CONTACT MECHANICS OF ULTRAHIGH-MOLECULAR-WEIGHT POLYETHYLENE FOR ARTIFICIAL KNEE-JOINT

To investigate the wear mechanism of an ultrahigh-molecular-weight pol yethylene (UHMWPE) for an artificial knee joint, the pin-on-disk-type wear test and the numerical analysis of contact mechanics of the UHMWP E were performed. In this analysis, to calculate the cyclic deformatio n of the UHMWPE, a constitutive equation for cyclic plasticity was use d. In the initial stage of deformation, the UHMWPE was deformed only p lastically; beyond this stage, however, wear of the UWMWPE progressed rapidly with weight loss. In this initial stage, shear stress and equi valent plastic strain were accumulated by cyclic loading on the contac t surface of the UHMWPE and it was expected that the microcracks that create wear particles would be generated on the surface.