Inversion of leaky Lamb wave data by simplex algorithm

Abstract

A numerical procedure is presented for the inversion of leaky Lamb wave (LLW) data to determine certain material properties of a waveguide, using a modified version of the simplex algorithm. The technique is capable of computing the parameter values that best fit a particular set of data, given an analytical model of the associated phenomenon containing any number of variables and parameters. The basic theoretical concepts involved are reviewed, and the versatility and simplicity of the method are illustrated by examples. The inversion scheme is used to estimate the elastic properties and thickness of an adhesive layer between two aluminum plates and the elastic constants of a unidirectional graphite/epoxy composite laminate. The limitations of the LLW data in the determination of the elastic constants of a composite are discussed.