On a new torsional wear tester, the torsional wear tests of bovine hip joint articular cartilage flat against Al3O2 femoral heads(with diameter of 28 mm) were carried out with various angular displacement amplitudes ranging from 0.5°to 5°and imposed loads ranging from 5 to 50 N. Based on the analysis of the frictional kinetics of torsional fretting, the wear were observed by electron microscope(SEM) and Hematoxylin-Eosin(HE) stain, and the damage characteristics of joint articular cartilage also were discussed. The results indicated that two kinds of T-θ curves(i.e. parallelogram and elliptical curves) were observed during the process of torsional wear. Parallelogram mainly occurred at slip status(SS) and elliptical loops appeared at partial slip status(PSS). The damage of bovine hip joint articular cartilage under torsional fretting PSS was very slight and the folding was the main damage. Under SS, along the radial direction, the wear scar could be divided to three zones, i.e. the adhesive zone, folding and micro-crack zone, and delamination zone, respectively. The wear mechanism performed as delamination and micro-cracking.
