A finite element analysis was used in order to investigate the elastic contact of a coated sphere compressed by a rigid flat. A proper normalization of the dimensional contact area and maximum stresses in the coating and in the substrate was used to obtain a universal model of the elastic contact. This model provides relation between the contact area and the interference for a wide range of mechanical and geometrical properties, which is different from the classical Hertz relation for homogeneous sphere compressed by a rigid flat. This model also provides a new approach of defining the limit of elasticity in the coated system, based on the calculation of the maximum von Misses stresses in the substrate and the coating from their mechanical and geometrical properties as well as the interference.
