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 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 simula