Measurement of High-Strain-Rate Adiabatic Strength of Conductors

The current-carrying conductors in electromagnetic launchers and rotating machines are exposed to high stress and thermal loads that last for a few milliseconds, with temperatures ranging up to the melting point of the materials. Even though equilibrium behavior of materials at high temperature is well characterized, nonequilibrium, short-duration behavior is not well understood. Properties for short-duration exposure to high temperatures (a quasi-adiabatic process) are crucial to understanding the transient physics of railgun components, since use of equilibrium (isothermal) properties would entail compromise in evaluation of stress and strain fields. These errors can grow when considering multiple applied pulses, as in cycle life evaluation . In this paper, we describe an experiment that will help characterize such properties near railgun operating conditions. We present preliminary data obtained for copper