Dynamic flow stress of pure polycrystalline aluminum: Pressure-shear plate impact experiments and extension of dislocation-based modeling to large strains (original) (raw)
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The mechanical loading-deformation relation of elastin and collagen fibril bundles is fundamental to understanding the microstructural properties of tissue. Here, we use multiphoton microscopy to obtain quantitative data of elastin and collagen fiber bundles under in situ loading of coronary adventitia. Simultaneous loading-imaging experiments on unstained fresh coronary adventitia allowed morphometric measurements of collagen and elastin fibril bundles and their individual deformation. Fiber data were analyzed at five different distension loading points (circumferential stretch ratio λθ = 1.0, 1.2, 1.4, 1.6, and 1.8) at a physiological axial stretch ratio of λaxial = 1.3. Four fiber geometrical parameters were used to quantify the fibers: orientation angle, waviness, width, and area fraction. The results show that elastin and collagen fibers in inner adventitia form concentric densely packed fiber sheets, and the fiber orientation angle, width, and area fraction vary transmurally. The extent of fiber deformation depends on the initial orientation angle at no-distension state (λθ = 1.0 and λaxial = 1.3). At higher distension loading, the orientation angle and waviness of fibers decrease linearly, but the width of collagen fiber is relatively constant at λθ = 1.0–1.4 and then decrease linearly for λθ ≥ 1.4. A decrease of the relative dispersion (SD/mean) of collagen fiber waviness suggests a heterogeneous mechanical response to loads. This study provides fundamental microstructural data for coronary artery biomechanics and we consider it seminal for structural models.
Characterisation of Mechanical Properties of Human Pulmonary and Aortic Tissue
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The aim of this study is to characterise the mechanical properties of aortic and pulmonary arterial tissue, thereby comparing both tissue types and investigating the effect of lung-affecting disease on the mechanical behaviour of pulmonary arteries. Force-controlled, planar biaxial tensile tests were performed on human tissue samples collected from donors and receptors undergoing lung transplantation. In total 8 pulmonary donor, 6 pulmonary receptor and 6 aortic donor samples were tested and analysed. Donor samples are considered to be healthy, while receptors provided pathological tissue. The stiffness and strength of each sample were calculated from the stress-strain curves and a statistical analysis was performed between the three tissue groups (pulmonary donor, pulmonary receptor and aortic donor). The stiffness of aortic donor tissue was found to be significantly higher than for pulmonary donor tissue (p < 0.01) at physiological systolic stresses. The same could be observed ...
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