Non-fourier thermal fracture analysis of a griffith interface crack in orthotropic functionally graded coating/substrate structure

Abstract

Serving as thermal barrier coatings in the harsh environment, functionally graded materials are usually subject to the extremely high temperature gradient, under which circumstance the classical Fourier's law breaks down and the non-Fourier effect becomes pronounced. The configuration of an orthotropic functionally graded coating bonded to the homogenous substrate containing a Griffith interface crack is considered in this work. The dual-phase-lag heat conduction theory is adopted to analyze the transient heat conduction and the resulting thermal stress intensity factors of the coating/substrate structure. The governing partial differential equations subjected to the complex thermal/mechanical boundary conditions are solved by the integral transform coupled with singular integral equations. A good agreement is achieved between the transient thermal stress intensity factors in the present work and steady-state values from previous literature. The influence of the thermal lags, nonhomogeneous parameters, and the thicknesses of two layers on the thermomechanical responses are investigated.