Identification of subsurface delaminations in composite laminates

A novel procedure for the identification of delaminations in composite laminated panels from surface displacement measurements is presented in this paper. The damage identification procedure is formulated as an inverse problem where experimental data from digital speckle pattern interferometry (DSPI) out-of-plane displacement measurements, are used to quantify the planar location, size, orientation and depth of the flaw. The inverse problem is then reduced to an optimization problem where the optimum crack parameters are found by minimizing the objective function through the use of a real-coded low-population genetic algorithm. DSPI measurements of ten delaminated T700/LTM-45EL carbon/epoxy laminate panels are used to validate the methodology presented in this paper.