Size effect on heat conduction and associate thermal fracture behavior of thin ceramic plates

Abstract

Thermal barrier materials used in gas-turbine engines and aerospace vehicles have to resist large thermal gradients or high heat fluxes. The existence of high temperature gradient results in nonlocal effect of heat conduction, especially in very small time and space scale, the size effect of heat conduction is significant. In this work, a nonlocal dual-phase-lag heat conduction model is adopted to analyze the thermal shock fracture problem of thin cracked plates under sudden thermal shock. By using Laplace transform and inverse transform, the temperature field and the thermal stress field are obtained first. Then through the principle of superposition, the formulation results in a mode I crack problem. In the numerical part, the effects of different heat conduction models, thermal nonlocal parameters, and crack geometry parameters on the transient responses are discussed. By comparison analysis, the results show that taking the size effect into account is crucial in the assessment of thermal shock fracture of ceramic plates at micro/nano scale. The stress intensity factor first increases and then decreases with the increase of crack geometry parameters, indicating that the cracked plate exhibits crack growth resistance behaviour.