Dynamic shear-strain analysis of A0 mode Lamb wave field in composite materials with through holes

This paper proposes a novel imaging method, which estimates the elasticity in the region of interest having somewhat inhomogeneity contrasted to the surrounding area. The proposed imaging methodology is summarized as follows: 1) The distributions of the normal displacement of the object surface is governed by the 2-dimensional wave equation in the Lamb wave field. 2) When the single propagating wave front exists on the surface of the object with no defect, the orthogonal pair of the out-of-surface shear strains are linearly dependent each other. Consequently the determinant of a covariance matrix, which is composed of the orthogonal pair of the shear strains, becomes zero. 3) When a region of interest having somewhat inhomogeneity exists, scattered wave arises in the guided wave field. The determinant becomes, therefore, larger than zero because of the independency between the orthogonal pair over the region of the scattered and incident wave field.