Finite element modelling of magnetic compression using coupled electromagnetic-structural codes

A link between the electromagnetic code, MEGA, and the structural code, DYNA3D has been developed. Although the primary use of this is for modelling of railgun components, it has previously been applied to a small experimental coilgun at Bath. The performance of coilguns is very dependent on projectile material conductivity, and so high purity aluminium was investigated. However, due to its low strength, it is crushed significantly by magnetic compression in the gun. Although impractical as a real projectile material, this provides useful benchmark experimental data on high strain rate plastic deformation caused by magnetic forces. This setup is equivalent to a large scale version of the classic jumping ring experiment, where the ring jumps with an acceleration of 40 kG.