Electro-magnetic collapse of thick-walled cylinders to investigate spontaneous shear localization

We present an electro-magnetic (EM) setup in order to collapse thick-walled cylinders, for the investigation of spontaneous formation of multiple adiabatic shear bands. The EM setup is based on a pulsed current generator using a capacitor bank system. The cylindrical specimen is part of an assembly of coaxial cylinders, where the inner and outer cylinders, each attached to an opposite pole, are short-circuited. Upon capacitor discharge, a high current flows through the cylinders, in opposite directions, creating repulsive magnetic forces between them. The outer cylinder is driven outwards and the inner cylinder is driven inwards - in a collapsing manner. This work presents the design procedure of the specimens’ geometry using numerical simulations, and some preliminary experimental results for SS304L steel specimens. The spatial distribution of the multiple adiabatic shear bands in these specimens is in good agreement with that reported in the literature for explosively driven experiments with the same material. Our numerical simulations of the collapsing cylinder show good agreement with the experimental results for both global behavior and shear band distribution.