A Novel Pentagonal EC Sensing Array Film for Quantifying Hole-Edge Crack of Bolted Joints

Hole-edge crack in bolted joints is one of the most critical damages that seriously affect aircraft structural safety. In this article, a novel pentagonal eddy current (EC) sensing array film is proposed to quantify the hole-edge crack parameters. The proposed new sensing film may identify the hole-edge crack angle, depth, and length with fewer layers and eliminate the blind area problem of crack monitoring for the existing sensors at some angles. Finite-element simulation is employed to study the EC distribution around the bolt hole and the interaction between the EC and the crack, which can be used to determine the configuration of the EC array. Both the simulation and the experimental test are conducted to verify the feasibility and effectiveness of the proposed sensing film for quantifying the hole-edge crack angle, depth, and length.