A numerical study of the behaviour of surface cracks under dry-sliding conditions

The shape and amount of the surface roughness of a machine part is based on the manufacturing processes. The irregularities cause serious stress concentrations due to the loads acting on the surface. When the loads effect on the surface repeatedly, the irregularities penetrate to turn into a crack. The load may act as normal and/or fractional forces. The latter is caused in general due to friction under rolling–sliding contact conditions. In this study, the behaviour of surface cracks under the normal and tangential loads were analysed. Three angular location for the crack is considered (i.e. −π/4, π/2 and π/4) The problem is considered under condition of linear elastic fracture mechanics and the finite element method was used for numerical solution. The intensity factors at crack tip, KI and KII, were calculated using displacement correlation method. Maximum principal stress theory was used to determine the direction of crack propagation. Effect of the friction coefficient on the stress intensity factors KI and KII and crack growth direction was also investigated.