Correlative Equations of Thermal Stress in Ceramic Disk Heated with Constant Heat Flux

Abstract

In the thermal shock test by means of a heated ceramic disk specimen with constant heat flux, temperature distributions in the specimen and time to fracture can be easily measured. Therefore, thermal stress in the ceramics can be estimated without measuring the heat transfer coefficient whose measurement is needed in case of water quenching test. On the other hand, the temperature dependence of thermal properties of material substantially affects the temperature distribution and thermal stress history. In this paper, numerical calculations of non-steady-state temperature distribution in thin disk, which was heated from outside with constant heat flux, were conducted to estimate the generated thermal stress. Temperature dependence of thermal conductivity and thermal diffusivity was assumed to be exponential functions. Time-dependent thermal stress was expressed with the correlative equations containing coefficients of temperature dependence of thermal properties, the supplied heat flux and Fourier's number. The last factor was a nondimensional parameter with specimen size and time. Based on the proposed equations, the effect of temperature dependence of thermal properties on thermal stress and the suitable experimental conditions in above-mentioned thermal shock test were discussed.