Dynamic Response of an Electromagnetic Launcher Accelerating a C-Shaped Armature

Abstract

A C-shaped armature in an electromagnetic launcher creates the magnetic pressure on the rear surface of the armature. The transverse component of the magnetic pressure plays a main role to maintain the moving contact between the rails and the armature. It is larger than the repulsive pressure acting against the rails far away from the armature. It might cause the dynamic deflection to be amplified along the entire length of the rails, resulting in the magnification of the contact pressure when the elastic waves of the rails pass through the contact surface. In this paper the dynamic system is modeled as a Timoshenko beam on an elastic foundation subjected to an accelerating pressure combined with the repulsive pressure and the transverse component of the magnetic pressure. The spatial and time history of the accelerating pressure as an applied force of the governing equation is calculated using the experimental current and armature position in the launcher. The influence of the magnetic pressure on the rail deflection is described in point of propagation of the elastic waves. The dynamic deflections at different positions on the rail are compared to show that the dynamic behavior of the rail is strongly affected by the moving velocity of the armature.