Development of back-face coatings for the characterization of non-reflective and opaque materials by laser shocks

• Characterization experiments on elastomers at high strain rates and high pressures. • Presentation of the overall approach for setting-up a laser shock test . • Three-layer sample design is proposed to determine the EOS of elastomer using VISAR . • Optimization of back-face coating thickness at 20 GPa shock pressure for measures. • Analysis of back-face coating influence on specimen behavior using FE simulations . The present study intends to make possible the dynamic characterization of a non-reflective and opaque material using a laser shock test which must lead to the establishment of an equation of state and a constitutive law. The instrumentation used is a back-face velocity measurement by a green laser interferometry (VISAR). In this study, a metallic coating (aluminum) is added to the back-face of the non-reflective material to be characterized (here an elastomer). The influence of the back-face coating thickness on material characterization is studied experimentally and numerically. The experimental results indicate that, whatever the thickness of the metal coating, it is possible to determine the equation of state of the material using a simulation model. Limitations of the proposed protocol are then finally discussed to get a constitutive law at loading up to 20 GPa. The role of a probable early damaging at the back-face of the sample and improvements proposals are given through numerical analysis of the shock tests.