Numerical analysis of the contact stresses developed during the indentation of coated systems with substrates with orthotropic properties

Many works in the literature have analyzed the contact stresses developed during the indentation of coated systems. In general, the damage observed in systems with soft substrates is characterized by circular cone cracks that propagate at the edge of the indentations. In systems with soft substrates, recent works have also shown that the amount of substrate indentation pile-up presents direct relationship with a peak in radial stresses at film surface and, consequently, with the amount of indentation circular cracks.In this work, a series of finite element analyses was conducted to simulate the indentation of systems with an elastic film and an elastic-plastic substrate. Two values of film thickness were selected and, in each simulation, substrates were divided into two layers with different plastic properties. The layer on the bottom was considered isotropic and the layer attached to the film presented plastic properties along the loading direction (z) that were different from the plastic properties along the radial and tangential directions. Different ratios between axial and radial/tangential properties were considered.Results indicated that the amount of substrate pile-up and, consequently, the peak in radial stresses at film surface, could be significantly reduced in coated systems with substrates with orthotropic plastic properties.