Research on the Transition Mechanism in Rail Gun Based on the Ultrahigh Speed Oblique Impact Collision Calculation Model

During the high-speed motion phase of the armature in an electromagnetic rail launcher, the impact load may cause collision vibration between the armature’s tail and the rail, leading to a loss of contact between the armature and rail. This, in turn, can generate a transition arc, affecting the launch performance of the armature. This article establishes a dynamic calculation model of ultrahigh speed oblique impact for the armature/rail (A/R) interface based on the Johnson–Cook nonlinear constitutive model of materials. The model considers the strong coupling relationship between strain, strain rate, and pressure of the A/R materials. Based on this calculation model, the dynamic response of the armature structure during the oblique impact collision and the change in contact status between the armature and rail are studied. The critical conditions for the loss of contact at the A/R interface are analyzed, a new transition mechanism at the current falling edge is proposed, and the critical magnetic pressure and critical current line density corresponding to the transition under different impact angles and armature motion speeds are given. The findings of this article can help reduce the occurrence of transition phenomena during the electromagnetic launch process.