Numerical Simulations of Laser-Driven Cratering Experiments into Porous Graphite

Abstract

We present the results of an experimental campaign conducted on the LULI2000 laser facility. Semi-infinite targets of a commercial grade of porous graphite were submitted to high-power laser irradiation inorder to generate craters. A 15 ns pulse duration was used along with a focal spot diameter of 900 µm to deliver energies up to 750 J. Numerical simulations of these shots have been performed following a specificmethodology which can be divided in three steps. Firstly, the mechanical loading induced by the laser iscalibrated by simulating the same shot on a thin aluminum target of which free surface velocity is measured byPDV and line-VISAR. Secondly, the same shot is performed on a thin graphite target to validate the materialmodel of graphite. Thirdly, the craterization shot on semi-infinite target is simulated. Numerical results arecompared to experimental measurements of craters obtained using an interferometric profilometer.

Numerical Simulations of Laser-Induced Shock Experiments on Graphite

“…Even though many of the hydrocodes are also able to describe the propagation of the wave generated from the plasma expansion and the free surface velocity profile, most of them are not able to simulate the fracture mechanisms inside the material and describe only 1D geometries. For this reason, one possible numerical approach is to simulate the laser energy deposition map with a specific radiation hydrocode and import this map into an explicit Finite Element Solver (FEM) with appropriate material models [35][36][37], such as Ansys Autodyn [38] or LS-DYNA [39].…”