Experimental analysis and modeling of subsurface cracks with random propagation for ceramic material on rolling contact fatigue

During the degradation of critical rotating components using ceramic materials, due to the uncertainty of the failure generation mechanism, the high nonlinearity of failure evolution and the diversity of failure modes, the unpredictability of sudden failure triggered by random propagation of subsurface cracks poses a great challenge to the operation and maintenance. Based on the finite element model reconstructed from fatigue tests, an early failure evolution model for ceramic bearings considering random propagation of subsurface cracks is constructed in this paper. Throughout the work, the position coordinates of critical nodes characterizing the degree of crack propagation (alpha, beta, gamma) are introduced to visualize the influence of propagation on the finite element of crack front during the whole rolling contact process, whose errors (epsilon) are stabilized at 10%. Then Monte Carlo Simulation is used to generate the randomness events of crack propagation, which satisfies the uncertainty characteristics of early failure initiation and propagation under actual working conditions. The results show that the first deflection shows strong randomness. Afterwards, the main cracks move away from the surface in mixed fracture mode, and finally form abrupt spall after several deflections. The proposed model not only reveals the sudden failure mechanism of ceramic bearing under uncertain crack propagation, but also effectively evaluates performance degradation of critical rotating components using ceramic materials.