| For hard coated surfaces, it is important to control the crack initiation at the coating/substrate interface to prevent delamination or spalling. Yielding is one of the most important driving forces that control crack initiation and propagation at the interfaces. Therefore, it is essential to know the location of initial yielding. In the current study, the local yielding of a hard coating completely bonded on a two dimensional homogeneous elastic half space under sliding contact in plane strain condition is analyzed. The local yielding is defined by von Mises yield criterion and the stress distribution is generated by finite element analysis. The python script used for the FEA analysis is validated and verified with experimental and analytical solutions presented by previous researchers. Upon verification, a thorough quantitative comparison is made between the single-layer, multilayer, and functionally graded coating/substrate systems. Subsurface stress distribution reveals that the functionally graded coating exhibits the lowest risk of yielding and yielding risk decreases if coating thickness increases. The effect of different parameters such as coating thickness, coating and substrate elastic moduli and yield strength on yielding behavior is studied. Finally, the best design combination of stiffness ratio for FGM coating is investigated for fixed surface elastic moduli. |
