Simulation of mechanical relays under coupled electromagnetic physics and structural dynamics

Abstract

The function of mechanical relays depends largely on the mechanics and electromagnetics. Both can be calculated separately using finite element analysis (FEA). In this specific application, the electromagnetic field, which is induced by a coil in the relay, generates forces in the component that lead to deformations in the geometry, which, in turn, influences the electromagnetic forces in the relay. The aim of this simulation is to couple both physics so that the mechanics and electromagnetics can be calculated in a combined model. For this purpose, the properties for mechanical deformations and magnetic fields are simulated with the software Comsol Multiphysics. The electromagnetic forces are calculated in the electromagnetic model and coupled into the structure in the mechanical model using Maxwell’s surface tension tensor. The relay is operated by a voltage fed into the coil and is reset via a spring at the upper end of the relay. In this way, a work cycle of the relay can be simulated. The calculation can be used to determine the electromagnetic forces necessary to trigger the relay. Structural dynamic calculations in the electromagnetic field are possible, and the magnetic flux density in the corresponding areas can be optimised. Furthermore, interfering stray fields in the course of deformation can be determined, and the properties of the coil and the iron core can be optimised. This way, the function of a mechanical relay can be significantly improved.