title: Effects of friction on the unconfined compressive response of articular cartilage: a finite element analysis.
abstract: 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.
authors.affiliation: Department of Mechanical Engineering, Aeronautical Engineering, and Mechanics Rensselaer Polytechnic Institute, Troy, NY 12180.
authors.forename: R L
authors.initials: RL
authors.lastname: Spilker
authors.forename: J K
authors.initials: JK
authors.lastname: Suh
authors.forename: V C
authors.initials: VC
authors.lastname: Mow
mesh_terms: D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000502:physiology*; D008954:Models, Biological; D011312:Pressure; D013314:Stress, Mechanical