Print Email Facebook Twitter Property-based functional gradients for biomimetic composites Title Property-based functional gradients for biomimetic composites Author Veeger, Robin (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Biomaterials & Tissue Biomechanics) Contributor Mirzaali, Mohammad J. (mentor) Zadpoor, A.A. (mentor) Ruffoni, Davide (mentor) Zadpoor, A.A. (graduation committee) Abrahami, S.T. (graduation committee) Mirzaali Mazandarani, M. (graduation committee) Cruz Saldivar, M. (graduation committee) Degree granting institution Delft University of Technology Programme Biomedical Engineering Date 2021-11-26 Abstract Functional gradients in hard-soft interfaces are abundant in nature, and we often mimic them to create strong and tough composites. A powerful tool for the designs and fabrication of biomimetic composites is voxel-based multi-material 3D printing. Earlier researches mainly focused on using this technique in the creation of gradients based on morphology. While this is a great way to create a gradient, the outcome material properties are often unknown. In this research, we attempted to create a gradient based on the desired outcome material properties rather than morphology. We created a linear gradient in density using a voxel-based 3D printing technique and tested it through nanoindentation. Furthermore, we created a Finite Element Model based on this sample. Out of the nanoindentation and Finite Element Model results, we extracted the b-value for a power-law function in the form of E(x)= E_h 〖ρ(x)〗^b+E_s. With the inverse of this power-law function, we designed three different gradients based on the desired material properties: a linear, stepwise, and sigmoid gradient. Nanoindentation experiments and Finite Element analyses showed that we achieved the desired outcome in material properties with our newly created approach of designing gradients. However, the nanoindentation experiments showed that using a machine suitable for the wide range of Young’s moduli present in these kinds of composites is crucial. To display the possible applications of our new approach, we designed a knee model with graded ligaments and tested it with a tensile test and digital image correlation. Results of these tests showed an energy before failure that was twice as high as its non-graded counterpart. Furthermore, with the introduction of the gradient, we achieved to change to loading condition on the ligaments. Overall, our results show that our new approach can create gradients based on material properties rather than morphology and opens many new doors in creating biomimetic composites. Subject Functional gradientsProperty-basedBiomimeticsCompositeshard-soft interfacesVoxel-based additive manufacturing3D PrintingFinite Element AnalysisFinite Element MethodBitmapMulti-Material Additive ManufacturingGradient by designNanoindentation To reference this document use: http://resolver.tudelft.nl/uuid:8a336e15-8ba4-4ed8-9f59-15ae9b01fe71 Embargo date 2023-11-26 Part of collection Student theses Document type master thesis Rights © 2021 Robin Veeger Files PDF Master_thesis_Robin_Veege ... 302931.pdf 11.1 MB Close viewer /islandora/object/uuid%3A8a336e15-8ba4-4ed8-9f59-15ae9b01fe71/datastream/OBJ/view