Measurement of Acoustoelastic Coefficient with Leaky Surface Wave

Acoustoelastic stress measurement has been established for bulk shear wave, in particular with birefringence of the wave. This method, however, evaluates only average stress over thickness of a sample. Some preliminary studies have been reported for local surface stress measurement with Rayleigh or leaky Rayleigh wave. An approach using an acoustic microscope operated with burst waves over 100MHz [1, 2] is markedly sensitive to surface roughness and anisotropy of grains due to very short wave length of the wave. The other approach using contact transducers needs long propagation distance [3, 4]