Electrical insulation and dielectric properties of aramid fiber reinforced epoxy composites under mechanical stress

In this work, an in-situ testing platform that could simultaneously apply high voltage (HV) and mechanical stress has been established. The dielectric properties evolution of aramid fiber reinforced composite (AFRC) under different tensile stresses is investigated systematically. The results show that there is a significant influence on the electrical insulation performance of AFRC, when the applied tensile stress reaches 45 % of the ultimate tensile stress (UTS). Elevated tensile stress will induce interface strain concentration inside composites under this condition, which is prone to cause local damage and defects, consequently enhancing charge accumulation under HV. As the tensile stress continues to increase, it is observed that the absorbed charge around defects increases by 49.4 % under 60 % UTS, accompanied by a discernible decline in the partial discharge inception voltage (PDIV) by 46.9 %. With the increase of absorbed charge, the localized intense electric field is formed, thereby fostering partial discharge and breakdown failure. Therefore, it is important to pay more attention to the evolution of dielectric properties of AFRC under mechanical stress in the design and assessment of aramid-based insulation rods. © 2014 xxxxxxxx. Hosting by Elsevier B.V. All rights reserved. [Display omitted]