Abstract
This paper presents the detection of surface crack in a woven fabric composite laminate using energy index method. A carbon fabric F3T-282⁄epoxy (DICY) is used to fabricate a plain woven laminate. In the first place, the unknown material properties can be obtained by employing inverse method through the finite element analysis. Three equivalent FE models, i.e. cross-ply [0⁄90]ns , orthotropic and representative cell models are established to simulate the woven laminate. Experimental modal analysis is performed to obtain the modal displacements of the laminate before and after damage. The modal displacements are used to compute the modal strain energies. A damage index is defined by using the fractional modal strain energy and used to identify the surface crack location. Limited by grid points of measurement, a differential quadrature method is applied to compute the partial differential terms in strain energy formula. Only few measured mode shapes are required in this approach. This method provides a flexible, cost effective, nondestructive, and feasible of real-time detection of potential damage in woven fabric composite laminates.
