The fragmentation of wires due to pulsed currents: influence of the skin effect

The phenomenon that wires may fragment in the solid state when subject to high pulsed currents has been observed in many experiments, but has yet to be fully explained. The experiments indicate that the wires break into two or more pieces due to a longitudinal tensile stress. The fractures occur successively, with the current being maintained by the formation of an arc between consecutive pieces of the wire. A previous theoretical study of this phenomenon was performed by S. Molokov and J.E. Allen (see J. Phys. D, Appl. Phys., vol.30, p.3131-41, 1997), who investigated the propagation of axisymmetric stress waves in a wire initiated both by thermal stresses due to Joule heating and also by the Lorentz force. Molokov and Allen solved the governing magneto-thermo-elastic equations for a uniform current density with zero risetime. In this paper we extend Molokov and Allen´s study by including the skin effect, that is by allowing for the diffusion of current across the wire, and by considering the effect of nonzero current risetime