Int J Fract (2011) 167:183–193 DOI 10.1007/s10704-010-9543-0 ORIGINAL PAPER Melting and crack growth in electrical conductors subjected to short-duration current pulses F. Gallo · S. Satapathy · K. Ravi-Chandar Received: 1 June 2010 / Accepted: 22 August 2010 / Published online: 13 October 2010 © Springer Science+Business Media B.V. 2010 Abstract In this paper, we examine the response of a crack tip in an electrically conducting material sub- jected to a combination of mechanical load as well as a high density electrical current. We present a detailed examination of the process of evolution of melting and ejection, as revealed by high speed photography. The critical mechanical and electrical parameters that govern crack extension are then determined for two different alloys. Finally, we present an evaluation of the phenomenon through a coupled field simulation to examine the nature of the interaction between the elec- tric field and the thermo-mechanical response. Keywords Joule heating · Current intensity factor · Electromechanical interaction 1 Introduction Electrical conductors subjected to high current den- sities sustain significant joule heating; when such Electronic supplementary material The online version of this article (doi:10.1007/s10704-010-9543-0) contains supplementary material, which is available to authorized users. F. Gallo · K. Ravi-Chandar (B ) Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712-0235, USA e-mail: fracture@mail.ae.utexas.edu S. Satapathy Institute for Advanced Technology, The University of Texas at Austin, Austin, Texas 78712-0235, USA conductors contain cracks or crack-like defects, and are also subjected to external mechanical loads, the combined effect could possibly result in extension of the crack and catastrophic failure of the struc- ture. Understanding the effect of electric current on mechanically loaded metallic conductors with notches or cracks is important in many applications; this is especially true in rail-guns where the durability of the rails is significantly influenced by cracks or notches. Other applications include microelectronic circuit lines with possible defects and other structures subjected to high current densities such as high-voltage power supplies, superconducting magnets and high-current devices, where the nominal current densities are likely to be on the order of 10 8 A/m 2 or greater. Lightning strikes on some structures could also generate local current densities of this order of magnitude. Exper- iments reported in the literature have demonstrated that the concentration of electromagnetic energy in the vicinity of a notch or crack can result in local- ized melting and ejection of the metal (Finkel et al. 1977; Doelp 1984; Satapathy et al. 2005; Gallo et al. 2009). While estimates of the stress fields, the electro- magnetic fields and temperature fields can be obtained, at least through numerical simulations, three essential ingredients are missing: (i) a proper understanding of the sequence of events to be simulated (since the over- all response appears to be a complex mix of mechan- ical deformation, electric field concentration, joule heating, heat conduction, melting and expulsion), (ii) appropriate constitutive description of the material that 123