Uncoupled fracture model of Q690 high‐strength steel based on stress triaxiality and Lode angle parameter

Abstract In order to accelerate the popularization of high‐strength (HS) steel, the fracture property of Chinese Q690 HS steel was investigated through experiments, numerical simulation, and model establishment in this paper. A three‐dimensional fracture dataset of Q690 steel based on “stress triaxiality‐Lode angle parameter‐fracture strain” was obtained by a hybrid method of experiment and simulation, illustrating that the ductility of Q690 steel under plane strain is lower than that under axisymmetric tension. Eight existing uncoupled fracture models were calibrated, and the Xue‐W model shows reasonable applicability on Q690 steel. To improve the accuracy of fracture prediction, a stress triaxiality and Lode angle parameter dependent uncoupled ductile fracture model was newly proposed, and a simplified version that can be conveniently calibrated without specially designed specimen was provided for engineering application. The proposed model and the simplified version were verified, respectively, and both can achieve satisfactory prediction on the fracture behavior of Q690 HS steel.