Study on Acoustic-Elastic Effect in Aramid Fiber Reinforced Epoxy Composites for High Voltage Insulation Pull Rod

Aramid reinforced epoxy resin composites are widely used in the molding of insulation parts of power equipment. Factors such as impregnation, curing process or external force during production or processing may cause residual stress in the aramid reinforced epoxy composite insulation. The tensile or compressive load under handover or operation conditions will be superimposed with the residual stress. When the stress exceeds the tolerance limit of the insulation material, micro cracks and other damages will be formed, which will lead to mechanical failure or insulation breakdown. In this paper, the ultrasonic longitudinal wave reflection method is used to test the standard specimen of aramid fiber reinforced epoxy resin. The relationship between the vertical compressive stress on the specimen and the ultrasonic longitudinal wave velocity in the specimen is studied, the acoustic elastic effect is verified, and the longitudinal wave acoustic elastic coefficient of the standard specimen whose ultrasonic propagation direction is perpendicular to the stress is calculated.