Experimental and Numerical Investigations of Vibrations at a Railgun with Discrete Supports

Within the French-German Research Institute of Saint-Louis (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. However, 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 (noncontact) method. However, this sensor turned out to be nonsuitable 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, in further experimental investigations, accelerometers were used, and the first experimental results were reported. Finally, the validity of the experimental results was proven by comparing with numerical calculations based on the 1-D and the 3-D models.