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Development of an Experimental Setup to Analyze Carbon/Epoxy Composite Subjected to Current Impulses



The use of composite materials is significantly growing in the aircraft industry because of their lightweight, high specific mechanical properties, such as strength and stiffness. These benefits are a potential improvement in aircraft design to save weight and reduce fuel consumption. A carbon fiber reinforced polymer (CFRP) composite is one of the types used for aircraft structural applications. Carbon fibers are mechanically stronger and lighter than aluminum. In a CFRP composite, carbon fiber acts as reinforcement and provides mechanical strength, and epoxy resin is the supporting matrix. Therefore, carbon fibers greatly improve composite’s overall material properties. They can be fabricated in a desired stacking sequence, with various fiber orientations. From an electrical point of view, a composite can be designed so that it will conduct current asymmetrically in one direction as compared to another. A fiber orientation in a CFRP composite results in strong anisotropic material properties. This indicates that the composite exhibits different conductivity in each direction, along the fibers or transverse to the fibers. In this paper, variation in electrical properties of CFRP caused by relatively low magnitude current impulses discharged through CFRP coupons are reported, and internal changes of the composite, due to current impulses, are studied. Based on electrical resistance measurements caused by these currents, property changes in CFRP composite coupons of two different carbon ply orientations are compared. Furthermore, it will be investigated if the changes caused by current impulses are mainly focused in the region of the current injection at the edges of composite coupons, or are they distributed uniformly through the bulk of the composite.

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