Affiliations: BioSyntech Inc., Laval, Quebec, Canada | Institute of Biomedical Engineering, Departments of Chemical & Mechanical Engineering, Ecole Polytechnique, Montreal, Quebec, Canada
Note: [] Address for correspondence: LePing Li, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada T2N 1N4. Tel.: +1 403 220 8525; Fax: +1 403 284 3553; E‐mail: [email protected].
Abstract: Collagen fibril reinforcement was incorporated into a nonlinear poroelastic model for articular cartilage in unconfined compression. It was found that the radial fibrils play a predominant role in the transient mechanical behavior but a less important role in the equilibrium response of cartilage. The radial fibrils are in tension and can be highly stressed during compression, in contrast to low compressive stresses in all directions for the proteoglycan matrix after a small initial compression. The strain dependent fibril stiffening produces strong nonlinear transient response; the fibrils provide extra stiffness to balance a rising fluid pressure and to restrain stress increase in the proteoglycans. The fibril reinforcement, induced by the fluid pressure and flow, also accounts for a complex pattern of strain‐magnitude and strain‐rate dependence of cartilage stiffness.
