Image reconstruction of subsurface damage in unidirectional fiber composite laminate by dynamic shear strain analysis of lamb wave- a numerical approach

Composite laminates (CL) widely used in various engineering applications due to their high strength-to-weight ratios. Defects could inadvertently be produced in those, either during the manufacturing process or in the course of normal service lifetime of the component. Damage detection drawn much more attention during the design, operation, maintenance and repair of equipment involving CL. Moreover, subsurface damage could be endangering for the structural integrity. The dynamic shear strain analysis is a damage identification technique dealing with the overlapping of incident wave with the scattered wave from the finite defect in a plate. This investigation presents an application of such technique to detect the subsurface defect in horizontally transverse isotropic (HTI) media focusing on unidirectional fiber CL. Several numerical experiments carried out considering the fiber direction of the plate. A0 mode of Lamb wave chosen over S0 mode due to its shorter wavelength and high sensitivity to identify subsurface damage. The analytical data of outof-surface displacement obtained by using the multiphysics simulation software package LS-DYNA. The defect detection algorithm is based on the recorded time series signals of the orthogonal pair of out-of-surface shear strains. The numerical simulated result of the algorithm is presented in the form of image of the shape of the defect.