Planar multi-body dynamic investigations of dry artificial hip joints with a clearance

Abstract

An assessment of the applicability of modified Hertzian contact and friction-induced vibration to prosthetic hip bearings as clearance joints is investigated throughout this work. Moreover, the main novelty of the present study is suggesting a robust and simple-to- implement multibody dynamic mechanism which could cope with the usual difficulties of available models due to the presence of muscles, tendons and ligaments in bio-multibody dynamic models. Nonlinear and non-smooth dynamic governing equations of the multibody mechanism are solved by employing an explicit numerical approach, adaptive Runge-Kutta- Fehlberg method, to discretize the time interval of interest. A FFT frequency analysis of the audible sounds from CoC hip acceleration is carried out to examine hip squeaking. In addition, the ball center trajectory associated with a normal walking cycle and the frequencies in which hip implants squeak are studied. The effects of hip implant sizes and initial position of the hip ball on the system response are also considered.