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Arya Amiri, PhD candidate
Mechanical Heterogeneity in Soft Biological Tissues: Intra- and Inter- Subject Variability
Abstract: Mechanical properties of soft living tissues are regionally heterogeneous. This heterogeneity can arise from pathologies, such as aneurysms in the aorta, or occur naturally, as in skin due to functional specialization. Nevertheless, homogeneous material properties are typically assumed in the finite element method (FEM). Here, we propose a novel methodology for incorporating spatially varying mechanical properties of soft biological tissues into FEM. In this method, a spatially continuous variation of material parameters is achieved by first generating smoothly varying material parameters using response averaging, followed by fitting continuous Fourier functions to the smoothed parameters. The proposed response averaging technique is validated using regional biaxial mechanical data from horse skin. The results suggest that incorporating mechanical heterogeneity leads to more realistic stress distributions.
Corin Seelemann, PhD candidate
Machine learning fractographic analysis of denatured collagen on human cortical bone
Abstract: Bone material is a composite primary composed of collagen (protein), calcium hydroxyapatite (mineral), and water. These components are organized hierarchically, creating a 3D structure that gives rise to ‘toughening mechanisms’. These include crack deflection, collagen fibrils spanning over the growing crack, and the formation of a microdamage process zone, rather than lengthening a single crack. However, in cases with aging or chronic oxidative stress (such as chronic kidney disease) bone can lose its ability to resist fracture and become fragile. The role of collagen in supporting bone fracture resistance, and how it can lose the capability to contribute is not fully understood. The present research applies machine learning techniques to examine images of human bone fracture surfaces, stained to detect denatured collagen. This allows analysis of how collagen contributes to fracture resistance.
