loss factors for the specified eigenmodes. The method is also able to generate damp< ing solutions for existing designs containing badly damped resonant modes.viscoelastic damping; topology optimization; multimaterial optimization; level set method; loss factor; modal analysis; constrained layer damping)uuid:08481ec6d6df4162b2548b99eeccc6d1Dhttp://resolver.tudelft.nl/uuid:08481ec6d6df4162b2548b99eeccc6d1(Topology Optimization of Heat ExchangersPapazoglou, P.Heat exchangers have long been used in a wide variety of industrial applications, such as for energy recovery from byproducts, temperature regulation in chemical processes, refrigeration, or cooling of car engines. Typically, each application requires a different type of heat exchanger such as, tube, shell, with/without phase change, mixing/non mixing etc. heat exchangers. Due to their importance, there has been an ongoing interest in reducing the perational/constructional costs and increasing the efficiency. A lot of research has be done in optimizing certain features of heat exchangers (e.g. tube dimensions, fin thickness etc.), but so far none of them investigates the optimization of the whole topology of a heat exchanger. The aim of this thesis is to optimize the structure of a two flow heat exchanger, by means of topology optimization. More specifically we aim to maximize the efficiency of heat transfer, given some predefined pressure drop and dimension constraints. These constraints are necessitated by the need of achieving a reduced operating (pressure drop) and manufacturing dimensions) costs. A heat exchanger, being a multiphysics system, can be described by two physical phenomena: the flow of the fluid and the heat transfer. In this study we focus on heat exchanger governed by an isothermal and incompressible Stokes flow with low Reynolds number, while the heat transfer is assumed to be advectiveconductive heat transfer, without internal heat generation, characterised by a relatively high Peclet number. We evaluate two novel models for topology optimization of heat exchangers; the Fluid Tracking Model and the MultiMaterial Model. Throughout the experimental evaluation we saw that the MultiMaterial Model performs best. The Fluid Tracking Model did not produce optimal results and was unable to enforce nonmixing designs. The MultiMaterial Model optimized designs that maximized the heat transfer surface area between the fluids. Furthermore the designs illustrated a wall at the interfaces of the two fluids, keeping the two flows separated. Both 2D and 3D cases were studied. The 3D optimal results achieved a moderate improvement in performance over a simple design of a concentric tube heat exchanger.Atopology optimization; Heat exchanger; multiflow; multimaterial)uuid:c72b19d18d454c3ba8af238bca2ccb98Dhttp://resolver.tudelft.nl/uuid:c72b19d18d454c3ba8af238bca2ccb98VStructural optimization for materially informed design to robotic production processesBier, H.H.; Mostafavi, S.Hyperbody s materially informed DesigntoRoboticProduction (D2RP) processes for additive and subtractive manufacturing aim to achieve performative porosity in architecture at various scales. An extended series of D2RP experiments aiming to produce prototypes at 1:1 scale wherein design materiality has been approached from both digital and physical perspectives were recently implemented. At digital materiality level, a customized computational design framework for compression only structures has been developed, which was directly linked to the robotic production setup. This has enabled the systematic study of physical materiality, which cannot be fully simulated in the digital medium. The established feedback loop ensured not only the development of an understanding for material properties in relation to their simulated and real behaviours but also allowed to robotically additively deposit and/or subtractively remove material in order to create informed material architectures at 1:1 scale.[Materially Informed Design; Robotic Production; Topological Optimization; Material BehaviorScience Publications)uuid:ec565db0344548c880590fad62aea7f7Dhttp://resol< ver.tudelft.nl/uuid:ec565db0344548c880590fad62aea7f72Topology optimization using the Finite Cell MethodGroen, J.P.*Ruess, M. (mentor); Langelaar, M. (mentor)`The ongoing demand for better performing designs, has resulted in an increase in the complexity of topology optimization problems. Traditionally, the majority of the corresponding computational cost comes from solving the analysis equations using linear finite elements (FE). In this thesis a topology optimization method is presented, that is based on the finite cell method (FCM). This higherorder fictitious domain method is, due to its decoupled geometry, integration, and analysismesh well suited for largescale topology optimization, and reducing its corresponding computational cost. The use of a decoupled density and analysis mesh greatly reduced the computational cost of topology optimization compared to linear FEM. Especially in 3D topology optimization examples, the computational cost has been decreased by more than a factor 10, while maintaining a highresolution in the density field. The use of a larger lengthscale can reduce the computational cost even more, which is especially beneficial for robust topology optimization. It is identified that the choice of the analysis system completely depends on the complexity of the optimization problem. Simple optimization problems showed great increase in computational efficiency using relatively low polynomial degree (p= 1, 2, 3), combined with more density elements per finite cell. For more difficult topology optimization examples, such as problems were the boundary conditions have to be enforced in the weak sense, or stressconstrained topology optimization, a more accurate analysis system is required, hence a larger polynomial degree should be used.Ctopology optimization; finite cell method; computational efficiency+Mechanics, Aerospace Structures & Materials)uuid:ee24b1865db64c57aa503b736110ff2aDhttp://resolver.tudelft.nl/uuid:ee24b1865db64c57aa503b736110ff2aTopology Optimization with Stress ConstraintsVerbart, A.Van Keulen, F. (promotor)This thesis contains contributions to the development of topology optimization techniques capable of handling stress constraints. The research that led to these contributions was motivated by the need for topology optimization techniques more suitable for industrial applications. Currently, topology optimization is mainly used in the initial design phase, and local failure criteria such as stress constraints are considered in additional postprocessing steps. Consequently, there is often a large gap between the topology optimized design and the final design for manufacturing. Taking into account stress constraints directly into the topology optimization process would reduce this gap. Several difficulties arise in topology optimization with local stress constraints which complicate solving the optimization problem directly. \chap{litreview} discusses these difficulties, and reviews solutions that have been applied. Two fundamental difficulties are: (i) the presence of singular optima, which are true optima inaccessible to standard nonlinear programming techniques, and (ii) the fact that the stress is a local state variable, which typically leads to a large number of constraints. Currently, the conventional strategy to circumvent these difficulties is to apply (i) constraint relaxation, which perturbs the feasible domain to make singular optima accessible, followed by (ii) constraint aggregation to transform the typically large number of relaxed constraints into a single or few global constraints thereby reducing the order of the problem. Although there is no consensus on the exact choice of aggregation and relaxation functions and their numerical implementation, in general, this approach introduces two additional parameters to the problem: an aggregation and a relaxation parameter. Following this approach, one solves an alternative optimization problem with the aim of finding a solution to the original stressconstrained topology optimization. The feasible domain of th< is alternative optimization problem is related to the original feasible domain via these parameters. In Chapter 2, we investigated the parameter dependence of this alternative optimization problem on an elementary twobar truss problem. It was found that the location of the global optimum of this alternative optimization problem with respect to the true optimum depends in a nontrivial way on these problem parameters (in their range of application); i.e., for a given parameter set, it is difficult to predict the influence of changing one of the parameter values, and if this change will result in a feasible domain in which the global optimum is closer to the true optimum. This complicates determining optimal parameter values \emph{a priori} which, in addition, are problemdependent. In Chapter 3, we investigated the effect of design parameterization, and relaxation techniques in stressconstrained topology optimization. An elementary numerical example was considered, representing a situation as might occur in densitybased topology optimization. As previously observed in truss optimization, we found that a global optimum of the relaxed optimization problem may not converge to the true optimum as the relaxation parameter is decreased to zero. In this thesis, we present two novel approaches: a unified aggregation and relaxation approach in Chapter 4, and the damage approach in Chapter 5. In the unified aggregation and relaxation approach, we applied constraint aggregation such that it simultaneously perturbs the feasible domain, and makes singular optima accessible. Consequently, conventional relaxation techniques become unnecessary when applying constraint aggregation following this approach. The main advantage is that the problem only depends on a single parameter, which reduces the parameter dependency of the problem. The damage approach is presented as a viable alternative for conventional methodologies. Following the damage approach stress constraint violation is penalized by degrading material where the stress exceeds the allowable stress. Material degradation affects the overall performance of the structure, and therefore, the optimizer promotes a design without stress constraint violation. Similar to conventional constraint aggregation techniques a large number of local constraints can be controlled by imposing a single or a few global constraints. Both novel approaches are validated on elementary truss examples and tested on numerical examples in densitybased topology optimization. In contrast to the conventional strategy of relaxation followed by aggregation, there exists a clear relationship between the perturbed feasible domain and the original unperturbed feasible domain in terms of a single problem parameter.TTopology Optimization; Stress Constraints; Structural Optimization; Material failure
20150703)uuid:8bf193c3eece4fc1a25906ae5d275f45Dhttp://resolver.tudelft.nl/uuid:8bf193c3eece4fc1a25906ae5d275f45 Innovative joints for gridshellsVan der Linden, L.P.L.ZRots, J.G. (mentor); Hendriks, M.A.N. (mentor); Terwel, K.C. (mentor); Hofman, S. (mentor)Additive manufacturing is a production technique that builds up successive layers of material to create a 3D object from a digital model. With additive manufacturing design freedom is offered, which enables new opportunities for structural engineers and designers. This new opportunity is applied to design and produce structural joints for gridshells in an innovative way. Topology optimization is used to minimize the weight of the joints. This resulted in a weight reduction of almost 70 % for the Z?oty Tarasy gridshell. Moreover, improved solutions for the detailing of the joints are found. This reduces the labour intensity and it speeds up the erection process. Although the use of additive manufacturing for structural joints for gridshells is not cost efficient yet, it can be in the near future when printing speed goes up and material costs go down. With increased knowledge of the applied design and production method, it might become economically and technically feasi< ble to produce structural joints in gridshells by additive manufacturing.additive manufacturing; 3D printing; joints; gridshells; lightweight structures; weight reduction; topology optimization; innovation#Structural and Building Engineering)uuid:3243480a18454ea0bdc96f928405f561Dhttp://resolver.tudelft.nl/uuid:3243480a18454ea0bdc96f928405f561NAxisymmetrical topology optimization of an FPSO main bearing support structure
Van Vliet, E.Kiminski, M.L. (mentor)A study in the application of topology optimization to problems of realtive nature, as found in the load distribution within an FPSO main bearing.ztopology optimization; structural mechanics; relative constraints; method of moving asymptotes; FPSO; convex approximation"Ship structures and hydromechanicsShip and offshore structures52.009507, 4.360515)uuid:b0636cc5ac6745399971f427c24efc77Dhttp://resolver.tudelft.nl/uuid:b0636cc5ac6745399971f427c24efc77DTopology optimization considering designdependent Stokes flow loadsPicelli, R. (University of Campinas); Vicente, W.M. (University of Campinas); Pavanello, R. (University of Campinas); van Keulen, A. (TU Delft Structural Optimization and Mechanics)ELi, Qing (editor); Steven, Grant P. (editor); Zhang, Zhongpu (editor)This article presents an evolutionary topology optimization method for mean compliance minimization of structures under designdependent viscous fluid flow loads. The structural domain is governed by the elasticity equation and the fluid by the incompressible Stokes flow equations. When the modelling of a system consists in the interaction of multiple domains, the classic densitybased topology optimization methods become arduous within the framework of dealing with the moving multiphysics loads and interfaces, due to the considerable volume of intermediate density elements. Herein it is suggested an alternative methodology to handle this type of loading problems. With an extended Bidirectional Evolutionary Structural Optimization (BESO) method, designdependent Stokes flow loads are modelled straightforward during the optimization procedure. The discrete nature of the method allows both fluid and structural domains to be modelled separately in each step of the optimization. In order to validate the methodology, only small structural displacements and a simple staggered fluidstructure interaction algorithm are considered in this paper. Primary results are shown for a 2D flexible structure immersed in an incompressible viscous flow channel.STopology optimization; Penalization; Manufacturability; Transient thermomechanicalUniversity of Sydney)uuid:6f09726b1b2c4a118f589b5f323105cdDhttp://resolver.tudelft.nl/uuid:6f09726b1b2c4a118f589b5f323105cdZTopology optimization of a transient thermomechanical problem using material penalization(van de Ven, E.A. (TU Delft Structural Optimization and Mechanics; NLR  Netherlands Aerospace Centre); Hooijkamp, E.C. (TU Delft Structural Optimization and Mechanics); Langelaar, M. (TU Delft Structural Optimization and Mechanics); van Keulen, A. (TU Delft Structural Optimization and Mechanics)VDesigning transient thermal mechanical systems is a challenging task. Material can have many different functions: it can provide heat capacity, heat conduction, mechanical stiffness or even function as an actuator. Topology optimization can provide the engineer with valuable insight on such a problem. One of the most popular topology optimization approaches is the density method. This method is applied to a transient thermal mechanical problem. In order to ensure manufacturability, penalization is applied to suppress intermediate densities in the final design. However, for transient thermal mechanical optimization problems, conventional penalization does not work for most objective functions. A new penalization method, material penalization, is presented that does suppress intermediate densities in the transient thermal mechanical domain. Each element is given its own unique set of penalization parameters which are optimized to maximize the objective function < for a minimization problem. By reusing sensitivity information from the density variables, the additional computational cost is limited.)uuid:6d3efb71d5834a268ae9c7febc3eef73Dhttp://resolver.tudelft.nl/uuid:6d3efb71d5834a268ae9c7febc3eef73gOverhang Angle Control and Optimal Part Orientation in Topology Optimization for Additive Manufacturingvan de Ven, Emiel (Student TU Delft); Driessen, Anton (Student TU Delft); van Keulen, A. (TU Delft Structural Optimization and Mechanics); Langelaar, M. (TU Delft Structural Optimization and Mechanics)UTopology Optimization; Additive Manufacturing; Overhang constraints; Part orientation)uuid:a869dbe402804443afb7a3a386e3824bDhttp://resolver.tudelft.nl/uuid:a869dbe402804443afb7a3a386e3824b1Topology Optimisation Including Buckling AnalysisVan den Boom, S.J.Buckling is a failure mode of a structure caused by stiffness loss of compressed material. It arises primarily in slender structures, for which the bending stiffness is much lower than the axial stiffness. Slender, buckling sensitive structures occur especially in optimised designs, where an excellent strengthtoweight ratio is required. For this reason, buckling analysis of optimised designs is very important. However, buckling analysis is nowadays only performed in the postprocessing phase, after the optimisation is completed. Inclusion of a buckling constraint in topology optimisation should lead to a design where failure by buckling is already excluded. In the following postprocessing step, no major changes are needed on account of a buckling requirement, therefore allowing the final design to remain close to the optimal design. Ultimately this should lead to improved results. In literature, linear buckling analysis is included in topology optimisation on a couple of instances, albeit mostly in the role of an objective instead of as a constraint. In this report, an adjoint formulation for the sensitivities of the buckling load is found, resulting in much more efficient computation than other methods, such as finite differences. Furthermore, different practical aspects of inclusion of a buckling constraint are explored, with emphasis on the underlying physical problem. It is found that including a buckling constraint requires careful implementation, tailored to the specific optimisation problem at hand. An educated choice should be made on the admissibility of negative buckling loads. Allowing negative buckling loads leads to a nonconvex design space, complicating the search for the globally optimal design. Furthermore, the switching of modes should be considered. While mode switching can introduce a number of issues, preventing this switching limits the design freedom the optimiser has to reach an optimal design. Even more importantly, the point is raised that a linear buckling analysis does not give any information on the postbuckling behaviour of the structure. The stability of the buckling load greatly influences the sensitivity of the structure to imperfections. For practical implementations, an optimal design that is extremely sensitive to imperfections is worthless. Therefore, ideally, an assessment is done on the stability of the structure, during optimisation, in order to enforce stable post buckling behaviour. However, current techniques for postbuckling analysis are elaborate and timeconsuming in implementation and use. A method for rapid determination of the stability is required. Such a method for rapid estimation of the buckling load is found in the use of linear buckling analysis for structures that are perturbed with the mode shape of the perfect structure. This method is tested on very simple test structures and is found to be very promising for implementation in topology optimisation, because for a large part it can reuse code that is already available in the original formulation.topology optimization; bucklingPrecision and Microsystem)uuid:d51d2520eb35433e8637e331ba94987dDhttp://resolver.tudelft.nl/uuid:d51d2520eb35433e8637e331ba94987d?Topology Optimization including Inequality Buoyanc< y ConstraintsUPicelli, R.; Van Dijk, R.; Vicente, W.M.; Pavanello, R.; Langelaar, M.; Van Keuen, A.This paper presents an evolutionary topology optimization method for applications in design of completely submerged buoyant devices with designdependent fluid pressure loading. This type of structures aid rig installations and pipeline transportation in all water depths in offshore structural engineering. The proposed optimization method seeks the buoy design that presents higher stiffness, less material and a prescribed buoyancy effect. A hydrostatic fluid is used to simulate the underwater pressure and the polymer buoyancy module is considered linearly elastic. Both domains are solved with the finite element method. From the initial design domain, solid elements with low strain energy are iteratively removed until a certain prescribed volume fraction. The studied case consists in a buoy for supporting subsea oil pipelines, in which the inner diameter is constant and the outer shape and interior holes are defined by the optimization algorithm. A new buoyancy constraint is introduced in order to guarantee a satisfactory buoyancy effect.Ytopology optimization; BESO method; buoyancy; buoyant structures; subsea buoyancy modulesCIMNE)uuid:64200c38704d426fa423d0dd6f543213Dhttp://resolver.tudelft.nl/uuid:64200c38704d426fa423d0dd6f543213NIncorporating AMspecific Manufacturing Constraints into Topology Optimization
Serphos, M.R.JDesigns to be manufactured by Additive Manufacturing (AM) are subject to geometrical restrictions which are necessary to guarantee successful production. This makes it necessary to modify the obtained topology optimized design such that it is manufacturable. By doing this the optimality of the structure can be reduced. To achieve a manufacturable design directly from the topology optimization requires the incorporation of such a geometrical restriction directly into the optimization process. This research has been carried out to develop a method to do so. The manufacturing constraint being implemented is that a structure should be selfsupporting. For this to be the case overhanging features in the design must be at an angle of at least 45 degrees with respect to the base plate. Three approaches have been formulated and investigated: (1)a multiple objective, (2)global constraint and (3)a density filter. A global measure has been formulated for the multiple objective and the global constraint and a filtering scheme for the density filter. The three approaches have been implemented into a 2D optimization code written in MATLAB. Three predictable reference models have been used to test the suitability of each method. The results show that the multiple objective and the global constraint remain potential candidates but further investigation is needed to determine proper parameter values. The topologies obtained with these approaches were modified to partially meet the manufacturing constraint but remained with overhanging features. The filtering method produced topologies that had no overhanging features. The design was a compromise between slight alterations and the introduction of support structures. This approach however showed instabilities that are directly linked to the proposed filtering scheme. True convergence was not achieved with any of the approaches. The filtering approach provides a proof of concept for the inclusion of the 45 degree overhang restriction but further development is needed. The other two approaches are also potential candidates for inclusion of the restriction.topology optimization
20141112)uuid:afcb020f3d5e48d3b1a2a7ed12ccb594Dhttp://resolver.tudelft.nl/uuid:afcb020f3d5e48d3b1a2a7ed12ccb594qDirect gradient projection method with transformation of variables technique for structural topology optimization2Chang, C.; Borgart, A.; Chen, A.; Hendriks, M.A.N.VThis paper proposes an efficient and reliable topology optimization method that can obtain a black and white solution with a low objective function value within a few tens of iterations. First of all, a transformation< of variables technique is adopted to eliminate the constraints on the design variables. After that, the optimization problem is considered as aiming at the minimum compliance in the space of design variables which is supposed to be solved by iterative method. Based on the idea of the original gradient projection method, the direct gradient projection method (DGP) is proposed. By projecting the negative gradient of objective function directly onto the hypersurface of the constraint, the most promising search direction from the current position is obtained in the vector space spanned by the gradients of objective and constraint functions. In order to get a balance between efficiency and reliability, the step size is constrained in a rational range via a scheme for step size modification. Moreover, a grey elements suppression technique is proposed to lead the optimization to a black and white solution at the end of the process. Finally, the performance of the proposed method is demonstrated by three numerical examples including both 2D and 3D problems in comparison with the typical SIMP method using the optimality criteria algorithm.direct gradient projection method (DGP); structural topology optimization; transformation of variables technique; efficiency and reliability
20140601%Architectural Engineering +Technology)uuid:081e3d0e173b4a36b8d6c29c70eb7ae3Dhttp://resolver.tudelft.nl/uuid:081e3d0e173b4a36b8d6c29c70eb7ae3>Statically Balanced Compliant Mechanisms: Theory and SynthesisGallego Snchez, J.A.8Herder, J.L. (promotor); Van der Helm, F.C.T. (promotor)energyfree systems; static balancing; continuous equilibrium; zero stiffness; compliant mechanisms; flexible mechanisms; topology optimization; design of mechanismsBioMechanical Engineering)uuid:63b0662087534db7ab6bf36f9636bd69Dhttp://resolver.tudelft.nl/uuid:63b0662087534db7ab6bf36f9636bd699Performance Driven Design and Design Information Exchange/Mostafavi, S.; Morales Beltran, M.; Biloria, N.This paper presents a performance driven computational design methodology through introducing a case on parametric structural design. The paper describes the process of design technology development and frames a design methodology through which engineering, in this case structural aspects of architectural design could become more understandable, traceable and implementable by designers for dynamic and valid performance measurements and estimations. The research further embeds and customizes the process of topology optimization for specific design problems, in this case applied to the design of truss structures, for testing how the discretized results of Finite Elements Analysis in topology optimization can become the inputs for designing optimal trussed beams or cantilevers alternatives. The procedures of design information exchange between generative, simulative and evaluative modules for approaching the abovementioned engineering and design deliverables are developed and discussed in this paper.jperformance driven design; design information; design technology; topology optimization; parametric design)uuid:c728771bbcc04b4eb2cc8bea594db52dDhttp://resolver.tudelft.nl/uuid:c728771bbcc04b4eb2cc8bea594db52dPerformance Driven Design and Design Information Exchange: Establishing a computational design methodology for parametric and performancedriven design of structures via topology optimization for rough structurally informed design models3Mostafavi, S.; Morales Beltran, M.G.; Biloria, N.M.This paper presents a performance driven computational design methodology through introducing a case on parametric structural design. The paper describes the process of design technology development and frames a design methodology through which engineering, in this case structural aspects of architectural design could become more understandable, traceable and implementable by designers for dynamic and valid performance measurements and estimations. The research further embeds and customizes the process of topology optimization for specific design problems, in this cas< e applied to the design of truss structures, for testing how the discretized results of Finite Elements Analysis in topology optimization can become the inputs for designing optimal trussed beams or cantilevers alternatives. The procedures of design information exchange between generative, simulative and evaluative modules for approaching the above mentioned engineering and design deliverables are developed and discussed in this paper.PeCAADe (Education and research in Computer Aided Architectural Design in Europe))uuid:18461370a51344489adffbbaeaa572fdDhttp://resolver.tudelft.nl/uuid:18461370a51344489adffbbaeaa572fddTopology optimization of the compliant underactuated finger with the focus on outofplane stiffness
Goemans, V.Y.For largedisplacement mechanisms, such as underactuated fingers, the outofplane stiffness can pose problems, especially as it tends to vary over the inplane range of motion. In this paper a method is presented to design compliant underactuated fingers using topology optimization with a focus on obtaining a desired outofplane stiffness profile. Load path representation is used in combination with a nondominated sorting genetic algorithm. Aside from the thickness of beam elements, the curve of a beam element is also employed as design variable. A set of objective functions is used to evaluate the behavior of the outofplane stiffness over the range of motion. The resulting Pareto solutions provide insight into the tradeoff between the different objective functions on contact force and outofplane stiffness and also show the capability of this method to design compliant underactuated fingers. Using objective functions on outofplane stiffness results in solutions with a higher outofplane stiffness than when these objective functions were not used, while the solutions decrease little in performance in terms of contact force. The resulting shape of the outofplane stiffness over the inplane range of motion is shown to vary per solution. It is also shown that using curved beam elements can have a positive effect on the outofplane stiffness. Experiments on an underactuated finger prototype verified the simulation results.jtopology optimization; compliance; underactuated; finger; outofplane stiffness; load path representationBMD)uuid:4d9aa8136d514a0183f8bb8ed6bcc274Dhttp://resolver.tudelft.nl/uuid:4d9aa8136d514a0183f8bb8ed6bcc274lPushing the Boundaries: Levelset Methods and Geometrical Nonlinearities in Structural Topology OptimizationVan Dijk, N.P.This thesis aims at understanding and improving topology optimization techniques focusing on densitybased levelset methods and geometrical nonlinearities. Central in this work are the numerical modeling of the mechanical response of a design and the consistency of the optimization process itself. Concerning the first topic, we investigate different means to improve the robustness of densitybased numerical models including geometrical nonlinearities. The conventional approach (scaling the local material properties) can result in convergence problems due to excessive deformation in lowstiffness finite elements. To avoid excessive deformation, we combine the element connectivity parameterization method (adapting the connectivity between finite elements) with levelsetbased topology optimization. Furthermore, we achieve greater robustness of analysis method using a second and improved approach called element deformation scaling. This approach eliminates the need for solving internal equilibrium equations (needed for the element connectivity parameterization method) via an explicit relation between the local internal and global external displacement field. The second focus of this thesis is on the optimization process of levelsetbased topology optimization, and in particular its numerical consistency. We observe that signeddistance reinitialization of the levelset function affects the shape of a design in the optimization process. To minimize this effect, we propose a discrete levelset method that is based on an approximate H< eaviside function and focusing on the implementation. Furthermore, we also propose a levelsetbased topology optimization method using an exact Heaviside function and mathematical programming that effectively eliminates the need for reinitialization. We demonstrate that our densitybased levelset method is closely related to conventional densitybased topology optimization methods, while offering the advantage of more control over the geometrical complexity. On the other hand, we confirm that the dependence of the final result on the initial design which remains one of the big challenges for levelsetbased topology optimization. The potential of the proposed levelset method is shown by applying it on problems with stress constraints and geometrical nonlinearities and performing manufacturing tolerant topology optimization. Finally, this thesis offers a review of levelset methods for structural topology optimization to identify and discuss the different approaches that are available in literature. We can distinguish between levelset methods by examination of their design parameterization, sensitivities, update procedures and regularization techniques. A levelsetbased design parameterization offers the advantage of a crisp distinction between subdomains. For this reason, XFEM approaches and conforming discretizations are an interesting option to retain the crisp nature of the levelsetbased description of the design. Many levelset methods are combined with densitybased numerical models and are, therefore, closely related to conventional densitybased topology optimization methods. In particular, recently proposed projection methods have much in common with a levelsetbased design description. The results of levelsetbased TO methods often rely heavily on regularization techniques that introduce inconsistencies in the optimization process. Numerical consistency does not necessarily lead to the best search direction, but is essential to find a KarushKuhnTucker point of the discretized optimization problem.Ctopology optimization; levelset method; geometrical nonlinearities)uuid:1bd52cfcab2a404fbe98a6b71508f617Dhttp://resolver.tudelft.nl/uuid:1bd52cfcab2a404fbe98a6b71508f617Design and fabrication of topologically optimized structures; an integral approach, a close coupling form generation and fabricationFeringa, J.; Sondergaard, A.Integral structural optimization and fabrication seeks the synthesis of two original approaches; that of topological optimization (TO) and robotic hotwire cutting (HWC) (Mcgee 2011). TO allows for the reduction of up to 70% of the volume of concrete to support a given structure (Sondergaard & Dombernowsky 2011). A strength of the method is that it allows to come up with structural designs that lie beyond the grasp of traditional means of design. A design space is a discretized volume, delimiting where the optimization will take place. The number of cells used to discretize the design space thus sets the resolution of the TO. While the approach of the application of TO as a constitutive design tool centers on structural aspects in the design phase (Xie 2010), the outcome of this process are structures that cannot be realized within a conventional budget. As such the ensuing design is optimal in a narrow sense; whilst optimal structurally though, construction can be prove to be prohibitively expensive.Stopology optimization; robotics; hotwire cutting; EPS formwork; concrete structureseCAADeArchitecture)uuid:8fc929255796403b8ac20a63002d77bcDhttp://resolver.tudelft.nl/uuid:8fc929255796403b8ac20a63002d77bcKTopology Optimization For Localizing Design Problems: An Explorative ReviewReichard, C.A.Topology optimization is a valuable tool that can assist engineers in the design of many complex problems. However optimization techniques often have difficulties dealing with problems that have a strong tendency to localize in the global design domain forming a sparse design. Typically an extremely fine mesh is needed to capture these results, with high computational costs. Examples < are seen in spanning of large bridges, reinforcements of thin plates, and the branching effect of a heat conduction problem. The aim of this explorative review is to identify different possibilities to improve the computational efficiency. Next to reviewing current techniques, also two novel ideas were developed and evaluated. The first idea is inspired by techniques present in fields such as computer graphics. In this field 3D objects used in animation are represented by skeleton models to reduce the complexity of the problem. Similar techniques are investigated to determine if such an approach can be used within topology optimization to develop an optimum structure. The second idea employs an adaptive substructuring technique in a less traditional manner. The computational domain is split in a part that is changing and one that is static during the optimization process. The overall goal of both proposed approaches is to improve the solution process by reducing the number of variables needed to be solved to obtain the response of the design. From these investigations and research many ideas are presented which bring benefit to the sparse problem in optimization. The idea of skeleton modeling is a potential method but has several issues in developing the model and obtaining the temperature response. The substructuring approach is a promising development offering significant improvements with up to approximately 67% time savings in the finite elements were shown for a design problem using 1% of the orignal volume.Jtopology optimization; heat conduction; substructuring; skeleton modeling)uuid:6dd0caf03128420093a5104ebbbc135fDhttp://resolver.tudelft.nl/uuid:6dd0caf03128420093a5104ebbbc135fYFeasibility study on fiber reinforced polymer cylindrical truss bridges for heavy trafficChlosta, M.cBijlaard, F.S.K. (mentor); Kolstein, M.H. (mentor); De Boer, A. (mentor); Hendriks, M.A.N. (mentor)Considering the recent increase in the use of fiber reinforced polymers in the civil engineering industry in general and in the bridge engineering industry in particular, as well as the recently more and more applied cylindrical truss bridge type, this research focuses on the question whether it is possible to combine fiber reinforced polymers as standalone structural material and this bridge type to construct a bridge suitable for heavy traffic as well as bicycle and pedestrian traffic. This research combines an extensive literature study on the use of fiber reinforced polymers for bridge engineering with a theoretical feasibility and designstudy on fiber reinforced polymer cylindrical truss bridges for heavy traffic. During the design study the spatial needs of all bridge users were defined to obtain an initial shape of the bridge. This shape was then optimized in several steps using finiteelementmodeling and analysis, yielding a final shape of the bridge. The behavior of this structure under design loads was then extensively investigated, again using finite element analysis, showing that the bridge could very well meet the selfderived deflection limit for fiber reinforced polymers at relatively low stress levels. Since fiber reinforced materials are a very diverse field of material, with hundreds of different compositions being available, the first result of this study was the choice of a suitable composite for further analysis. For this bridge design very high fiber content (>60%) carbon/epoxy composite was used. The main reason for this choice was the high modulus and strength of the carbon fibers and the high durability and strength of the epoxy resin. A major reason of the slow implementation of fiber reinforced polymers in the bridge engineering industry are the worries concerning the lack of fire safety of the material. The literature study of this research showed however that it is possible to construct a heavy traffic fullFRP truss bridge, while complying with the known fire safety standards. The virgin FRP material can be adapted by several fireprotection measures; it turned out that a combination of intumescent gelcoat< ing and low volume phosphorous filler systems works best in increasing the fire resistance and thereby providing a fire resistance class of R30 for hydrocarbon fire curve loading. The initial shape of the bridge was optimized in three stages: first several different truss topologies, which were derived with a parametric geometric model, were analyzed and compared using finite element analysis software, yielding the square truss with one diagonal as most efficient topology. In the next steps several grid sizes of this truss as well as several cross section dimensions were compared, again using finite element analysis software. An optimum was found between minimum material usage and minimum deflection, which reduced the material usage of the main load bearing elliptical truss by about 40% compared to the initial variant. The optimized structure was then fitted with the inner bridge deck supporting trusses as well as the cantilever trusses. The elliptical truss bridge performed very well considering the maximum deflections and stresses under Eurocode design loads and load combinations that were derived in finite element modeling software. When comparing the fullFRP bridge design with similar, existing steel structures, the maximum deformations and stresses were considerably lower for the fullFRP bridge while only weighing about 60% of the steel structure. This research showed that the new cylindrical truss bridge type is not only an aesthetically appealing structure but also performs structurally very well when combined with fiber reinforced polymer as structural material. It turned out that fiber reinforced polymers can be used as standalone structural material for medium span heavy traffic bridges. Next to that, this research clarified that there is no legitimate structural reason for the fact that fiber reinforced polymers are used relatively scarcely in the civil engineering and bridge engineering industry compared to traditional building materials such as steel and concrete. Since this research is one of the first researches of its kind, using FRP as standalone structural material for a relatively new and complex bridge type, more research is needed in the field of high order connections for fiber reinforced polymer circular hollow sections. Next to that the possibility of the use of differently sized and shaped cross sections for the truss members should be investigated.fiber reinforced polymers; plastics; FRP; civil engineering; bridge engineering; structural engineering; structural design; bridge design; stiffness driven design; cylindrical truss; elliptical truss; tubular truss; spatial truss; truss topology optimization; grid size optimization; space efficiency; heavy traffic road bridge; truss topology; mechanical properties of FRP materials; fire safety; fire resistance; steel viaduct comparison; FEA; FEM; finite element modeling; finite element analysis; CFRP; carbon; epoxy
20120724)uuid:999bb01078764ea785f38bf75ab32071Dhttp://resolver.tudelft.nl/uuid:999bb01078764ea785f38bf75ab32071^A levelset based topology optimization using the element connectivity parameterization method9Van Dijk, N.P.; Yoon, G.H.; Van Keulen, F.; Langelaar, M.This contribution presents a novel and versatile approach to geometrically nonlinear topology optimization by combining the levelset method with the element connectivity parameterization method or ECP. The combined advantages of both methods open up the possibility to treat a wide range of optimization problems involving complex physical and/or geometrical nonlinearities in a general and elegant manner. The levelset method features shape optimization on a fixed mesh, leading to intrinsically blackandwhite designs. This approach allows a clear description of location and orientation of the interface, whereas topological changes can still be handled easily. A popular concept used in conventional levelset methods is to map the levelset function to volumefraction design variables for every element of a finite element mesh. The resulting element density variables are then us< ed to scale the Young s modulus in each element using the Ersatz material approach. In this work we employ a modified material interpolation method, in which the element density variables, based on a perelement integration of a regularized Heaviside operator applied to the levelset function, are used as element connectivity design variables. The resulting crisp boundary topology optimization method exploits the advantages of ECP in the field of complex nonlinearities and eliminates the need for penalization by the implicit levelset description of the design.wtopology optimization; levelset method; element connectivity parameterization method (ECP); geometrical nonlinearities)uuid:2fc873ce037e4b1c8450c5604d00421eDhttp://resolver.tudelft.nl/uuid:2fc873ce037e4b1c8450c5604d00421eDWind load modeling for topology optimization of continuum structures2Zakhama, R.; Abdalla, M.M.; Grdal, Z.; Smaoui, H.Topology optimization of two and three dimensional structures subject to dead and wind loading is considered. The wind loading is introduced into the formulation by using standard expressions for the drag force, and a strategy is devised so that wind pressure is ignored where there is no surface obstructing the wind. A minimum compliance design formulation is constructed subject to a volume constraint using the Solid Isotropic Material with Penalization model. The optimization problem is solved using the Method of Moving Asymptotes, modified by including a line search and by changing the formula for the update of asymptotes. To obtain black/white design, intermediate density values, which are used as design variables, are controlled by imposing an explicit constraint. Numerical examples of a windmill structure demonstrate that the proposed formulation rationally incorporates the effect of wind loading into the topology optimization problem as illustrated by void appearing in the optimal structure.bTopology optimization; Continuum structures; Design dependent loads; Wind loads; Moving asymptotesSpringer Verlag)Aerospace Structures & Design Methodology)uuid:21b74bdaea2a48d786d3304c6045cd51Dhttp://resolver.tudelft.nl/uuid:21b74bdaea2a48d786d3304c6045cd51\Design optimization of shape memory alloy active structures using the Rphase transformationLangelaar, M.; Van Keulen, F.This article illustrates the opportunities that combining computational modeling and systematic design optimization techniques offer to facilitate the design process of shape memory alloy (SMA) structures. Focus is on shape memory behavior due to the Rphase transformation in NiTi, for which a dedicated constitutive model is formulated. In this paper, efficient topology and shape optimization procedures for the design of SMA devices are described. In order to achieve fast convergence to optimized designs, sensitivity information is computed to allow the use of gradientbased optimization algorithms. The effectiveness of the various optimization procedures is illustrated by numerical examples, including the design of a miniature SMA gripper and a steerable SMA active catheter. It is shown that design optimization enables designers of SMA structures to systematically enhance the performance of SMA devices for a variety of applications.`shape memoray alloys; NiTi; Rphase; topology optimization; sensivity analysis; active catheterSPIE4Department of Precision and Microsystems Engineering)uuid:dc06f01fb5a64bfbb0fbdc6f5d880055Dhttp://resolver.tudelft.nl/uuid:dc06f01fb5a64bfbb0fbdc6f5d8800554Design optimization of shape memory alloy structures
Langelaar, M.van Keulen, A. (promotor)This thesis explores the possibilities of design optimization techniques for designing shape memory alloy structures. Shape memory alloys are materials which, after deformation, can recover their initial shape when heated. This effect can be used for actuation. Emerging applications for shape memory alloys are e.g. miniaturized medical instruments with embedded actuation, as well as microsystem components. However, designing effective shape memory alloy structures <is a challenging task, due to the complex material behavior and the close relationship between geometry, electrical, thermal and mechanical properties of the structure. In this thesis, various approaches are developed to combine optimization algorithms with computational modeling of shape memory alloy structures. The focus is on the shape memory behavior of NiTi alloys that exhibit the Rphase/austenite transformation. Dedicated computationally efficient constitutive models are formulated to capture this behavior and predict the performance of designs. The considered optimization approaches include deterministic shape optimization, shape optimization under boundedbutunknown uncertainty, gradientbased shape optimization and topology optimization. Together they provide a collection of efficient and systematic techniques to generate wellperforming designs. Their applicability and effectiveness is evaluated by application to design studies of realistic complexity, involving the design of miniature grippers and steerable catheters. The developed design optimization techniques are expected to be of great use for the design of future instruments and devices that utilize shape memory alloy actuation.Initi; shape optimization; topology optimization; rphase; active catheterMechanical Maritime and Materials Engineering)uuid:cf5c2f1166e94da69127ab3662a5c7acDhttp://resolver.tudelft.nl/uuid:cf5c2f1166e94da69127ab3662a5c7ac$Design of microfluidic bioreactorsOkkels, F.; Bruus, H.We address the design of optimal reactors for supporting biological cultures using the method of topology optimization. For some years this method have been used to design various optimal microfluidic devices [1, 2, 3, 4]. We apply this method to distribute optimally biologic cultures within a flow of nutrition. From this optimized distribution alone the metabolic rate in the reactor increase by close to a factor 20.2microfluidics; bioreactors; topology optimization)uuid:01207185bd814868973b139921dee869Dhttp://resolver.tudelft.nl/uuid:01207185bd814868973b139921dee869UComputation of topological sensitivities in fluid dynamics: Cost function versatility%Othmer, C.; Kaminski, T.; Giering, R.Topology optimization of fluid dynamical systems is still in its infancy, with its first academic realizations dating back to as late as three years ago. In this paper, we present two approaches to fluid dynamic topology optimization that are based on potential flows and adjoint states, respectively. Special emphasis is paid to the computation of topological sensitivities with discrete adjoints and its versatility with respect to changes of the cost function: After providing the proof of concept of a discrete adjointbased methodology for the optimization of dissipated power, we compute sensitivities with respect to equal mass flow through different outlets, flow uniformity and also angular momentum of the flow in the outlet plane.FCFD; topology optimization; adjoint methods; automatic differentiation
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Root Entry F@SummaryInformation( F<Workbook F"DocumentSummaryInformation8 F
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!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[