Thermal Stress Analysis of the Rails and the Armature of an Electromagnetic Launcher

In an electromagnetic launcher (EML), the magnetic field creates a dynamic force that moves the armature forward. During launch, electrical current creates high body forces and temperature distribution in the rails and the armature. As a result, the rails and armature experience high amplitude stress and strain, which damage the rails and the armature and reduce their life span. The purpose of this paper is to investigate the effect of body force, as well as the temperature distribution on the displacement of the rails in an EML. In this paper, the physical and geometrical properties of the rails are constant in location. In our formulation of governing nonlinear differential equations, Maxwell, energy, and Navier equations are applied to the rails under dynamic loading. To solve the nonlinear governing differential equations, a finite difference base code is developed and utilized. It is shown that the maximum volumetric forces take place where the highest magnetic field gradient occurs. In addition, the maximum magnetic force is accumulated at the trailing edge of the armature and portions of the rail interior. The thermal stress distribution follows the same trend as the displacement due to the temperature behavior of the rails.