A further investigation of mixed mode loading center crack problem

In this paper, a BEM model which describes the reduced mode II and enhanced mode I stress intensity factors of the center crack problem caused by fracture surface roughness is reenforced. The dilatant boundary conditions (DBC) are assumed to be idealized uniform sawtooth crack surface and effective Coulomb sliding law. Three types of crack boundary conditions are investigated and well defined: (1) open crack, (2) DBC crack with elastic tip, (3) DBC crack with plastic tip. In plastic case, the 2D Newtonʹs method is described in the iteration process of getting the length of plastic zone. The method of obtaining the effective mode I and II stress intensity factors of the center crack problem and the boundary conditions of each different case as well are carefully and well described. The resulting crack opening displacement, crack sliding displacement and the stress distributions along the interface show the fracture surface interference of a rough DBC crack. The numerical results show the potential application of the BEM model to the effects of mixed mode loading center crack problem with various boundary non-linearities due to rough contact and plasticity.