Modeling of the contact resistance and the heating of the contact of a multiple brush projectile for railguns with the final element code ANSYS

When metal fiber brush armatures are used in electromagnetic railguns, contact transition has to be avoided. Therefore we want to simulate the current and temperature distribution in a multiple brush projectile for an augmented railgun to determine the heat load at the contact between the brushes and the rails. For the simulations the finite element code ANSYS is used. This code allows a combination of an electromagnetic and a thermal analysis. In this paper the simulation model we used for the study of the heat load at the contact between the rails and the current brush is presented. The modeling of the contact resistance between the rails and the fiber brushes plays a key role in this model. To simulate this contact resistance, we adapted the resistivity in a thin layer between the rails and the fiber brushes. The thickness of this layer and the resistivity are the main parameters for the electromagnetic analysis. For the thermal analysis, the thermal conductivity plays a key role. The influence of these parameters is studied and the results are discussed in this paper.