The coupled thermoelastic instability of FGM coatings with arbitrarily varying properties: in-plane sliding

The hot spot caused by frictional heat and thermal contact resistance is one of the most important reasons for hot-cracks and brake failure in brake systems. This paper simulates the brake system as a functionally graded material (FGM) coated half-plane sliding against a homogeneous half-plane. The motivation of using the FGM coating is to improve the coupled thermoelastic instability (TEI) of the brake system due to the thermal contact resistance and frictional heat. The thermoelastic properties of the FGM coating are assumed to vary arbitrarily along the thickness direction. The homogeneous multi-layered model is employed to simulate arbitrary properties of the coating. The perturbation method and transfer matrix method are used to derive the characteristic equation of the coupled TEI problem. The effects of the thermal contact resistance, friction coefficient, heat generation factor and different gradient types of the FGM coating on the stability boundaries are discussed in detail. The results show that the stability boundary is sensitive to the varying thermal parameters of the FGM coating, and an appropriate gradient type can adjust the coupled TEI of the sliding system.