Predicting Hertzian fracture

The procedure for calculating the probability of initiation of a Hertzian cone crack as a function of indenter load and indenter radius is demonstrated and the results compared with experimental data. Such a procedure brings together the energy balance and flaw statistical explanations of Auerbach’s law. The method relies on the application of Weibull statistics in the diminishing indentation stress field. It is shown how strength parameters obtained from bending tests on bulk specimens may be used within the analysis for predicting the presence of surface flaws which lead to the initiation of a cone crack. The procedure is shown to apply to both cylindrical punch and spherical indenters.