The use of coupled EM-hydro finite element techniques for the design of railguns

The primary goal of the electric launcher modelling team is to develop techniques to aid our understanding of the physics of railgun launch. This is essential in order to combat the problems which will degrade the performance of railguns from their theoretical limits, especially with the Kirkcudbright facility in mind. In particular, we need to understand die transient material response caused by the launch process. Plasma transitioning and nonideal contact between armature and rail are just two of the problems that analysis codes must be able to address. This paper shows the results of finite element (FE) simulations, at 90 mm scale, of the armature-barrel interaction. Special emphasis is put on the resolution and validation of high temperature hot spots in the armature and in the prediction of transient barrel response. The FE method is based on a soft linking of the 3D FE transient electrical-thermal code MEGA to the dynamic structural code DYNA3D. This version of the MEGA-DYNA3D link has a multi-slide line capability which allows stressing to be calculated by taking into account the hydrodynamic effects of the rail-armature interaction as well as the electromagnetic forces.<>