Spilker R L, Suh J K, Mow V C
Department of Mechanical Engineering, Aeronautical Engineering, and Mechanics Rensselaer Polytechnic Institute, Troy, NY 12180.
J Biomech Eng. 1990 May;112(2):138-46. doi: 10.1115/1.2891164.
A finite element analysis is used to study a previously unresolved issue of the effects of platen-specimen friction on the response of the unconfined compression test; effects of platen permeability are also determined. The finite element formulation is based on the linear KLM biphasic model for articular cartilage and other hydrated soft tissues. A Galerkin weighted residual method is applied to both the solid phase and the fluid phase, and the continuity equation for the intrinsically incompressible binary mixture is introduced via a penalty method. The solid phase displacements and fluid phase velocities are interpolated for each element in terms of unknown nodal values, producing a system of first order differential equations which are solved using a standard numerical finite difference technique. An axisymmetric element of quadrilateral cross-section is developed and applied to the mechanical test problem of a cylindrical specimen of soft tissue in unconfined compression. These studies show that interfacial friction plays a major role in the unconfined compression response of articular cartilage specimens with small thickness to diameter ratios.
采用有限元分析方法来研究压板-试样摩擦对无侧限压缩试验响应的影响这一先前未解决的问题；同时也确定了压板渗透性的影响。有限元公式基于用于关节软骨和其他含水软组织的线性KLM双相模型。将伽辽金加权残值法应用于固相和液相，并通过罚函数法引入本质上不可压缩的二元混合物的连续性方程。根据未知节点值对每个单元的固相位移和液相速度进行插值，得到一个一阶微分方程组，使用标准数值有限差分技术求解该方程组。开发了一种四边形横截面的轴对称单元，并将其应用于无侧限压缩状态下圆柱形软组织试样的力学测试问题。这些研究表明，界面摩擦在厚度与直径比小的关节软骨试样的无侧限压缩响应中起主要作用。
