No abstract

No abstract

The Mohr-Coulomb (M-C) fracture criterion is revisited with an objective of describing ductile fracture of isotropic crack-free solids. This criterion has been extensively used in rock and soil mechanics as it correctly accounts for the effects of hydrostatic pressure as well as the Lode angle parameter. It turns out that these two parameters, which are critical for characterizing fracture of geo-materials, also control fracture of ductile metals Xue 2007;Barsoum 2006;Wilkins et al. 1980). The local form of the M-C criterion is transformed/extended to the spherical coordinate system, where the axes are the equivalent strain to fractureε f , the stress triaxiality η, and the normalized Lode angle parameterθ . For a proportional loading, the fracture surface is shown to be an asymmetric function ofθ . A detailed parametric study is performed to demonstrate the effect of model parameters on the fracture locus. It was found that the M-C fracture locus predicts almost exactly the exponential decay of the material ductility with stress triaxiality, which is in accord with theoretical analysis of Rice and Tracey (1969) and the empirical equation of Hancock and Mackenzie (1976), Johnson and Cook