Study on the Relationship between Bolt Anchoring Defects and Complexity of Nondestructive Testing Signal

• Published in: Russian journal of nondestructive testing 2021-11, Vol.57 (11), p.987-999
• Main Authors: Lei Zhang, Huang, Zhimin, Bai, Long, Ma, Zhanguo, Zhang, Lun
• Format: Article
• Language: English
• Subjects: Acoustic Methods; Characterization and Evaluation of Materials; Chemistry and Materials Science; Coal mines; Complexity; Defects; Empirical analysis; Materials Science; Nondestructive testing; Signal analysis; Stress waves; Structural Materials; Wave reflection
• ISSN: 1061-8309; 1608-3385
• DOI: 10.1134/S1061830921110127

—We combine the empirical mode decomposition (EMD) method with the multiscale entropy (MSE) method to quantify the number of internal defects in the bolt anchoring system so as to ensure the safety and reliability of the bolt anchoring structure. An experimental system for nondestructive testing (NDT) of anchoring quality is designed and manufactured by ourselves. On this system, the stress wave reflection method is used for NDT of the anchoring system in two kinds of conditions, with some or without defects. The EMD method is used to eliminate the high frequency components and trend terms in the detected signal, and then the MSE method is used to characterize the complexity of the reconstructed signal. The results show that the complexity of NDT signal of anchoring system with defects is higher than that of NDT signal of anchoring system without defects. And there is a clear corresponding relationship between the complexity of NDT signal and the number of defects. Moreover, an application example of this method in on-site NDT signal analysis of bolt anchoring system in coal mine is presented, which demonstrates the feasibility of this method in engineering application. It provides an effective way for quantitative evaluation of anchoring quality.