Modeling of Thermomechanical Processes in the Electrode Material of the Plasmatron

摘要

The associated thermoelasticity task including the equilibrium equations, the Cauchy relations and Hooke's law and the heat equation is used to study thermomechanical processes in an electrode under the action of an electric arc. The dynamics of the temperature and stressed states of the plasmatron electrode from the copper and tungsten was investigated and zones of possible brittle fracture of the material were identified. The obtained solutions showed that the high heating rates and rapid output to stationary mode characterize the electrode heating. The resistance of electrodes strongly depends on the thermophysical properties of the materials. It should be mentioned there is a sharp change in temperature along the electrode length in the area of the active zone (heating surface). An attribute of the temperature distribution are the considerable axial and radial temperature gradients, which can lead to the large thermal stresses in the electrode. The thermal action of the arc spot leads to alternating stress distribution in the wall thickness. The greatest danger is represented by the area of concentration of tensile normal stresses in the place of fixation, as well as near the core. Large thermal stresses can contribute to the formation of microcracks. The formation of cracks leads to the strong changes in the structure of the material and the distribution of the temperature in it and, as a consequence, to a decrease in the operability of the electrode.