A combined wear and crack nucleation-propagation methodology for fretting fatigue prediction

This paper presents a finite element based methodology for predicting the effects of fretting wear on crack nucleation and propagation under fretting fatigue conditions. The method combines wear modelling with critical plane, multiaxial prediction of crack nucleation and linear elastic fracture mechanics prediction of short and long crack propagation. A global-sub modelling finite element approach is employed for efficient wear and crack propagation simulation. The results are compared with available fretting fatigue test data and previous critical plane wear-based predictions (which neglect the propagation phase) for Ti-6Al-4V across a range of slip amplitudes. It is shown that the separate modelling of nucleation and propagation in the presence of wear can significantly affect the prediction of fatigue life under both partial slip and gross sliding conditions. It is predicted that wear under gross sliding conditions significantly retards propagation rate whereas wear under partial slip conditions is predicted to increase crack propagation rates across the slip zone. These results are consistent with observed phenomena of fretting fatigue cracking.