Guided waves are widely utilized in the fields of nondestructive testing and geophysical inversion, to estimate the medium properties through inversion of the dispersion curves. In this talk, we present improved methodologies for computing both dispersion curves and their derivatives, the two main ingredients of guided wave inversion. Specifically, a novel discretization approach based on Pade Approximants, named complex-length finite element method (CFEM), is developed for the computation of dispersion curves, which requires much fewer elements than existing methods. Similarly, a perturbation approach is developed to compute the derivatives of the dispersion curves without resorting to finite difference approximation, leading to better accuracy and efficiency. Through synthetic and real-life inversion examples, we illustrate that these algorithms result in more accurate estimates of the medium characteristics than the traditional methods, at a small fraction of computational effort.

[Joint work with Ali Vaziri Astaneh and Vladimir Druskin]