Analysis of the zero-crossing technique in relation to measurements of phase velocities of the S0 mode of Lamb waves

Abstract

It was demonstrated by previous works that the regularities obtained in phased velocity measurement of A₀ mode of Lamb waves using zero-crossing technique creates possibilities for identification of the modes. The objective of the work presented was to investigate the similar approach on the S_o mode of Lamb waves and to determines if difference of regularities is sufficient or strong enough to be used for mode identification. The signals obtained by finite element modelling of S₀ mode in 2mm thickness aluminium plate were analysed. The excitation signal was 300 kHz burst with the Gaussian envelop It was demonstrated that the distribution of lower and higher frequency components in the signals are different for A₀ and S₀ modes, what can be exploited as criteria for mode identification