Development of a numerical code for laser-induced shock waves applications

The recent development of LAser Shock Adhesion Test (LASAT) as quantitative Non-Destructive Testing (NDT) process for evaluation of structural bonded assemblies brings new challenges. Applicative assemblies composed o f complex materials with poor transverse mechanical properties and highly resistant bonded joints require laser parameters optimization and a more accurate control on the whole process. The development of a numerical tool is then necessary to ensure laser parameters specification to evaluate the bond mechanical strength for a given assembly. In this document, the ability of ESTHER code for the description of laser-matter interaction on aluminum and ablation pressure prediction is exposed. The influence of the target initial reflectivity on ablation pressure is investigated. In this paper, validation o f the code in both direct (1 - 500 GW/cm(2)) and water-confined (0, 2 - 7 GW/cm(2)) irradiation regimes is achieved with comparison to suitable sets o f experimental data. Experiments were led on two laser facilities: the transportable laser shock generator (GCLT) at the CEA/DAM/DIF and the Hephaistos facility at the Processes and Engineering in Mechanics and Materials laboratory (PIMM lab). Numerical models developed in this work are compared to previous experimental data and to reference models. Ablation pressures defined by our predictive models can then be coupled to other codes which are able to describe 2D/3D shock propagation, in order to model the entire LASAT process on complex assemblies. Characterization of a 6061 Aluminum/ Epoxy/ 6061 Aluminum assembly is achieved using ESTHER, showing its ability to master the phenomena involved in the LASAT process. For the first time, results open the full numerical design of laser adhesion test with the same code.