Wave mode extraction from multimodal wave signals in an orthotropic composite plate.

In this paper the post-processing procedure based on the mode orthogonality is applied to extract individual waveforms at a composite plate edge from multimodal signals. To obtain the amplitudes of individual modes, numerically predicted modal through-thickness stress and displacement field values are used in the orthogonality relation. The performance of the mode extraction technique is evaluated by processing signals obtained from Finite Element (FE) modeling and experimental measurements. The propagation of the overlapping wave packets of Lamb modes S0 and A0 is considered along the fiber direction and perpendicular to that direction. The required experimental two-dimensional displacement components at the plate edge are measured by 3D Scanning Laser Doppler Vibrometer (3D SLDV). It is demonstrated that S0 mode can be extracted very well from the signal but A0 mode with slightly poorer accordance with the original waveforms and numerical predictions.