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Zhai, X. (author), Chen, Falai (author), Wu, J. (author)Handling stress constraints is an important topic in topology optimization. In this paper, we introduce an interpretation of stresses as optimization variables, leading to an augmented Lagrangian formulation. This formulation takes two sets of optimization variables, i.e., an auxiliary stress variable per element, in addition to a density...journal article 2021
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van de Ven, E.A. (author), Maas, Robert (author), Ayas, C. (author), Langelaar, Matthijs (author), van Keulen, A. (author)It is attractive to combine topology optimization (TO) with additive manufacturing (AM), due to the design freedom provided by AM, and the increased performance that can be achieved with TO. One important aspect is to include the design rules associated with the process restrictions of AM to prevent the requirement of relatively large support...journal article 2020
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Xia, Y. (author), Langelaar, Matthijs (author), Hendriks, M.A.N. (author)Strut-and-Tie modelling (STM) is a well-known approach to design D-regions in reinforced concrete structures. Because the STM method is based on lower-bound analysis, finding a suitable truss-analogy model is the most important aspect to guarantee good structural and economic performance of a resulting design. Continuum topology optimization ...journal article 2020
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Delissen, A.A.T.M. (author), van Keulen, A. (author), Langelaar, Matthijs (author)In many engineering applications, the dynamic frequency response of systems is of high importance. In this paper, we focus on limiting the extreme values in frequency response functions, which occur at the eigenfrequencies of the system, better known as resonant peaks. Within an optimization, merely sampling the frequency range and limiting the...journal article 2020
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van den Boom, S.J. (author), Zhang, J. (author), van Keulen, A. (author), Aragon, A.M. (author)During design optimization, a smooth description of the geometry is important, especially for problems that are sensitive to the way interfaces are resolved, e.g., wave propagation or fluid-structure interaction. A level set description of the boundary, when combined with an enriched finite element formulation, offers a smoother description...journal article 2020
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Kumar, P. (author), Frouws, Jan (author), Langelaar, Matthijs (author)In various applications, design problems involving structures and compliant mechanisms experience fluidic pressure loads. During topology optimization of such design problems, these loads adapt their direction and location with the evolution of the design, which poses various challenges. A new density-based topology optimization approach...journal article 2020
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Delissen, A.A.T.M. (author), Laro, Dick (author), Kleijnen, Harry (author), van Keulen, A. (author), Langelaar, Matthijs (author)In the design process of high-precision motion stages, the dynamic behavior is of paramount importance. Manual design of such a stage is a time-consuming process, involving many iterations between engineers responsible for mechanics, dynamics and control. By using topology optimization in combination with additive manufacturing, post...conference paper 2020
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Xia, Y. (author), Wu, Yue (author), Hendriks, M.A.N. (author)In current optimization methods for free-form 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...journal article 2019
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Kumar, P. (author), Fanzio, P. (author), Sasso, L. (author), Langelaar, Matthijs (author)The concept and synthesis approach for planar Compliant Fluidic Control Structures (CFCSs), monolithic flexible continua with embedded functional pores, is presented in this manuscript. Such structures are envisioned to find application in biomedicine as tunable microfluidic devices for drug/nutrient delivery. The functional pores enlarge and...journal article 2019
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Langelaar, Matthijs (author)This paper presents a topology optimization approach that incorporates restrictions of multi-axis machining processes. A filter is defined in a density-based topology optimization setting, that transforms an input design field into a geometry that can be manufactured through machining. The formulation is developed for 5-axis processes, but...journal article 2019
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Groen, J.P. (author), Wu, J. (author), Sigmund, Ole (author)This paper concerns compliance minimization and projection of coated structures with orthotropic infill material in 2D. The purpose of the work is two-fold. First, we introduce an efficient homogenization-based approach to perform topology optimization of coated structures with orthotropic infill material. The design space is relaxed to allow...journal article 2019
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Langelaar, Matthijs (author)Purpose: 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 post-print machining requirements. Design/methodology/approach: An integrated topology optimization is proposed using two density...journal article 2019
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Wang, W. (author), Munro, D.P. (author), Wang, C.C. (author), van Keulen, A. (author), Wu, J. (author)The design of optimal structures and the planning of (additive manufacturing) fabrication sequences have been considered typically as two separate tasks that are performed consecutively. In the light of recent advances in robot-assisted (wire-arc) additive manufacturing which enable addition of material along curved surfaces, we present a...journal article 2019
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Koppen, S. (author), van der Kolk, M. (author), van Kempen, F.C.M. (author), de Vreugd, J (author), Langelaar, Matthijs (author)The stringent and conflicting requirements imposed on optomechanical instruments and the ever-increasing 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,...journal article 2018
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Liu, Jikai (author), Gaynor, Andrew T. (author), Chen, Shikui (author), Kang, Zhan (author), Suresh, Krishnan (author), Takezawa, Akihiro (author), Li, Lei (author), Kato, Junji (author), Tang, Jinyuan (author), Wang, C.C. (author), Cheng, Lin (author), Liang, Xuan (author), To, Albert. C. (author)Manufacturing-oriented 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 close-to-optimal and friendly-to-manufacture...journal article 2018
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Gupta, D.K. (author), Barink, Marco (author), Langelaar, Matthijs (author)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 non-uniform...journal article 2018
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Langelaar, Matthijs (author)Additive 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 powder-bed-based AM processes, the critical overhang angle of downward facing surfaces limits...journal article 2018
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van de Ven, E.A. (author), Maas, Robert (author), Ayas, C. (author), Langelaar, Matthijs (author), van Keulen, A. (author)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...journal article 2018
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Hakkaart, X.D.V. (author), Pronk, J.T. (author), van Maris, A.J.A. (author)Understanding microbial growth and metabolism is a key learning objective of microbiology and biotechnology courses, essential for understanding microbial ecology, microbial biotechnology and medical microbiology. Chemostat cultivation, a key research tool in microbial physiology that enables quantitative analysis of growth and metabolism under...journal article 2017
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Verbart, A. (author), Langelaar, Matthijs (author), van Keulen, A. (author)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 design-dependent set of constraints into an equivalent optimization problem with a fixed design-independent set of constraints. The next...journal article 2017