Abstract: Coating technology is usually used to protect the surfaces of machine parts and cutting tools,avoid wear and to prolong parts' fatigue life.The subsurface stress distribution in the coating significantly influences the sur- face failure of parts.In this paper,polycarbonate/epoxy was used as a coating/substrate system,and some photoe- lasticity experiments were carried out to collect the photoelastic fringe patterns of the coating/substrate system sub- jected to loads.Then,a finite element model of the coating/substrate system was established with Abaqus,and the stress distribution of the system varying with coating thickness and contact load was analyzed.Experimental and theoretical results show that (1) in contact stress field,the maximum shear stress appears in the subsurface rather than on the surface and extends to the substrate as the load increases; (2) for the system with different coating thickness,the stress suddenly increases at the interface of the coating to the substrate,which is caused by the difference in material properties between the coating and the substrate; and (3) stress distributions obtained via photoelasticity experiment are basically consistent with those obtained via finite element method.

Key words: photoelasticity experiment, coating/substrate, contact stresses, finite element method