Electrical properties study of fibre reinforced polymeric materials used in aircraft structures

Aircraft are exposed to lightning strikes. Lightning strike protection (LSP) devices involve additional weight of the aircraft. Therefore, multifunctional materials that allows the conductivity of electrical current and, simultaneously, holds the mechanical properties required to withstand the typical conditions for an aerospace material are widely researched. A typical resin used in aviation is an insulator, so main research is done to reduce its resistance. On the other hand, the type of reinforcement can have a large influence on the electrical conductivity in the plane of reinforcement. The aim of the article is to evaluate the effect of the type and the basis weight of reinforcement on the electrical conductivity. For this purpose, with the use of a hydraulic press, different four-layer composites based on epoxy resin were produced. Each differing is in combination of carbon, glass layers and their basis weight (from 48 kg/m2 to 245 kg/m2 ). The measuring proceedings were carried by an RMS multi meter and, more accurate, by an LCR meter with 4 selectable test frequencies. The measurements were made both along the strand fibres and at a 45-degree angle. The results made it possible to determine which reinforcement of aircraft composites should be selected at the aircraft design level to provide increased electrical conductivity along the reinforcement fibres and thus influence one of the factors affecting the protection of the aircraft against the effects of lightning