Calibration of constitutive equations under conditions of large strains and stress triaxiality

Constitutive equations were calibrated to improve their application in assessing a stress field in front of a crack under the conditions of large strains and stress triaxiality. The Bai-Wierzbicki method was adopted, and certain changes and new terms were introduced to incorporate material softening. Five shapes of specimens were tested to cover a wide range of stress triaxiality conditions and Lode factors. Tests were performed at three different temperatures, namely, +20 °C, -20 °C, and -50 °C, and on three different materials obtained by three different heat treatments of S355JR steel.