Mechanical behavior of surface-coated bearing materials is analyzed and the possibilities of high tensile and shear stresses, which may lead to ultimate cracking of the coating, is investigated. An analysis for the stress distribution in layered elastic solids subjected to an arbitrary boundary loading is presented in terms of Fourier transforms of the Airy stress function. Stresses at the layer substrate interface as obtained by normal elliptical pressures at the layer surface are compared with those obtained by true pressure profiles. It is shown that for most cases the analysis for stress distributions in the materials of the layered solid may be performed by assuming an elliptical pressure at the boundary. However, the parameters for the ellipse should be obtained from the general solution to the contact problem. It is shown that extremely high tensile stress may be developed in the layer when the layer is relatively rigid compared to the substrate. Also, the shear stresses on the layer surface can induce high tensile stresses in the layer. These stresses will generally be responsible for brittle fracture or rupture of surface coatings used in many bearing applications.

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