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Title:Elastic properties of architectured cellular materials and biological materials (equine hoof wall)
Author(s):Shiang, Cheng-Shen (Andrew)
Advisor(s):Jasiuk, Iwona M
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):3D printing
Triply periodic minimal surface
Mechanical testing
Architectured materials
Equine hoof wall
Linear-elastic modeling
Abstract:This thesis addresses two main topics: the mechanical behavior of cellular materials based on triply periodic minimal surfaces (TPMS) and the analytical modeling of the elastic response of a horse hoof wall. TPMS structures have smooth surfaces with no sharp corners making them promising candidates for superior mechanical properties materials. The horse hooves are highly impact-resistant biological structures. The goal of studying the TPMS and horse hoof is to understand how the architectured structures provide mechanical benefits. In the first part of this thesis, the TPMS-based Gyroid-type cellular materials with varying porosities are investigated experimentally under compression. Specimens, few centimeters in size, were fabricated using selective laser sintering (SLS) with a PA2200 polymer. The elastic compressive uniaxial modulus, compressive strength, and energy absorption of Gyroid structures are compared with those of the IWP-, Neovius-, and Primitive-structures from a previous study. Gyroid structures have competitive mechanical properties compared to other TPMS-based structures. Finite element simulations involving the Arruda-Boyce finite-deformation elasto-viscoplastic model show good agreement with experimental data. In the second study, the TPMS-based cellular microlattices with Neovius architecture are investigated at a micron scale under compression. Specimens, few hundred microns in size, were fabricated with the 3D printer Nanoscribe using a proprietary polymer named IP-S. The main deformation mechanisms in the Neovius microlattices are buckling and plastic yielding, while the brittle fracture is not observed. The Neovius microlattice exhibits high compressive uniaxial elastic modulus, energy absorption, and strength thanks to the absence of sharp corners in the geometry. These properties are further enhanced by the addition of ceramic (alumina) coating. The third study on TPMS lattice structures covers the bending of TPMS-structured beams with different beam heights and cell sizes. One group has constant specimen dimensions with varying unit cell sizes. The other group has fixed unit cell sizes but different overall specimen dimensions with beam heights varying. Both groups were fabricated using the SLS technique and PA2200 material, with dimensions being in centimeters. Under four-point bending, the samples with constant specimen dimensions exhibited behavior in line with a classical elasticity theory. In contrast, the models with fixed unit cell sizes exhibited a softening behavior as the size decreased. The fourth study covers the analytical modeling of elastic properties of a horse hoof wall and comparison with existing experimental data. The hoof wall is represented as a composite material with a hierarchical structure, with length scales ranging from nanoscale intermediate filaments to the macro-scale hoof wall with mesoscale tubules within. The models employed are Voigt and Reuss bounds, Composite Cylinders model, Halpin-Tsai model, Mori Tanaka theory, and a classical laminate theory. The results agree at the mesoscale and sub-mesoscale with the experimental data found in the literature, while the experimental data is lacking for other scales. The final chapter summarizes two highly specialized 3D printers and provides guidance on their usage, namely the Nanoscribe printer capable of printing materials and structures few to few hundred microns in dimensions and the Bioplotter designed to print biopolymers micron to centimeters in dimensions.
Issue Date:2021-04-29
Rights Information:Copyright 2021 Cheng-Shen (Andrew) Shiang
Date Available in IDEALS:2021-09-17
Date Deposited:2021-05

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