Research on the Residual Stress Detection of Epoxy Resin Based on Acoustoelastic Effect

Epoxy resin is one of the important insulating materials for HV equipment. The factors such as curing temperature, time or external mechanical forces during manufacture or processing are easy to produce residual stress within the epoxy resin. When the epoxy-based insulator is put into operation, the load it bears and the residual stress are superimposed, resulting in micro defects and other damages. Partial discharge or even breakdown easily occurs around the defects under strong electric field. As a nondestructive testing method, ultrasonic method has the advantages of convenient operation, high detection efficiency and no pollution. It is a new way to detect residual stress. At present, there are few stress detection methods for non-metallic materials, especially the detection methods of residual stress under the influence of process conditions. In this paper, in order to detect the residual stress of epoxy-based insulating materials, the artificial epoxy resin samples are detected by acoustoelastic effect and ultrasonic longitudinal wave reflection method, and the effects of curing temperature and time on the residual stress are studied. The relevant results are of great significance to guide the production of epoxy-based insulating materials and improve the reliability of HV equipment.