Numerical analysis of the response of thick wires to extreme dynamic electro-mechanical loads

Research at Fraunhofer EMI addresses the response of materials in extreme dynamic loads. Besides mechanical or thermal loads, intense electric pulse currents also represent an extreme dynamic load. Experimentally, metallic samples, mainly thick wires, were electro-mechanically loaded with currents up to 400 kA. For this purpose, a test rig containing a high-voltage pulsed power supply and high-performance switches was built. Experiments comparing the response of copper, aluminum and tungsten wires are described in [1]. In this paper, we present an approach for the modelling of the response of thick (metallic) wires to extreme electro-mechanical loads. For this purpose, the essential electrodynamics, thermodynamic and mechanical aspects are being extracted and a way to couple the interrelated phenomena is suggested, allowing for the use of FEM simulation to determine the material response. Simulations are able to describe the time-dependent process of the multi-physics response for thick wires. The focus here is on the structural mechanical behavior including bending or buckling before the onset of the wire explosion. The new simulation approach is able to capture the basic experimental observations.