Experimental analysis and modelling of c-crack propagation in silicon nitride ball bearing element under rolling contact fatigue

A comprehensive model for predicting fatigue failure probability of surface c-shaped cracks in silicon nitride ball bearing elements under rolling contact fatigue (RCF) has been presented in this paper. Firstly, three-dimensional finite element analysis (FEA) is used to determine the stress intensity factors (SIFs) along the front of crack by using fracture mechanics approach. Then the propagation uncertainty of c-crack is evaluated by using surrogate models built upon highly accurate finite element modelling for equivalent stress intensity factors. Finally, the Monte Carlo Simulations combined with surrogate models are used to predict the failure probability of rolling ball bearing element. Simulation results reveal that it is possible to reduce the failure probability of ball bearing element up to 95% by reducing the maximum crack size and enhancing the fracture toughness of the ball material. The modelling results have been verified by experimental studies showing that the current predictions of c-crack fatigue failures were consistent with the experimental results. Fatigues crack initiation and propagation is a significant failure mechanism within ceramic ball bearing elements. It presents design and durability challenges for both manufacturers and users. A three-fold approach, to simulate fatigue propagation of c-shaped crack in rolling contact ceramic bearing element presented in this paper, is novel and will solve major durability issues within ceramic ball bearing elements subject to rolling contact fatigue.