Investigation on articular cartilage deformation properties affected by loading rates

By means of the investigation on the articular cartilage deformation properties affected by the different loading rates, the injury mechanism of the natural cartilage by the abnormal stress is discussed. The compression experiment on the cartilage deformation at three loading rates was carried out on the UMT-2 multi-functional testing rig, and the corresponding finite element model was established. The results show that the elastic modulus undergoes initially a sharp decline and then a slow incline with the increase strain. The strain measured from the experiment is within 0.025 of the finite element precision. As the loading rates are 0.01MPa/s and 0.0067MPa/s, the differences of the pore pressure carried by the cartilage matrix and the elastic modulus are negligible. But as for the loading rate of 0.02MPa/s, the corresponding pore pressure and elastic modulus are markedly different. Loading rate plays a significant role on the cartilage deformation and pore pressure, but while the loading rate is below a certain value, the dependence of the cartilage deformation on the loading rate is reduced, indicating that these results could be helpful to deeply understand the injury mechanism of a cartilage matrix by the abnormal stress rate.