Investigation on the Effect of Surface Scratch Damage on the Bending Resistance and Electrical Properties of Glass Fiber Epoxy Composites

Glass fiber epoxy composites (GFEP), widely utilized in high-voltage electrical equipment such as transformers and insulators, exhibit exceptional mechanical strength and dielectric performance. However, the effects of pre-damage mechanisms on their mechanical and electrical performance remain poorly understood. This study investigates the degradation the mechanical and electrical properties of GFEP under scratch-induced surface damage. Three-point bending tests were conducted on specimens with controlled surface scratches (0 mm, 0.1 mm, and 0.5 mm depths). Results showed that scratch depth significantly reduced ultimate bending stress, with a 22.2% decrease for 0.5 mm scratches compared to undamaged specimens. Electrical breakdown tests revealed that scratch damage lowered dielectric strength. It has been found that the insulation performance of GFRP decreased after fracture. This study highlights the crucial role of mechanical properties in the GFEP performance of electrical insulation applications, providing critical data for developing damage-tolerant insulation systems in HV applications.