Finite element simulation of fretting wear- fatigue interaction in spline couplings

This paper describes a finite element based method for simulating the effects of material removal, associated with fretting wear, on fretting fatigue parameters in a spline coupling. An incremental wear simulation technique is implemented with a single tooth finite element model of the coupling for symmetric loading, assuming equal wear on all teeth, using a comparatively coarse mesh model, for computational efficiency. A surface interpolation technique is implemented to map the predicted distributions of wear onto a non-symmetric, 360u (18-tooth) model, with detailed refinement on one tooth, to predict the effect of wear on the evolution of stress, strain and fatigue parameters and on subsequent life prediction. The life prediction is based on a critical plane multiaxial fatigue parameter approach, along with cumulative damage for combined load cycles and for wear induced changes in the fatigue parameters. Furthermore, the effect of wear due to the rotating bending moment and fluctuating torque on fretting fatigue damage accumulation is presented. Low frequency, torque and axial loading induced wear, leading to gross slip conditions on all teeth, is predicted to reduce fretting fatigue parameters and hence increase life. In contrast, higher frequency, rotating moment and fluctuating torque induced wear, corresponding to partial slip conditions, is predicted to increase fretting fatigue parameters away from the contact edges and hence lead to fretting fatigue cracking away from the contact edges and, for the case studied here, to a reduction in predicted life, as observed experimentally. The results are interpreted vis-à-vis published test data for scaled aeroengine splines.