Quantification of pre-strain effect on ductile fracture and application to irradiation embrittlement problems

This paper proposes a numerical method to predict fracture resistance of pre-strained materials, which is further applied to predict fracture resistance of irradiation-embrittled materials. The proposed method is based on a multi-axial fracture strain damage model using the fracture strain locus and critical damage. The key point is that the pre-strain effect on the critical damage is predicted using the pre-strain effect on plastic strain energy density of tensile data. Application to published experimental data for pre-strained SUS316 and SM490A shows that the predicted fracture toughness results agree well with experimental data. Based on published experimental results that the pre-strain effect on tensile and fracture toughness properties is similar to the irradiation effect, the proposed model is further applied to predict fracture toughness of irradiation-embrittled SUS316 material. Although only numerical simulation results are available, they show that maximum loads for irradiated specimens are higher than those for un-irradiated specimens. Furthermore, the effect of irradiation gradient along the crack growth direction is not so significant.