Measurement of the group velocity of Lamb waves in aluminium plate using spectrum decomposition technique

Abstract

In the previous our article the technique for measurement of the group velocity using spectrum decomposition was proposed and demonstrated on the signals obtained from the finite element modelling. The objective of this work is to check this technique using experimental signals. The experiments were carried out on the 2mm thickness aluminium plate with dimensions 1100mm x 620mm. The guided waves were generated using a wide band contact type transducer. The excitation signal was 300 kHz, 3 periods burst with the Gaussian envelop. The signals were processed using the proposed spectrum decomposition algorithm and corresponding segments of the group velocity dispersion curves of the A₀ and the S₀ modes of Lamb waves were obtained. The analysis demonstrated that scattering and errors of the results essentially depends on the bandwidth of the filter used for decomposition. So, it is necessary to select parameters of the filters separately for each mode under investigation. The obtain results were compared with the theoretical dispersions curve and good correspondence was obtained.

http://dx.doi.org/10.5755/j01.u.66.4.1026