Thermal and mechanical finite element modeling of laser-generated ultrasound in coating–substrate system

Thermal and mechanical finite element modeling of laser-generated ultrasound in coating–substrate system is presented, which entails a numerical formulation for the transient responses in terms of the characteristics of the source that originated the waves in the thermoelastic regime. The formulation takes into account the temperature dependence of the material parameters and thermal diffusion from the source. Numerical results show that the temperature gradient field is equivalent to the body force source, namely, vertical forces propagate downward and horizontal forces outward in the specimen. Waveforms at the epicenter present fast oscillations immediately after the precursor, which are produced by multiple reflections of the longitudinal in the coating, the thickness of the coating has remarkable influence on the waveforms at the epicenter.