Contribució a la detecció de defectes singulars en els perfils de les rodes de ferrocarril mitjançant l’anàlisi de les vibracions generades en el contacte roda-carril
One of the main problems presented due to the defects in the profiles of the railway wheels is the generation of vibrations and noise, and their propagation towards the environment. Defects in wheels, such as surface pitting and wheel flats (very common in trains of metro lines, generated by constan...
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| Format: | doctoral thesis |
| Status: | Published version |
| Publication Date: | 2019 |
| Country: | España |
| Institution: | CBUC, CESCA |
| Repository: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/667267 |
| Online Access: | http://hdl.handle.net/10803/667267 https://dx.doi.org/10.5821/dissertation-2117-166472 |
| Access Level: | Open access |
| Keyword: | Àrees temàtiques de la UPC::Enginyeria mecànica 531/534 629 |
| Summary: | One of the main problems presented due to the defects in the profiles of the railway wheels is the generation of vibrations and noise, and their propagation towards the environment. Defects in wheels, such as surface pitting and wheel flats (very common in trains of metro lines, generated by constant braking due to the proximity of the stations), produce vibrations that can reach undesired levels. To avoid this, a monitoring of the state of the wheels must be carried out. The implementation of a system for the acquisition of vibratory signals, generated by the wheel-rail contact, installed on the track, allows permanent control of the status of the wheels, having flexibility when performing maintenance and lowering costs. If no defect is detected in any of the wheels of the train, it should not be removed from the railway network. The main objective of this thesis is to develop a methodology to detect the main types of singular defects in the profiles of the wheels by analyzing the rail vibrations generated by the wheel-rail contact during the passage of the train. The analysis of the recorded signals will be performed in the time domain because the singular defects of the wheel profiles generate transient random vibrations. The passage of the train is already a transitory. In fact, the temporary reference cannot be lost. First, theoretical wheel flats are characterized, and a study of the irregularities of some wheels measured experimentally is done. Synthesized irregularity profiles are also analyzed. The types of metropolitan road are modeled dynamically. A wheel-rail contact model is deduced using Hertz's nonlinear contact theory; it allows to obtain the temporary evolution of the wheel-rail contact force (double convolution algorithm) using different wheel flats and irregularity profiles as input perturbation. Then the vertical vibration speed of the rail is obtained when a wheel passes over a fixed location of the track (variable kernel convolution algorithm), which is associated with the point where the vertical vibration recording system is installed in one of the rails of the track. Several wheel-turns upstream and downstream are simulated by moving the wheel along the rail at a speed of 45 km/h (usual passage speed over the experimental point of measurement). An attenuation model of the vertical vibration speed of the rail is also made as a function of the distance from the point of wheel-rail contact and the point of measurement. With the simulations of wheel passages with synthesized profiles, a time evolution of the RMS value of the vertical vibration speed of the rail is obtained; it will be the base function that will be used to develop the method of detection of the defects of the wheel profile. The detection method consists of adjusting a base function for each wheel passing above the measuring point to the time evolution of the RMS value of the experimental registry of the vibration speed to the passage of a train. An evolution of the theoretical RMS value is obtained, which will be the reference function to be compared with the current evolution of the RMS value and thus be able to detect which bogie may contain any wheel or wheels with some singular defects in its profile. Vibration records are obtained from the performance of experimental measurements in Line 3 of FMB, and others from previous theses. Having this detection method will allow the development of predictive maintenance algorithms and detect the severity of defects caused by continuous rolling. It will allow taking the appropriate actions in a specific way for each train when wheels with these defects are detected; a history of vibration levels and detected defects will be made to correlate these levels and the defects according to type and magnitude. |
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