Stress analysis for a thin film bonded to an orthotropic substrate under thermal loading

Abstract

In this paper, the interaction between an isotropic thin film and an orthotropic substrate is considered under the plane strain state. The perfectly bonded thin film is exposed to a predefined temperature gradient. The strain compatibility condition and the plane elasticity formulation are utilized to extract the governing integral equations. Employing the Gauss- Chebyshev discretization method, the interfacial shear as well as the flexural surface in-plane stresses are determined. The influences of the material stiffness and the orthotropy parameters on both surface and subsurface stresses are investigated. The numerical results confirm that the proper adjustment of the orthotropic substrate properties can alleviated the severe stress gradients. The results indicate that the surface in-plane stress tensile peak significantly decreases if the stiffness of the orthotropic half-plane along the film interface is lower than its corresponding value through the depth. Also, the maximum von Mises stress in the substrate decreases about 50% for an orthotropic material possessing a large shear parameter.