Application of Electric Resistance Change Method to Damage Detection of CFRP Bolted Joints

Bolted joints are widely used for composite structures. As is well known, excessive bearing load gives rise to bearing failure at hole boundaries. Detecting bearing failure is important for assuring integrity of composite structures. Conventional nondestructive inspection methods are expensive, cumbersome, time-consuming, and not suitable for health monitoring, and a simple, low-cost inspection method for bearing failure must be developed. Authors have experimentally demonstrated detection bearing failure by an electrical resistance change method. In this study, detectablity of remote damage, which includes bearing failure, using an electric resistance change method is investigated analytically. The results show that fiber breaking and delamination induce permanent increase in the electric resistance of the bolted composite joints, and that the proposed method, which involves measuring electric resistance, is effective for detecting bearing failure.