A parameter estimation based sparse representation approach for mode separation and dispersion compensation of Lamb waves in isotropic plate

A response Lamb wave is usually a combination of dispersive wave packets corresponding to different modes, and the explicit dispersion curves are hard to acquire accurately sometimes. A parameter estimation based sparse representation approach is established to extract each pure single-mode component with dispersion removal from the dispersive multi-mode Lamb waves. The dispersion characteristic parameters of the Lamb modes are extracted from a response Lamb wave with a known propagation distance using a parameter estimation algorithm. A parametric dictionary is designed to sparsely decompose the dispersive multi-mode Lamb waves, and those parameters used for constructing the dictionary are extracted from a response signal based on a Lamb wave propagation model. In the process of reconstructing each mode component, the original dictionary is replaced with a multi-mode and non-dispersive dictionary so that the dispersion effect can be removed. Results from simulations and experiments both verify the effectiveness of the proposed approach.