Uniform Alternating Current Field Monitoring Sensor Array for Imaging and Quantitation of Cracks in Aluminum Alloy Structures

Aircraft structures are prone to fatigue cracks under various loads, which seriously threaten the safety performance of aircraft. Therefore, it is particularly important to carry out long-term structural health monitoring (SHM) for key nodes of aircraft structures. This article attempts to apply alternating current field measurement (ACFM) technique to the SHM field. In this article, based on the principle of ACFM, a uniform alternating current field monitoring (UACFM) technique is proposed. Through the simulation analysis, the change law of the corresponding monitoring characteristic signal is explored when the length, depth, and angle of the crack change, respectively. Based on monitoring images, a crack dimension quantitation method is proposed. In addition, by studying the optimal arrangement method of magnetic field sensor arrays, a UACFM sensor array for imaging and quantifying of cracks in aluminum alloy structures is produced, which can monitor the existence of the cracks. Several groups of different cracks on the specimen were tested. The results show that UACFM technology and the quantitation method proposed in this article can realize the imaging monitoring of the cracks, and preliminarily quantify the crack dimension (length, depth, angle), which verifies the reliability and effectiveness of this technology and provides a new method for SHM.