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Dynamic Response and Critical Velocity of Rails in Electromagnetic Rail Launcher Due to Axial Force

The dynamic response and the critical velocity of the rails in electromagnetic rail launcher (EMRL) have a direct influence on launch accuracy and contact between the armature and the rail. In order to analyze the influence of the axial force on the dynamic response of the rails in EMRL during the launching process, the vibration control equation of the rail is established. The analytical solution and the critical velocity of the rail’s vibration under given initial and boundary conditions are derived through the method of separation of variables. On this basis, the influence of the preloaded axial force on the dynamic response and critical velocity of the rail under the typical current excitation and the armature constant velocity motion is analyzed, respectively, by the programming code. Studies have shown that the critical velocity increases with increasing axial force, but as the axial force gradually increases, the increasing trend of the critical velocity gradually becomes slower; the axial tensile force on the rail can suppress the vibration of the rail, especially when the armature velocity is close to the critical velocity; the influence range of the resonance region decreases with increasing axial force. The results can provide guidance for improving the critical velocity of the rail and reduce the amplitude of the vibration during the launch.