Partial slip contact of materials with vertically aligned cracks near surface

This study develops a numerical model for the partial slip contact of fractured substrates with embedded cracks aligned vertically. Each crack is assumed to be a mixed mode one (modes I and II) with separated faces and closed tips. The discrete dislocation technique is adopted to simulate the crack by a distribution of climb and glide dislocations with unknown densities, which are iteratively determined in a subroutine based on the conjugate gradient method. Tangential displacements induced by the dislocations are integrated into the model to investigate the effects of cracks on the tractions in slip and stick regions. The stress intensity factors are determined based on the solutions of dislocation densities. The model is capable of solving multiple-crack problems with the consideration of interactions among cracks and contact bodies, and the effects of cracks on the loading distribution and stress fields are discussed in detail. The contact loading produces a tendency to close crack faces and a vertical crack prevents surfaces from deforming. The interactions of the normal and tangential forces lead to the shift of the stresses along the direction of friction. The conclusions provide insights into the behaviors of fractures near a material surface under fretting contact conditions.