Mechanical, Electrical, and Thermal Coupled-Field Simulation of a Molten Metal Bridge During Contact Separation

The purpose of this paper is to present a numerical simulation of the behavior of a molten metal bridge during contact separation. Sequential coupling allows for studying the interactions between mechanical, electrical, and thermal phenomena occurring under a low current flow (between 5 and 25 A). The 2-D axisymmetric geometry model considers a sphere pressed on a plane. The model takes into account the temperature dependence of material properties. Contact resistance, separation acceleration, and current rate are obtained by experiments and are also applied to the model. The structural deformations and the voltage and temperature distributions are calculated with the help of the finite element method. Results show that the time is less than 30 μs from the separation of contact to the generation of a molten metal bridge under current loads of 5-25 A; the index change relation is shown between temperature of central node and separation time; the current density has a nonuniform distribution along the section of a molten metal bridge; whatever be the initial loads, melting and vaporizing voltages of a molten metal bridge are, respectively, 0.38 and 0.66 V, which are basically consistent with the literature.