Numerical Investigation Of Fluid-Solid Coupling And Chemo-Mechanical Coupling Problems For Porous Materials

Biological tiusses, as a kind of porous media, are often considered as a mixture of fluid and solid phase, whose macroscopic properties depend on their microstructural information. In this dissertation, fluid-solid coupling behavior and chemo-mechanical coupling behavior for porous media are investigated.Based on Biot consolidation theory, fluid-solid coupling behavior of vertebra and intervertebral disc under external force is studied. The vertebra and intervertebral disc are considered as porous materials, consisting of solid skeleton and pore liquid. An axisymmetric form for equilibrium equations and continuity equation are built. The equivalent integral form and FE equations are obtained by applying virtual work principle and Galerkin weighted residual method, while time is discreted by linear difference procedure.Based on the definition of chemical potential, the first law and the second law of thermodynamics, the constitutive relationship of chemo-mechanical coupling are presented. Euler equations are obtained by applying integration by parts to energy functional. It is indicated that the chemo-mechanical coupling system is closed. It is certificated that physical quantity unit is matched in every equations. The equivalent integration forms and weak forms of the governing equations are derived by using weighted residual method. This investigation is helpful to understand the coupling mechanism of chemical and mechanical behavior. Chemo-mechanical coupling procedure is programmed based on governing equations and FE linear equation set is solved by PCG method. The chemo-mechanical coupling behaviors of nucleus pulposus and articular caritilage are analyzed.This work is significant to provide theory and FE mothod to simulate fluid-solid coupling behavior and chemo-mechancial coupling behavior for biological materials.