Entropy Generation Rate During Laser Short Pulse Heating: Contribution of Heat Transfer and Thermal Stress
H. Al-Qahtani and B.S. Yilbas
Laser short-pulse heating of steel substrate is considered and entropy generation rate due to heat transfer and thermal stress development is examined. Cattaneo heat equation is incorporated to account for the hyperbolic behaviour of temperature field in the laser irradiated region. The closed form solution for temperature and thermal stress fields are obtained using the Laplace transformation method. The volumetric heat source is incorporated to account for the absorption of the incident laser beam. It is found that the maximum temperature gradient moves away from the surface with progressing time. Thermal stress developed is tensile in the surface region due to free expansion of the surface and it becomes compressive as the depth below the surface increases.
Keywords: Laser, short-pulse, thermal stress, entropy, Cattaneo heat equation, Laplace transformation