STRUCTURAL EVALUATION OF CERAMIC FEMORAL HEADS - EFFECT OF TAPER FRICTION, SUPPORT CONDITIONS AND TRUNNION COMPLIANCE

The outcome of a nonlinear finite element stress analysis of ceramic h eads for artificial hip joints is presented The analysis mainly covers the influence of taper friction, support conditions and trunnion modu lus of elasticity on the hoop stress distribution at the surface of th e head bore. The paper quantifies how much the maximum tensile stress decreases with increasing frictional coefficient, with stiffening of t he support and with stiffening of the trunnion material An appreciable rise of the maximum tensile upon unloading of the head is also shown for the case of cup support. The computational results are found in cl ose correspondence with photoelastic measurements of taper pressures a nd encourage the use, for preliminary design purposes, of an approxima te theoretical model retrieved from the literature.