Crack propagation of a thin hard coating under cyclic loading: Irreversible cohesive zone model

The numerical study of the fatigue behaviour steel and light alloy substrates when coated with thin hard coatings is limited. This paper aims to investigate failure mechanism coating system by observing initiation propagation cracks within under cyclic loading. model composed three layers: TiN coating, a case-hardened diffusion zone H11 substrate. cohesive elements were arranged evenly in horizontal direction vertically through thickness layer order observe crack propagation. was indented spherical indenter 300 ?m radius. Both substrate characterised as being homogenous, elastic properties followed linearly-hardening plastic behaviour. irreversible model, allowing for local degradation material be incorporated into employed simulate It observed that initiated at edge contact area between surface early stage loading cycles, then progressed rapidly layer. deepest found 1.4 below top surface. has demonstrated can used track evolution loading, therefore capability predict bearing capacity conditions.