Analysis of Rail Erosion Damage During Electromagnetic Launch

Abstract

In the process of launching the electromagnetic rail guns (EMRGs), the erosion damage to the rail surface is mainly caused by the joule heat generated by the rail body resistance and armature-rail contact resistance as the current runs through the rail. According to the joule heat and the law of conservation of energy, this paper develops a formula to calculate the temperature rise of rail surface, proposes the method of using temperature rise of rail surface for representing rail erosion damage, and the mathematical formula indicates the relevance between the temperature rise of rail surface and current, linear current density, armature moving speed, rail material, state of armature-rail contact, and skin effect. Dynamic test data required for calculation of rail current, muzzle voltage, armature bore displacement, and velocity are obtained through launching tests, and are used to calculate the surface temperature rise of rails of different materials during the launch of EMRGs. The calculation produces the temperature rise of rails at any positions along the length direction. The results are compared with the photographs of rail surface after the launch, and the analysis verifies the feasibility of representing rail erosion damage with temperature rise of rail surface.