New Entropy-based Vibro-acoustic Modulation Method for Metal Fatigue Crack Detection: An Exploratory Study

Abstract Metal fatigue is a typical industrial failure, and investigations on monitoring of fatigue cracks are required. Therefore, in this study, we developed an exploratory study by proposing a new vibro-acoustic modulation (VAM) method to monitor fatigue crack. To simulate different fatigue crack width, a mechanical auxiliary device was designed, and a surface profiler was employed to measure crack width. Compared to traditional VAM, we replaced the shaker through the PZT transducer, and both low frequency (LF) and high frequency (HF) excitations were based on linear swept sine waves. Then, a new entropy-based damage index (DI) using the multiscale permutation entropy (MPE) was developed to characterize the crack width. According to experimental results, there was a one-to-one relationship between the DI and the crack width, particularly, without saturation. Therefore, we demonstrated the capacity of the new VAM method to monitor crack propagation process, which can guide future investigations.