Generation of thermoelastic stress waves by impulsive electromagnetic radiation.

The penetration and absorption of electromagnetic radiation through a thin layer adjacent to the surface of an elastic half-space provides a sudden heat source distribution through the layer, and, in consequence, stress waves are generated. A solution for uniaxial motion is given in the limit situation when the pulse duration approaches zero in comparison with the wave travel time over the absorption depth, together with the neglect of thermal diffusion on this time scale. The radiation absorption is assumed to decay exponentially with depth. These simplifying features lead to stress wave profiles which clearly illustrate the effective nature of the wave propagation, so that the present solution provides a useful complement to previously obtained solutions of a more general nature. In the case when the surface is stress-free, following initial build-up (here instantaneous) of compressive stress within the absorption layer, a tensile wave propagates outward from the layer. Numerical data are presented to show that the peak tensile stress can attain significant levels within distances of a few absorption depths.