EFFECTS OF NUMBER OF PLIES ON LIGHTNING STRIKE PROTECTION OF ELECTRICALLY CONDUCTIVE LAYER-WISE HYBRID LAMINATES

Abstract

With the development of composite technologies, aircraft become lighter and more fuel efficiency. The composite aircraft, however, become susceptible to lightning strike. Developing lightning strike protection (LSP) system need to couple with composite technologies. The authors present a concept of LSP using layer-wise hybrid laminates (CF/Hybrid) in this study. The aim of the study is to validate the effectiveness of layer-wise hybrid laminates structure for lightning strike application by using conventional epoxy-resin CFRP for main structure and electrically conductive layer as a cover layer. The composite laminates include two different types of resin in each layer: conductive polyaniline-based matrix (CF/PANI) and conventional epoxy resin (CF/epoxy). CF/PANI layers varied from 1, 2, and 4 layers with corresponding 7, 6, and 4 layers of CF/epoxy to find out the least effective number of CF/PANI that can prevent lightning strike damage. The specimens were characterized for their mechanical properties and underwent simulated lightning strike test to realize their effectiveness. The result of simulated lightning strike has shown that a layer of conductive CF/PANI can help to avoid catastrophic damage on CF/epoxy. With a greater number of CF/PANI, the less detectable damage in CF/PANI layer became. In the case of CF/Hybrid with 4 layers of CF/PANI shows 70% residual bending strength after the lightning strike. With the aid of nondestructive inspection tools, i.e., thermography and ultrasonic test, the mechanism of damage on the composite panels were observed and analyzed. From this study, CF/Hybrid with 4 layers shows the optimal properties for lightning strike protection.