Dynamic detection mechanism model of acoustic emission for high-speed train axle box bearings with local defects

Abstract

Acoustic emission (AE), as a promising technology, is suitable for the fault diagnosis and state monitoring of high-speed train axle box bearings (HSTABs). However, the mechanism of the correlation between bearing states and dynamic AE signals remains unclear. Existing studies have failed to explain the relationship between contact deformation energy and dynamic root-mean-square (RMS) of the AE signals generated by HSTABs, while also neglecting the asperity-induced dynamic displacement and local defect-induced transient elastic waves. Moreover, there is no study on the attenuation behavior of AE waves in complete HSTAB. This paper presents an AE dynamic detection mechanism model of the HSTAB state, revealing the generation mechanism of AE waves by rough contact and local defect impact and their propagation characteristics. First, based on the load pattern of the HSTAB, a dynamic model was established considering asperity contact, local defect impact, and lubrication oil, and the dynamic contact force of the rollers was determined. Second, a mathematical model of the rough contact with RMS was established jointly with the contact force. Further, the attenuation features of the AE waves in the HSTAB and its housing were investigated, and an AE dynamic mechanism model was established. The model not only resolves the dynamic RMS characterization of the AE signals from moving bearings but also describes the relationship between the dynamic RMS and running speed, bearing state, and time scale. Finally, with different defective HSTABs as examples, the correctness of the model was verified by performing experiments on a full-size high-speed train test rig, providing a theoretical basis for the application of the AE technology in the diagnosis and quantitative analysis of bearing faults.