Identification of Multiple Defects from Rail Vibration Signals Based on Fast Kurtogram

Defects present in the wheel-rail system will seriously affect ride comfort and endanger driving safety. This study aims to identify slight changes in the vibrations caused by the geometric defects of the wheel-track system from the time-frequency characteristics of rail vibration signals, in order to analyze the wheel-track dynamic system for the purpose of defect testing. The fast kurtogram (FK) method is introduced to describe the vibration characteristics in different frequency bands caused by wheel-rail interaction, and capture abnormal vibrations from the characteristics of periodic pulse vibrations. To verify the effectiveness of the proposed method, in situ measured data were analyzed and the similarities and differences of vibration signals of the wheel-rail system when wheels passed over different track structural defects were compared. A coupled vehicle-track dynamic model of a train formation was established, and the abnormal vibration behavior of different wheelsets with polygonal wear when passing over a joint was simulated. It was found that this method can locate a faulty wheel with mixed defects. After processing the field data, the abnormal vibration signals were identified as coming from back-of-flange contact, demonstrating that the proposed method was capable of identifying abnormal wheel-rail dynamic responses. It was found that the FK method can be used to reveal the similarities and differences of vibration responses of different track defects, and can be used to evaluate the transient vibration of wheel-rail contact to locate faulty wheels with mixed defects.