Contact mechanics problem between an orthotropic graded coating and a rigid punch of an arbitrary profile

Singular integral equation (SIE) and finite element methods are developed for sliding contact analysis of a finite thickness orthotropic graded coating, which is perfectly bonded to an isotropic substrate. Orthotropic stiffness coefficients of the coating vary exponentially through the coating thickness. The coating is assumed to be loaded by a frictional rigid punch of an arbitrary profile. In the SIE formulation, governing partial differential equations are derived in accordance with the theory of plane elasticity. Applying Fourier transformation techniques, the problem is reduced to a singular integral equation of the second kind. Flat and triangular punch profiles are considered in the formulation. The integral equation is solved numerically through an expansion-collocation technique. Roots of Chebyshev polynomials of the first kind are employed as collocation points. The posed contact problem is also solved by means of the finite element method. The augmented Lagrange algorithm is applied in the iterative solution procedure. Comparisons of the contact stresses obtainedby singular integral equation and finite element methods demonstrate that the findings of these two separate techniques are in excellent agreement. Further numerical results are generated to be able to assess the influences of coefficient of friction, non-homogeneity constants, relative coating thickness, and degree of orthotropy upon the contact behavior of the coating-substrate system. (C) 2017 Elsevier Ltd. All rights reserved.