The dependence of Weibull parameters on preloads and its implication on brittle fracture probability prediction using a local criterion

•It is shown that only reference stress changes with changing preload level and type.•A linear relationship was derived to modify reference stress due to preload effects.•The relationship was used for different geometries, material and loading conditions.•The proposed procedure is simple and practical for any complex structures and loadings.

A linear applicable relationship is proposed to improve the cleavage failure probability prediction of preloaded specimens using the modified Beremin model. Maximum stress triaxility factor shows fracture load independency for enough high loads and a good sensitivity to crack tip stress changes due to residual stresses and preloads. Hence, it is selected as representative of crack tip stress state. Using recalibration for six experimental datasets of CT including different levels of pretension and precompression shows that only reference stress changes with changing the preload level and type. A linear relationship is derived to modify the reference stress for the preloaded cases as a function of maximum stress triaxiality factor which can be easily computed from the FE analysis. Using the proposed relationship simply leads to a considerable improvement for failure predictions in all cases with different geometries, materials and preloading conditions.