Importance of the S1 symmetric Lamb wave in high frequency-scattering from spherical shells

摘要

Abstract: In the investigation of the scattering of high frequency waves from spherical shells it has been observed that it is possible to excite very large return signals at frequencies for which the integral/half integral wavelengths (due to the shear/dilatational wave of the material) are equal to the shell thickness. The large returns are shown to be attributable to resonance effects associated with the S$-1$/ symmetric Lamb wave, the upper limit of the resonance being predicted by the flat plate limit of the shell thickness. Following a brief sketch of the pertinent types of elastic waves, the role of the S$-1$/ symmetric Lamb wave in producing these large return signals is demonstrated using partial wave analysis.!12