Current maldistribution in mid-riding integrated launch packages

Body forces accelerate launch packages in railguns. The body forces are the result of the interaction of the current and magnetic field. Nonuniform current distribution in a metallic armature launch package leads to nonuniform force distribution. Launch packages must be designed to handle these nonuniform distributions. Integrated launch packages designed to separate from a projectile are generally made from at least two pieces. Uneven current split between the two halves causes the acceleration forces in one half to be larger than the other and leads to a bending moment that may not have been integrated in the design. This bending moment leads to large bending and shear stresses that can exceed the capability of the launch package and lead to a failure. In this paper, the authors show that current maldistribution was the cause of a launch package failure in the Sabot Launched Electric Kinetic Energy (SLEKE) Program. Analysis of the launch package shows that a 5 percent current maldistribution can lead to stresses well above the capability of the launch package. In this paper, the authors describe the current maldistribution, its causes, and effects on the launch package and report experimental results in which the current distribution between the two halves was measured in-situ in a 90 mm railgun.<
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