Interface damage driven electrical degradation dynamics of glass fiber-reinforced epoxy composites

The damage of glass fiber-reinforced epoxy composites (GFRP) caused by mechanical loads is an important reason for the related electrical breakdown. In this paper, the L-shaped needle-wire electrode is used to simulate the coupling direction of mechanical stress and electric field, and the influences of equivalent tension and compression load on the electrical tree degradation of GFRP are obtained. It is found that both tensile and compressive loads will aggravate the electrical tree degradation in GFRP and reduce the average breakdown time. Under tensile load, the damage area of electrical tree increases, and even the sample breaks at the moment of electrical breakdown. However, the color of electrical tree channels is light and the number of branches is small under compression load. The narrow carbonization channels after breakdown will be accompanied by spherical damage areas. The simulation results of GFRP interface damage confirm that the increase of tension and compression load will lead to different degrees of damage at the fiber-matrix interface, and then cause local electric field distortion. At the same time, the combined action of high temperature and high pressure and external mechanical load will aggravate the electrical tree degradation process of GFRP.