ELECTROMAGNETIC LAUNCHER ACCELERATES REACTIVE MATERIALS

Reactive materials (RM) are inert under ambient conditions, but release considerable amounts of energy when subjected to appropriate stimuli, such as the large stresses that occur during an impact. While the expression RM covers a broad range of materials, there are components which show similar structural integrity as steel and are called reactive structural materials (RSM). The RSM enhanced warheads function by detonating and accelerating their shrapnel or preformed fragments. The RSM fragments impact a secondary target, and in addition to their kinetic energy, the fragments release chemical energy upon impact, such as heat T and pressure p. This chemical energy release is often referred to as impact induced energy release (IIER). With comparable density and mechanical properties to conventional fragmentation materials, using RSM results in an increased power density. In order to understand and quantify the IIER, high velocity impact (HVI) tests are performed were RSM are launched against defined targets. The RSM are fragments of cylindrical shape with a diameter D=5 mm and a length L=5 mm made of ferrocerium. This study demonstrates the advantage of employing the electromagnetic (EM) launcher, also known as rail gun to accelerate RSM. The EM launcher uses the Lorentz force for the acceleration as the acceleration profile can be defined by shaping the timedependent current accordingly. In this study, the RSM projectiles should reach a certain vi when varying acceleration profiles are applied in order to investigate the dependence of the way of acceleration on the IIER. We present the first results of a cylindrical RSM fragment, made of the brittle ferrocerium material, impacting a t=2 mm aluminium plate in a pressure vessel. The IIER is measured by the pressure increase inside the confined volume to measure, how the different acceleration profiles have an influence on the energy release, even if the RSM kinetic energy is constant. The aim of this project is to test characterisation methods for the acceleration of RSM, and to investigate if the acceleration has an influence on the RSM’s energy release.