Theoretical and experimental investigation of surface acoustic wave propagation on a hollow spherical shell using laser ultrasound

Abstract

An analytical model of surface acoustic waves on the surface of a hollow spherical shell generated by a pulsed laser source is proposed using the Legendre polynomials expansion and contour integration method. The model predicts two interesting phenomena. The dispersive characteristic of thick spherical shells is mainly determined by the spherical Rayleigh waves, but the corresponding characteristic of thin spherical shells is dominated by zero-order anti-symmetric plate waves; The hollow spherical spheres with the same ratio of thickness to radius have the same dispersive characteristic. Using laser ultrasound technique, the proposed model is confirmed experimentally on a hollow polymer sphere of mm-sized diameter.