Force and torque evaluation in hybrid FEM-MOM formulations

A method for the evaluation of forces and torque in static and quasistatic problems solved by adopting hybrid formulations is presented. The examined formulations are based on the use of the equivalence theorem that allows the definition of interior and exterior problems that are coupled by the continuity interface conditions. On the surfaces where the continuity conditions are imposed equivalent sources are present. These equivalent sources produce the same fields and potentials outside the fictitious surfaces as the enclosed body does. Resultant forces and torque acting on the bodies enclosed by each surface are evaluated by using these fictitious sources. Results obtained by the proposed method applied to magnetostatic and eddy current problems are compared in terms of accuracy and CPU time with results obtained by other methods and, where available, by experimental set up.