Role of Thermal Expansion in Thermal Stress Resistance of Semi-Absorbing Brittle Materials Subjected to Severe Thermal Radiation
An analysis is presented of the thermal stresses resulting from “thermal trapping” in semi-absorbing brittle ceramic materials in the form of a thin flat plate subjected to intense thermal radiation. Solutions for the thermal stresses are presented for symmetric and asymmetric radiation heating and convective cooling with limiting values of the heat transfer coefficient, h = 0 and ∞. For h = ∞, the stresses are identically equal to zero for values of the optical thickness pa of 0 and ∞, and reach their maximum value at μa ≃ 1.3 and 2.0 for symmetric and asymmetric heating respectively. For h = 0, the magnitude of thermal stress increases with increasing optical thickness.
Expressions are derived for the maximum radiation heat flux to which the plate can be subjected without failure, in terms of the pertinent material properties. These properties are combined in “figures-of-merit” for the selection of material with the optimum thermal stress resistance, appropriate for given heating and cooling conditions. These figures-of-merit, which may contain as many as seven material properties, indicate the high thermal stress resistance requires low values of the coefficient of thermal expansion, Young’s modulus, Poisson’s ratio, emissivity, and the absorption coefficient in combination with high values of tensile strength and thermal conductivity.
KeywordsHeat Transfer Coefficient Thermal Stress Brittle Material Optical Thickness Radiation Heat Flux
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- 5.D. P. H. Hasselman, J. R. Thomas, Jr., M. P. Kamat and K. Satyamurthy, J. Amer. Ceram. Soc., 63 (1980) 21.Google Scholar
- 6.J. R. Thomas, Jr., J. P. Singh and D. P. H. Hasselman, J. Amer. Ceram. Soc. (in press).Google Scholar
- 7.H. S. Carslaw and J. C. Jaeger, Conduction of Heat in Solids, Oxford at the Clarendon Press (1960).Google Scholar
- 8.B. Boley and J. Wiener, Theory of Thermal Stresses, John Wiley and Sons, New York (1960).Google Scholar