Thermo-elasticity analysis of coating-substrate systems under local thermal shocks and impact loads considering imperfect thermal and mechanical bonding

Abstract

In this study, the transient thermoelastic response of a coating-substrate system under simultaneous local thermal shocks and in-plane mechanical impact loads is explored. An abrupt localized thermal shock in the form of heat flux irradiation is imposed on the external surface of the ceramic coating. Besides, the local normal and shear impact loads are exerted on the top face of the coating as well. To consider the lagging nature of the heat flux flow through the layers and better scrutinize the transient responses of the layers, the Dual-Phase-Lag (DPL) heat conduction equation is employed. Interface bonding status is articulated in terms of both thermal and mechanical imperfections. The transient temperature fields attained via the DPL conduction equation are annexed to the equations of motion to construct the coupled non-homogeneous governing equations. The exact solutions of the governing equations are derived by means of the Laplace and Fourier integral transforms. The striking influences of different thermal shocks, the thermal shock effecting time, the localized impact loads and combined thermomechanical loads on the variations of field variables are comprehensively examined. The outcomes clarify that the type of thermal shock and impact loads, i.e. concentrated or distributed forms, play a key role in the transient response of the temperature/stress fields inside the layers. Meanwhile, the thickness of ceramic coating and the interface imperfection have paramount roles in the temperature/thermal stress fields and the system responding intensity.