A universal model for a frictionless elastic-plastic coated spherical normal contact with moderate to large coating thicknesses

A finite element analysis is used to investigate the elastic-plastic contact behavior of a coated sphere compressed by a rigid flat. The study concerns a wide range of material properties of the coating and substrate and covers the entire elastic-plastic regime of deformation including fully plastic contact. A transition interference, corresponding to maximum mean contact pressure, is presented that divides the elastic-plastic regime into two sub-regimes in terms of the load interference relation. An effective hardness of coated spheres that is load independent is properly defined. An appropriate normalization of the contact parameters is found enabling a universal elastic-plastic coated spherical contact model.