New Model for Ductile Fracture of Metal Alloys. I: Monotonic Loading

Abstract

In the absence of geometrical constraints, ductile fracture has been identified as the predominant mode of failure for structural elements under extreme loads, the prediction of which still represents considerable challenges. Ductile fracture of metals has only recently been recognized to be dependent on both stress triaxiality and Lode angle parameter. In this study, a new fracture model that is dependent on both stress triaxiality and Lode parameter is proposed. The developed model is proposed for the case of monotonic loading and is applicable to a wide range of stress states. The extension of the model to reverse loading, with complex loading history, is addressed in a parallel paper. The developed criterion is evaluated against data extracted from a series of multistress states monotonic experimental results for various metals, and a strong correlation is evident between the proposed model and experimental results in the entire range of the tested stress states. A detailed parametric study is conducted in order to show the effect of the model’s parameters on the fracture map. Comparative study among popular ductile fracture criteria and the proposed model in their prevailing ranges is also performed. The results show that the newly developed criterion, featuring only three parameters, does not lag behind its counterparts in any stress triaxiality ranges.