Tension Monitoring and Defect Detection by Magnetostrictive Longitudinal Guided Wave for Fine Wire Rope

Fine wire rope is a type of skeleton material that is used widely in elevator steel belts, conveyor belts, and synchronous belts. When the tension of a fine wire rope changes abnormally, its service life and the safe operation of the system it belongs to will be seriously affected. Therefore, it is particularly important to monitor the tension and detect the defects of fine wire rope. However, traditional nondestructive testing technology only detects the defects or monitors the tension of the tested structure. In this article, longitudinal guided wave sensors are used to measure the tension changes and defects of fine wire rope. When the tension of a fine wire rope changes, the natural frequencies of the fine wire rope change, so the change of natural frequencies of fine wire rope can be used to represent the change of tension. White noise is used to measure the natural frequencies of fine wire rope under varying tension using a low-power circuit to determine the influence of the change of fine wire rope tension on the natural frequencies. Meanwhile, the excitation frequency needed to produce the maximum amplitude of the guided wave is determined according to the natural frequencies detection results to improve the signal-to-noise ratio of the guided wave signal. Additionally, defect detection is realized by analyzing the wave velocity and time of flight of the guided wave signal.