Finite element algorithm reproducing hip squeak measured in experiment

Abstract In this study, the frequency spectrum of squeak noise in hip joint system is measured in experiment. The numerical reproduction of hip squeak signal involves the formulation of the finite element geometry, the analytical contact kinematics such as Hertz theory and Coulomb's law and the mode-discretization. For general approach, the contact kinematics are analytically modeled to easily adjust the contact location, the contact area, the rotation direction, the pressure distribution, the friction law, and so on. Furthermore the friction stress vectors act on the 3-dimensional spherical contact surfaces where they can be divided into the steady-sliding and its transverse slip directions. Numerical calculations for the various contact parameters are conducted to investigate the possibility of hip squeak occurrence and the nonlinear oscillations after the onset of squeak are also solved. In the transient analysis, the periodic limit cycle of hip squeaking is shown to be the stick-slip type oscillation. Then the numerical frequency spectrum is qualitatively compared with hip squeak signal measured in experiment. The stick-slip oscillation during hip squeaking and its contact behavior will be also discussed over the contact area within one period.