Application of a two-layer semi-analytical model for the improvement of laser-ultrasonic generation

Abstract The new laser-based ultrasound model presented in this paper takes into account the layered structures generally encountered in aeronautic materials (painted metals, composites, lapped joints…) which are subjected to impacts, fatigue and corrosion. The structure is supposed to be a plate made of two layers of different materials. The sample presents a cylindrical orthotropy. Validations of the model are performed by comparing the results it provides with experimental measurements using a Nd:YAG pump laser and an interferometric detection. The symmetry of the model allows fast calculation and prediction of the displacements over a long time period. These advantages are used to study the improvement of the laser-ultrasonic generation, by varying the thickness of the first layer in the case of a NDT strippable paint layer covering a metal layer.