Failure Monitoring of Bolted Joints by Using Eddy Current Array Sensing Film

摘要

Bolted joints, the most important connecting type for in-service aircrafts, plays a significant role for aircraft structures because of their strong bearing capacity and high reliability. Nevertheless, due to large/complex load, stress concentration around the hole-edge and multi-bolt distribution, there exist three typical fatigue failure modes for the joint layer of bolted joint, mcluding shear-out failure, net-section failure and bearing failure. It is of great significance to estimate the failure mode for checking structural integrity and ensuring structural safety. In this paper, a novel flexural eddy current array sensing film produced with printed circuit technology is proposed to monitor the potential failure of joint layer. The eddy current array sensing film consists of an exciting coil and multiple sensing coils distributed in the axial and circumferential directions. The circumferential distribution of sensing coils is expected to identify the circumferential location of failure to estimate the failure mode, because different failure modes have different circumferential locations. Finite element simulation and experiment were both implemented to prove that the proposed eddy current sensing film is capable of differentiating the net-section failure, shear-out failure and bearing failure, and tracking its growth.