Ultrafast thermoelasticity for short-pulse laser heating

Abstract

Thermoelastic stress waves in a solid medium caused by subpicosecond-pulse laser heating are investigated with three different approaches: ultrafast thermoelasticity, Lord–Shulman theory, and the classical thermoelasticity. Both the conditions of uniaxial strain and uniaxial stress are considered. A combined finite difference/finite element algorithm is developed for solving the coupled, nonlinear, transient differential equations. It is shown that the thermomechanical results obtained from the ultrafast thermoelasticity are significantly different from those obtained from Lord–Shulman theory and the classical thermoelasticity. The other finding is that in contrast to long pulse and continuous-wave laser heating, thermal stresses in a free-expansion medium induced by an ultrashort, uniform volumetric heat source could be pronounced.