Effects of Boundary Conditions on Planar Biaxial Mechanical Testing and Modeling of the Mechanical Behavior of Planar Collagen Gels

• Main Authors: Guan-WenChen, 陳冠文
• Other Authors: Jin-Jia Hu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/90413145969026006614

碩士 === 國立成功大學 === 生物醫學工程學系 === 100 === This thesis is composed of two parts. In the first part, we investigated the effects of specimen geometry on the apparent mechanical properties of cruciform-shaped specimens. In particular, finite element simulation was used to illustrate the distribution of strains, the uniformity of strain, and the failure indices on the specimen. The results were compared with our previous results that were based on digital image correlation and the associated deformation measurement. We found that if the square-shaped specimens were attached to the loading system by sutures the uniform-strain area was greatest and the stress in the central region where the strain is measured was most accurately measured. The limited suture retention strength of collagen gels, however, prohibits the use of suture attachment. Cruciform-shaped specimens with appropriate corner fillets was found to be the optimal geometry for the mechanical testing of collagen gels as it meets the failure indices and provides acceptable uniform-strain area in the central region of the specimen. In the second part, we used hyperelastic models to fit biaxial mechanical properties of collagen gels, which was determined in our previous study. Two models were tested: the Fung model and the Lanir model. In particular, the two models were used to model and compare mechanical properties of cell-seeded collagen gels cultured under a variety of mechanical constraints. We found that Fung model provides better fitting than Lanir model for most of gels. We examined the anisotropy of the tissues by calculating the ratio of material stiffness based on Fung model. Although the Lanir model was not as good in terms of fitting, its material parameters have physical meaning and has great potential to understand the underlying microstructure of the tissue.