Comparison of seven ductile fracture initiation prediction models for stainless steel

Seven axisymmetric notched specimens extracted from stainless steel of yield strength 450MPa are tested under monotonic loading. The numerical simulation of all seven specimens is modeled in ABAQUS CAE, and the inbuilt constitutive model is used to capture the isotropic hardening behavior. The hardening parameters are calibrated until the numerical model simulates the exact behavior of load versus elongation obtained through experiments. The calibrated numerical model is used to determine the three fracture‐predicting parameters, namely stress triaxiality (T), equivalent plastic strain (PEEQ), and Lode angle (L). These three parameters are required in developing the fracture locus of 450 MPa Indian stainless steel. In addition, the study employs seven existing fracture prediction models for fracture initiation in all seven study samples. Using the determined values of T, PEEQ, and L at the fracture initiation point from the calibrated numerical simulation, the co‐efficient of all the seven selected models is calibrated. With the mean calibrated co‐efficient of all the specimens, the balanced error for all the models is calculated. With the help of the calculated balanced error, the efficiency of all the selected models in predicting the fracture initiation point is compared. Finally, the efficient model for 450 MPa Indian stainless steel is identified in this study.