Energy Conversion and Entropy Change During the Thermoelastic Effect

In this paper, the first and second laws of thermodynamics are applied in the coupled thermal and elastic fields to analyze the energy conversion and entropy change during the thermoelastic effect. The underlying physical mechanism for energy conversion is explained and the specific term which is responsible for energy conversion between the two coupled fields is also identified. As a result, governing equations which directly satisfy the law of conservation of energy are determined for both the elastic and thermal fields. Moreover, variation of the total entropy during the thermoelastic effect is also analyzed. Both contributions to the entropy change at the surface and within the bulk of the system are obtained with straightforward physical contents. In the end, a preliminary discussion on the thermoelastic effect under thermal shock is also presented; governing equations for both fields are also obtained with that for the thermal field being a wave-type equation.