Comparison of modelling and experimental results of the phase velocity measurement of Lamb wave in aluminium plate

Abstract

The analysis of the phase velocity measurement using zero-crossing technique presented in previous our articles revealed some regularities which can be exploited for mode identification in the complicated signals of guided waves. However the investigations were carried out using the signals obtained by a finite element method. The objective of the work presented is to carry out similar investigation using experimental signals and to determine is it possible to measure a needed parameter with accuracy sufficient for mode identification. The experiments were carried out on the 2mm thickness aluminium plate with dimensions 1100 mm x 620 mm. The guided waves were excited and recorded using the contact type wide band transducers. The waveform of the excited waves is the 300 kHz burst with Gaussian envelop. The receiver was scanned on the plate in the distance ranges 60-260 mm from the excitation point with the step 0.1 mm. The analysis has shown that scattering of results is almost three times bigger then in the case of the simulated signals. Comparison of the modelling and the experimental results also revealed some differences which partially can be explained by different excitation condition, however the experimental investigation proved main regularities obtained using simulated signals. So, in general the experimental investigation demonstrated the possibility of mode identification based of the phase velocity measurement using the zero-crossing technique.