Simulation of deformation and fracture of materials with coatings of different thickness
The paper studies deformation and fracture of materials with coatings of different thickness. The boundary problem of mechanics is solved by the finite-difference method for plane strain conditions. The mechanical responses of the two components - steel substrate and boride coating - are described by models of an elastoplastic medium with isotropic hardening and of elastic-brittle fracture, respectively. The geometry of the substrate−coating interface is consistent with experimental data and is taken into account in an explicit form. Numerical experiments with varied coating thickness show that in a thin surface layer (~80 μm), the stress concentration near the substrate-coating interface increases with decreasing the coating thickness, i.e., as the interface is brought closer to the free specimen surface. It is found that this effect makes itself evident even at the elastic stage and increases as plastic deformation evolves in the substrate.