Finite element multi-physics modeling for ohmic contact of microswitches

The purpose of this paper is to investigate the thermoelectrical behaviour of ohmic microcontacts under low force. The temperature in the contact zone is very important for the reliability of microswitches. As it is very difficult to measure the inner temperature, the numerical thermal modelling of electrical contacts offers interesting perspectives. A multi-physics modelling of electrical contact is accomplished with the finite element commercial package ANSYS™. Two approaches for coupled-field analysis are investigated, namely direct and load transfer. The thermo-electro-mechanical modelling is firstly validated with a smooth sphere-plane contact, and then applied for a real rough contact computation, elastic-plastic material deformation is included in the modelling. The temperature distribution on the contact surface is plotted, and the maximum temperature is found around the asperities with the highest deformation. The multi-physics model offers a reliable method to investigate the steady-state thermal behaviour of electrical contact with rough surface included.

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