Degradation Characteristics of Electrical Treeing in Glass Fiber-Reinforced Epoxy Under Mechanical Loading

The epoxy resin/glass fiber composite pull rod serves as a critical structural element in gas-insulated switchgear (GIS), functioning as the transmission component during opening and closing operations. The insulating properties of the pull rod play a vital role in ensuring the stable operation of the switchgear. This study explores the insulation failure behavior of epoxy resin/glass fiber composites subjected to electric fields combined with compressive-tensile mechanical loading, through both experimental testing and numerical simulation. The findings indicate that mechanical loading involving alternating compression and tension increases the breakdown probability and significantly shortens the average time to failure compared to pure compressive loading. Simulation results further reveal that interfacial stress concentrations between the resin matrix and reinforcing fibers intensify under alternating loads, leading to the formation of pronounced defects and degradation in the composite's dielectric integrity. These insights provide practical guidance for evaluating the insulation performance of pull rods used in GIS applications.