Stress Concentration Effect in Interface Between Conductor and Epoxy Resin in Coaxial Components of Power Equipment

The spacer used in gas insulated switchgear (GIS) plays a vital role in its safe operation. The mismatch of mechanical properties between conductor and insulating material in spacers results in stress concentration at the interface between them. During a hydrostatic test, mechanical damages are often initiated from the interface. In this paper, the stress between aluminum conductors and epoxy resin is studied by using a simplified coaxial structure specimen. The measurement system and finite element simulation are used to explore the generation of stress and strain during curing and shrinkage. The real-time measurement of strain at the interface shows that the residual strain in the entire process is primarily generated during the cooling stage. Consequently, the temperature and stress/strain distribution at the interface during the cooling stage are further studied, and combined with experiments and simulations. The consistency between the finite element simulation and the experimental measurement results verifies the validity of the simulation method used. The results show that the maximum of the first principal stress generated during the cooling stage of the production process is concentrated on the upper and lower edges of the interface which is critical to the impact of the production quality of the spacer.