A simple method to determine opening stress for the cracked plate considering thickness effect

In this paper, an approach is proposed to determine crack opening stress (COS) based on the variable quantity of maximum crack opening displacement (VMCOD) considering thickness effect. Based on the three-dimensional elastic-plastic finite element analysis of center cracked tension (CCT) specimens and single-edge cracked tension (SET) specimens, the explicit expressions of relationship between COS and VMCOD are put forward, considering the effect of specimen thickness, crack length, stress ratio, Young's modulus, yield stress and strain hardening. These expressions avoid adopting parameters around crack tip and are applicable to different specimen thicknesses. Further studies show these relationships can be applied to calculate the effective stress intensity factor range and predict crack growth rates for plates of different thicknesses, which correlate well with experimental results. •We propose a method to predict the crack opening stress (COS) considering thickness effect.•The variable quantity of maximum crack opening displacement (VMCOD) is introduced.•The explicit expressions between COS and VMCOD consider the effect of crack size, stress ratio and material properties.•The method avoids adopting parameters around crack tip and is applicable to different specimen thicknesses.•The expressions are applied to predict crack growth rates for different thicknesses, which agree well with experimental data.