Analysis of startup behavior in a "C-shaped" armature using linked EMAP3D/DYNA3D finite element codes

An important consideration in the design of solid armatures is whether they maintain good solid-on-solid sliding contact during the initial portion of a launch, when the magnetic pressure is too low to provide sufficient load ing of the contact faces. This paper analyzes the complete electrical/struc tural startup behavior of a "C-shaped" armature in the 40-mm, square bore, laboratory launcher at the WT, using a pair of linked 3D finite element cod es. A first analysis solves for the electromagnetic loading on conductors u sing the EM code EMAP3D. A second analysis uses the hydrocode DYNA3D to sol ve the dynamic response of the armature, rails, insulators, and railgun con tainment using the results from EMAP3D as forcing functions. Peak displacem ents transverse to the direction of motion are found to be on the order of 0.1 mm.