Study on local failure mechanism considering stress triaxiality factor

The failure mode so called local failure could occur at structure discontinuities. Local failure is caused from Von Misses stress and hydrostatic stress. So the triaxiality factor considering hydrostatic stress has been introduced to evaluate local failure based on Misses type criteria. However the mechanism of local failure has not been clarified. For this reason it is not easy to say that triaxiality factor is properly applied to evaluate local failure. Thus the purpose of this study is to clarify the relation of local failure and triaxiality factor with tensile tests of notched bars and FEM simulation. As a result, it is clarified that triaxiality factor doesn't always indicate difficulty occurs of plastic deformation. Furthermore it is clarified the relation of local failure and triaxiality factor by introducing the Von Misses stress - hydrostatic stress plane and fracture curve. (author)