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 unirradiated specimens. Furthermore, the effect of irradiation gradient along the crack growth direction is not so significant.