Laser-generated ultrasound applied to two-layered materials characterization : semi-analytical model and experimental validation

This paper presents a new and original model of laser ultrasonics, adapted to structures made of two homogeneous and orthotropic layers (painted metals, composites, etc.). The cylindrical symmetry of the model allows fast calculation and observation of the displacements over a long duration. The simulations are compared with the experimental results performed with a Nd:Yag laser generation and a heterodyne interferometer. Applied to NDT, this model is used to optimize the choice of a paint covering a metallic plate in order to improve the detection of defects such as the effects due to corrosion.