Surface-breaking crack gauging with the use of laser-generated Rayleigh waves

This paper studies crack depth gauging using wideband Rayleigh waves generated by laser in the thermoelastic regime. A finite element method (FEM) is used to calculate the scattering of the Rayleigh waves. The reflected and transmitted Rayleigh waves have different propagation paths and have very different frequency spectra. The arrival times of these scattered waves are crack depth related and can be used for crack depth gauging. Experimental measurements agree well with FEM predictions and validate the usefulness of the crack depth gauging method. (c) 2006 American Institute of Physics