Localization of steel strand damage based on Empirical Mode Decomposition algorithm

In order to accomplish rapid detection of the damage in mooring steel strand of the offshore platform this paper proposes to use the ultrasonic guided wave method for the online damage detection. Considering the non-stationary characteristics of the ultrasonic signal, this paper proposes an Empirical Mode Decomposition} (EMD)-based algorithm to detect and localize the position of steel strand damage. To be specific, the detect signal is firstly decomposed by EMD into multiple Intrinsic Mode Functions (IMFs). Then, in order to find the weak damage signal which is usually buried in noise, a weighted synthesis procedure is adopted, i.e., assigning more weights to the dominant components of IMFs. By doing so, the reconstruction signal is denoised and the damage signal can be much more easily captured. Simulation results show that the proposed method can effectively detect the ultrasonic guided wave signal and realize the accurate localization of the weak damage to the steel strand by comparing with the traditional method of directly selecting several natural IMFs.