SOME ASPECTS OF MAGNETIC FORCE COMPUTATION USING BEM-FEM COUPLING

Abstract

For the calculation of magnetic forces with the Maxwell stress tensor the normal and the tangential derivatives of the vector potential A have to be known. We choose Co-continuous elements, therefore A and its tangential derivatives are continuous. In contrast, the normal derivative A/ n calculated with the finite element method is continuous only in a weak sense. When BEM-FEM coupling is used however, the value of A/ n is uniquely available on the coupling surfaces from the BEM formulation. Two methods of magnetic force computation using A/ n either from FEM or from BEM data will be presented. Their accuracy will be compared by means of several examples. [Vol. 12, No. 2 (1997), pp Special Issue on Numerical Field Calculations in Electrical Engineering, 117-120]