Detection and Quantification of Fatigue Cracks in Rail Steel Using Acoustic Emission Technique

Abstract

Acoustic emission (AE) technique has a promising application for crack detection in rail tracks. However, it is still a challenging task to identify the size of fatigue cracks from AE signals. This paper proposes an index based on wavelet coefficients to accurately distinguish AE waves induced by crack propagation and crack closure, and a novel method of crack quantification based on crack closure induced AE waves. A higher count rate of crack closure induced AE waves indicates a larger crack size. The performance of the proposed method was validated by a three-point bending fatigue test on the rail steel specimen. In contrast with the traditional method, which is based on crack propagation induced AE waves and good at detecting crack growth rate, this method estimates the crack size without using the cumulative AE information, and is thus applicable to crack quantification of both new and existing structures. These two methods can be used to complement each other leading to a more efficient approach for crack detection, which has the potential for condition monitoring of rail tracks in the field. doi: 10.12783/SHM2015/314