Lamb wave propagation in a plate with a finite width

Abstract

Using a low frequency range in long-range inspection of a plate with Lamb waves, directivity of Lamb waves becomes weak and Lamb wave propagation is affected by the both sides of a plate. Thus, dispersion curves for a plate with a finite width should be used in nondestructive testing for it. Since dispersion curves for a plate with a finite width cannot be analytically obtained, guided wave calculation technique developed by authors using a semi-analytical finite element method is useful. In this study, therefore, theoretical dispersion curves for a plate with a finite width were derived using the calculation technique, and the characteristic of dispersion curves and the relationship between dispersion curves and vibration distributions were described. And also, the theoretical dispersion curves and vibration distributions obtained by the calculation were verified by experiments in which vibration distributions were obtained by measuring waveforms at many points with a laser interferometer.