A Method to Add High Speed Sliding Contact Boundary Conditions into Moving Electromagnetic Field by Lagrange Multiplier Method

Abstract

In the simulation of electromagnetic field in transient motion of electromagnetic railgun, we can use A, Φ-A method combining with Lagrange moving coordinate system method to calculate moving electromagnetic field. However, there will be accumulated errors on the high speed sliding contact surface by moving coordinate system method. And the high speed sliding contact boundary conditions should be applied to the electromagnetic field eliminate the errors. In the FEM(finite element model), apply the high speed sliding contact boundary conditions is complex. So we using the Lagrange multiplier method to add high speed sliding contact boundary conditions into FEM, that the large sparse matrix is easier to compute. The result of electromagnetic field, current density and electromagnetic have good characteristics of moving electromagnetic field. It shows that the calculation model in this paper has high accuracy.