An assessment on brittle fracture of composite insulators´ rods and factors improving their properties

Different mechanisms of the brittle fracture of a composite insulator´s rod, manufactured by a pultrusion process with a given percentage of fiberglass (70-75% by weight), have been investigated in this research. The epoxy-fiberglass composites made in this way show high tensile strengths under normal conditions, but they are sensitive to environmental factors while under electrical and mechanical stresses, and thus corrosive environments, temperature and stress can affect their properties with time. This is due to the fact that the composite consists of a large number of fiber-resin interfaces. The occurrence of failure in any of these interfaces will lead to the diffusion of moisture which in turn will be condensed to water. It can be concluded from the results that the following factors greatly influence the brittle fracture of the rod: type and chemical composition of resin and the fiberglass used, and fiber weight percentage in the rod. Thus by changing the chemical composition of fibers and also by increasing the fiber-resin compatibility, the long-term tensile properties of the rod can be significantly improved