Poisson Contraction and Fiber Kinematics in Tissue: Insight from Collagen Network Simulations

Connective tissue mechanics is highly non-linear, exhibits a strong Poisson effect and is associated with significant collagen fiber re-arrangement. Although the general features of the stress-strain behavior in tension and compression and under uniaxial, biaxial and shear loading have been discussed extensively, especially from the macroscopic perspective, the Poisson effect and the kinematics of filaments have received less attention. In general, the relationship between the microscopic fiber network mechanics and the macroscopic experimental observations remains poorly defined. The objective of the present work is to provide additional insight into this relationship. To this end, results from models of random collagen networks are compared with experimental data on reconstructed collagen gels, mouse skin dermis and the human amnion. Attention is devoted to the mechanism leading to the large Poisson effect observed in experiments. The effect of fiber tortuosity on network mechanics is also discussed. A comparison of biaxial and uniaxial loading response is performed. Such model validation is essential since these can be used to evaluate parameters important in tissue mechanics which are not accessible experimentally.

link : http://biomechanical.asmedigitalcollection.asme.org/article.aspx?article...