This thesis investigates novel foaming materials for fused deposition modelling (FDM) which have been introduced in 2019. The materials are able to foam by the addition of foaming agents. Foaming materials for FDM printing can be advantageous since they can create lightweight models, and have good impact strength and toughness in relation to their weight (Nofar et al, 2022). The goals of this thesis are to: research the existing knowledge about foaming materials for FDM printing, characterize the different printing parameters that influence the amount of foaming and propose an application for foaming materials for FDM printing. The investigated materials are foaming PLA, ASA, and TPU.
The first goal is reached by conducting a literature review. First, the material properties of foaming materials outside the scope of FDM printing are investigated to better understand the advantages for foaming materials for FDM as well. Second, printing parameters are investigated to understand how these affect final printed products. Third, the available literature for the foaming filaments for FDM printing is investigated. An overview of the material properties in tension is made for the foaming filaments. This shows that most material properties are known for the foaming PLA.
The second goal is reached by conducting three experiments, which investigate the influence of nozzle temperature, fan, printing speed and flow rate. From these experiments it is concluded that the nozzle temperature, printing speed and flow rate influence the expansion of the material, depending on the desired outcome. The fan speed only influences the expansion of the foaming TPU. With the results of these experiments, an overview is made of the influence of the printing parameters on the expansion using the three-link chain model (Doubrovski et al, 2011).
The third goal is reached by conducting a compression experiment in which the foaming PLA is compared with expanded polystyrene (EPS). The results from this experiment and the printing parameters are applied within a motorcycle helmet as demonstrator. This demonstrator shows that the foaming materials for FDM printing could be an interesting area for further research.
This thesis provides a starting point for further research into the influence of printing parameters for foaming materials, as well as the material properties of the foaming filaments. It is recommended to further investigate the influence of more printing parameters on foaming, such as bed temperature, nozzle geometry and type of printer. Second, it is recommended to further investigate the material properties of foaming TPU and ASA as well, since only PLA was tested in the compression experiment. Apart from this, the materials could also be further investigated for tension. Lastly, the proposed foaming PLA sample for the motorcycle helmet could be further investigated for higher strain rates, to confirm the feasibility for the use of motorcycle helmets.
Overall, this thesis investigates the printing parameters for foaming materials which are used to create samples with specific densities for a compression experiment. With the found printing parameters and results from the compression test, a helmet demonstrator is create

The widespread proliferation of cellular lattices in engineering design has entailed a revolution in the design of lightweight and multifunctional structures. Furthermore, the development of auxetic metamaterials has led to applications in fields ranging from biomedical to civil engineering. However, cellular lattices suffer from the development of localized concentrations of strains during deformation, which lead to sub-optimal mechanical performance. Furthermore, the mechanical properties of cellular lattices are dependent on their macro-scale geometries, limiting their design space. Thus, we seek to both enhance the mechanical properties of lattices by ameliorating strain concentrations and expand the design space of cellular lattices.

In attempting to do so, we can turn to nature. The bio-inspired design motif of the hierarchical arrangement of composite materials has lead to exceptional mechanical characteristics in natural materials. Moreover, morphogenetic processes such as bone remodelling play a vital role in the structural development of natural materials and their hierarchical material arrangement. Motivated by these concepts, we developed an algorithm that optimised the hierarchical material arrangement of hard and soft voxels in an auxetic and non-auxetic unit cell. Our algorithm does so based on a bone remodelling-like approach of strain energy optimisation, whereby elements are transitioned to a hard or soft material based on local strain energy.

Our finite element (FE) simulation results demonstrate the considerable expansion of the range of mechanical properties we can achieve simply by modifying material placement on a micron scale. We also observe clear mitigation of peak strain energies and more homogeneous distributions of strain energy density, which affirm the amelioration of strain concentrations. Furthermore, we were able to increase the stiffnesses of our unit cells without substantially affecting its Poisson’s ratio, disentangling previously interdependent mechanical properties. We further validated our FE simulations by additively manufacturing our optimised unit cells with state-of-the-art voxel-based printing. Both the mechanical properties predicted by our FE simulations and the strain distributions correlated well with digital image correlation recordings, validating our models. Our mechanical testing also revealed the considerable in- creases in ultimate tensile strength of our optimised designs, demonstrating the benefits of hierarchical material arrangement.

To conclude, we demonstrate the efficacy of strain energy-based material optimisation to improve the mechanical properties of unit cells and mitigate strain concentrations. The design paradigms of hierarchical arrangement of composite materials remarkably improved the material space of a unit cell without changing its macro-scale geometry. Findings from this study could enable the optimisation of existing cellular lattices and the development of novel unit cell designs with distinct intrinsic mechanical properties.

Venously printed contributes to the field of HCI and digital manufacturing by exploring the scope and possibilities for programmable and responsive fluidic interfaces, using multi-material 3D printing as a manufacturing technique. Novel meta-materials and computational composites have proven to open up new design paradigms and continue to expand the design space for HCI and material design with unprecedented I/O configurations and material experiences. By encoding the computational logic of dynamic and responsive behaviour into the material’s structure and properties, these materials allow shifting away from typical 2D (digital) interfaces towards embedded responsive 3D objects and materials without the need for external logical operators or controllers.

A novel concept within this field is fluidic interfaces, which utilise liquid flow as a medium to drive dynamic appearance triggered by mechanical deformation input such as pressure, twisting or bending. Within this research, multi-material 3D printing is explored as a manufacturing tool for such fluidic interfaces to allow for more complex 3D geometries, dynamic visual output and encoded computational logic. A set of demonstrators are developed with programmable dynamic appearance, showcasing the capabilities of this manufacturing workflow and the possibility of being tuned for specific material experiences or temporal form in interaction design.

To allow for the fabrication of these interfaces Venously printed presents a fabrication pipeline, including a computational design and simulation tool for designers to validate the responsive behaviour and iterate on their design before going into manufacturing. Additionally, a voxel-based support structure for 3D printing complex internal cavities is developed to provide better printing quality as opposed to available workflows whilst still being able to be removed from complex internal structures. Finally, a first step for the characterisation of the experiential qualities of fluidic interfaces has been performed via a set of interviews. This led to promising future applications and material experiences which can be explored in future work.

This graduation report aimed to improve the mechanical properties of a sustainable 3D print material made of microalgae, in order to create an macro-porous 3D structure with enhanced longevity and photosynthetic activity. This research builds upon the alginate based bio-ink from Balasubramanian et al (2021). Their material proposal lacked structural stability and print resolution, which made geometries of more than six layers impossible. Moreover, the bioprints were confined to a nutrient plate. These challenges formed the motivation for the research. The goal for the optimized bioprinting protocol was to make use of the advantages of additive manufacturing, by creating a macro-porous shape with increased surface ratio. The hypothesis was that the microalgae would have more access to light, air and nutrients which would increase oxygen release and carbon dioxide fixation. In a series of explorative studies, in close collaboration with nanobiologists, biomaterial designers and 3D printing experts, a direct ink writing approach was selected to construct the microalgae bioprints. Additional components were added to the alginate bio-ink formulation, which concluded in a material with improved print fidelity and resolution, so that more than 25 layers could be bioprinted. With the optimized protocol, the 3D printed construct could be crosslinked so that the print was stable enough to be handled. The microalgae immobilized in the ink formulation survived more than seven days in the 3D printed geometry. The photosynthetic performance of the material was observed, by building an incubator prototype with oxygen and carbon dioxide sensors. The sensors measured two different bioprints simultaneously, a macro-porous cube and a solid cube. The superiority of the photosynthetic ability of the porous geometry over the solid geometry could not be concluded, due to the limitations of the sensors and the prototype setup. Important insights were found for further research on the improvement of the test setup. The optimized microalgae bio-ink is a valuable material with sustainable benefits. The material can actively fight carbon dioxide pollution, is carbon neutral in production and is biodegradable. The technical optimization of the bio-ink in this study formed the first steps towards a functional living microalgae artefact.

The use of 3D printing technology in manufacturing environments has experienced rapid growth. Manufacturers have realised the potential of the technology. 3D printing enables the reduction of costs and lead-times of parts, components and tools used in production processes. Adoption of this technology is facing various challenges. A major challenge is the identification of suitable parts for Additive Manufacturing technology. Assessing a part’s suitability for 3D printing requires a substantial amount of knowledge of 3D printing technology. Within manufacturing and production environments, a limited group of people is trained to do understand the technology. It is expected that the frequency and quality of applications will increase the value that will be added by 3D printing. This development will be driven by the capability to identify new applications. The more stakeholders are educated in this field and understand the technology, the more opportunities will be identified. Given the above, this objective of this research project is to investigate how production line operators can be more actively involved in the initial stages of the 3D printing workflow. Through extensive literature and contextual research, the potential to enable production line operators to identify parts and problems in their section of the facility has been exposed. Various influential opportunities and challenges in their participation have been established. After a round of internal validation of the research insights, a strategic decision was made to focus design efforts on developing a digital platform. The objective of this platform is to enable operators to participate in the relevant steps of the 3D printing workflow. Through an iterative process, an Application Portal has been designed. This portal is a mobile application that supports production line operators in submitting new ideas. In addition to the above, the system offers the following functions:
1.Active collaboration between stakeholders
2.Exchange of project developments insights
3.Validation of application suitability A prototype is developed in Axure. This software is used to validate the concepts with a variety of manufacturing clients, operators and 3D print experts. The applicability of the concept has been validated for a majority of clients. These results illustrate that the solution offers significant value to achieve active participation. Additional design goals have been achieved to a great extent. The application portal provides operators with a tool to express their ideas. They can actively participate in innovation and take ownership of the applications they have identified themselves. Additionally, the platform offers Ultimaker and its manufacturing clients an opportunity to gather relevant data to work towards a future of automated part identification. Inevitably, the prototype has its limitations. However, this study represents a step forward in the acceleration towards accessible part identification by novice users in manufacturing environments.

This thesis covers the design, implementation, and manufacturing methodology of a custom mouthpiece for the automatic toothbrush in development by Dental Robotics. The results are a proof-of-concept digital processing pipeline, a functional prototype, an evaluation of custom mouthpiece efficacy relative to the standard mouthpiece, and a recommended manufacturing setup.

The graduation project is carried out as a collaboration between the Delft University of Technology and Ultimaker. Ultimaker B.V. is a 3D printer company located in Geldermalsen, The Netherlands. Users of 3D printers are presented with a multitude of action possibilities. However, these action possibilities are not yet translated into easy to understand controls that match user intentions. The goal of this project is to design a means for the user to match the intended outcome with the printed result. Eight design opportunities for intent-based 3D printing approaches are defined based on desk research and user experiments. The desk research focuses on the material extrusion process, the 3D printing workflow, user groups, market trends and intent facilitation techniques. The user experiments analyse the role of user intent in the 3D printing workflow. The eight defined design opportunities are: goal-oriented print preparation, reducing the knowledge threshold, component level control, promotion of 3D printing affordances, management of 3D printers, user education, intent communication and feedback. Ideation is applied to these design opportunities to create three concepts, of which the highest scoring concept is further developed. The proposed design is a software plugin for the Cura engine based on product configuration systems used in retail. The software architecture consists of six modules that work together to analyse the model geometry, retrieve requirements and wishes based on the communicated intent, recommend profile selections and user actions, validate the print preparation process and guide the user towards ideal printer configurations and process parameters. By using the 3MF file format, models are separated into several components, which can be configured individually by means of ‘component profiles’. Component profiles are developed by Ultimaker, companies and individual users to present a subset of print settings that facilitate an intended 3D printed result. A software plugin for Cura 3.3.1 is developed as a prototype for testing the designed intent-based 3D printing approach. Due to the scope of this research, testing is limited to component-level manipulations and control of goal-oriented settings. From the user test, it can be concluded that print preparation using component profiles significantly improves user guidance and the educative experience of print preparation. Especially beginners are more confident that their configuration leads to the desired part qualities. The objective plugin reduces the feeling of control, but even expert users show confidence in the final result. Within the plugin users can better voice their intentions through selecting component profiles. These profiles present meaningful feedback to users that both guides and educates them. Of course the realized plugin has its limitations: it does not use intent information that can be included in the supplied model files, nor does it offer all the designed guiding features. Even though these limitations exist, this study represents a step forward in the journey from process-driven to intent-based 3D printing.