<title>Modal decomposition of double-mode Lamb waves: numerical verification and discussion on extension to general multimode leaky Lamb waves</title>

Abstract

This research proposes a technique to decompose a transient, multi-mode, Lamb wave, time-domain signal into its individual Lamb wave modes. The technique is derived for a Lamb wave signal consisting of two Lamb wave modes (double-mode Lamb wave signal). The extension to the general multi-mode signal is straightforward, but requires additional computations. The proposed technique assumes knowledge of the dispersion characteristics of Lamb waves, which can be theoretically calculated or obtained by other signal processing techniques. The proposed technique is verified for simulated (by eigen-expansion) signals to demonstrate the method's accuracy in a well-controlled environment. The use of eigen-expansion signals for the simulation allows for the calculation of the total response, as a combination of responses due to all existing Lamb modes. The comparison between the decomposed and simulated signals shows good agreement and demonstrates the validity of the proposed technique. The paper concludes with a discussion of the extension of this technique to the more general multimode, Lamb wave signal in leaky conditions, and its use in attenuation calculations.