Nonlinear vibration and dynamics of ceramic on ceramic artificial hip joints : a spatial multibody modelling

The present study investigates nonlinear vibration and dynamic behaviour of a ceramic-on-ceramic hip implant. The aim of this research is to firstly gain a better understanding of hip squeaking and vibration and secondly to investigate the effect of friction on contact point path during normal gait. For this purpose, a spatial multibody dynamic hip model was developed, using a friction-velocity constitutive law combined with a Hertzian contact model. Furthermore, the physiological three-dimensional rotation angles and forces are taken into account to calculate tangential and normal contact forces, respectively. Comparing the outcomes with that available in the literature allowed for the validation of our approach. It was shown that the cause of hip squeaking is friction-induced vibration owing to different phenomena such as stick-slip friction, negative-sloping friction and contact force changes. Moreover, friction-induced vibration does significantly change contact point path during the gait when compared to non-friction analysis