A method for the orthotropic coating-substrate system: Green׳s function for a normal line force on the surface

As for the increasing usage of orthotropic and composite materials as a coating of conventional materials in structural applications, a method based on the Green׳s function for the orthotropic coating-substrate system under a normal line force is proposed in this paper. The coating and substrate are modeled as an infinite layer and a semi-infinite substrate respectively. they are perfectly bonded or in smooth contact at the interface. Based on the general solution of orthotropic material, the corresponding harmonic functions with undetermined constants are constructed. Full elastic field can be obtained by substituting these harmonic functions into the general solution. The undetermined constants can be determined by the boundary conditions on the surface and the compatibility conditions at the interface between the coating layer and the semi-infinite substrate. Numerical results are given to show the accuracy and efficiency of this method in studies on the interface effect, interface debonding, coating tensile failure and the relationship between the orthotropic elastic moduli with the stress distributions. The proposed method can suggest possible mechanisms by which orthotropic coated structures can be designed for engineering applications.