Experimental and numerical investigations of vibrations at a railgun with discrete supports

Within the ISL railgun design, discrete supports in the form of steel bolts uniformly distributed along the length of the railgun counteract the repelling magnetic forces acting on the rails. In the past, numerical simulations on the structural mechanics of these setups have been performed. A significant rail displacement was calculated. Yet, the establishment of the displacement amplitude during an experiment is the final goal. The first task to manage in this respect is the application of a sensor capable of sensing vertical rail displacements. Experimental investigations started at the ISL at a short circuited railgun employing an optical (non contact) method. However, this sensor turned out not to be suitable for the job due to its lack of a preferred axis. This became clear when comparative measurements with an accelerometer (a single axis measurement device) were carried out. Consequently, our experimental investigations continued employing accelerometers and first experimental results are reported. These results were in turn confirmed by numerical calculations basing on a 1D model of the system.