|Title:||Damage detection and localization for train axles based on quasi-surface waves|
|Advisors:||Cheng, Li (ME)|
|Subject:||Railroad trains -- Axles|
Hong Kong Polytechnic University -- Dissertations
|Department:||Department of Mechanical Engineering|
|Pages:||xiv, 80 pages : color illustrations|
|Abstract:||Axles play a vital role in trains as the main load bearing structure of the bogie system. Considering the increasing demand for high cruise speed, any defect or damage in the axles may cause catastrophic consequences. Therefore, a damage inspection scheme for train axles is highly required to ensure the operational safety of trains. In this dissertation, quasi-surface waves are proposed for the detection of high-speed train axles due to their appealing features like large region monitoring capability, high sensitivity to small defects, etc. In order to understand the propagation characteristics of the quasi-surface waves, finite element (FE) method is applied. FE results show that quasi-surface waves exhibit outstanding characteristics in the propagation over the cylindrical surface of a solid cylinder, like no dispersion and constant group velocity. Meanwhile, two FE models are established, proving that the cylindrical curvature has negligible influence on the propagation speed of the surface waves. A damage localization algorithm and the associated sensor network arrangement are proposed. A FE model is established with four transducers serving as a sensor network for the detection of a 5mm semicircle crack in the cylinder. Following the configuration of the FE model, experiments are conducted using a baseline method based on the results from intact and cracked cases. A fairly good agreement is found among the FE simulations and experiments, thus confirming the feasibility of the proposed detection methodology. This work, as a whole, establishes the fact that quasi-surface waves can be effectively generated in a cylinder structure and captured using PZT sensors. In addition, damage localization experiments, carried out on the outer surface of the cylinder using the proposed localization algorithm, demonstrate that damage can be accurately localized by the proposed method. The study reveals various physical phenomena thus providing useful guidelines for quasi-surface wave-based SHM technology in terms of both system design and SHM diagnosis.|
|Rights:||All rights reserved|
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