Contribución a la metodología de caracterización dinámica de materiales resilientes para aplicaciones ferroviarias

• Autores: Washington Salvatore Reina Guzmán
• Directores de la Tesis: R. Arcos (dir. tes.), Arnau Clot Razquin (codir. tes.)
• Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2021
• Idioma: español
• Materias:
  • Física
    • Acústica
      • Vibraciones
  • Ciencias tecnológicas
    • Tecnología de materiales
      • Ensayo de materiales
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• Resumen

  • This thesis is focused on the enhancement and development of advanced methodologies for the dynamic characterisation of resilient elements used in railway applications. On the one hand, this thesis proposes several improvements to the application of the indirect method described in ISO 10846 standard for determining the dynamic stiffness of resilient elements using a swept-sine excitation. Within this framework, this work proposes a method that allows to design the swept-sine excitation parameters in order to ensure a predefined maximum error of those estimated frequency response functions that are needed to determine the dynamic stiffness. This method is based on a procedure that uses a numerical simulation of the test-rig and the resilient element of study which allows to predict the error made as a function of the excitation parameters and of the existing background noise, allowing to optimise the test in terms of required time and results quality. The method is then validated experimentally for two case studies: a sample of an elastomeric material and a coil spring. This work has also studied the influence that the experimental setup, the static preload and the dynamic loading have on the estimation of the frequency response functions. On the other hand, this thesis considers the adaptation of an existing in situ methodology to laboratory testing. The methodology allows to determine the dynamic stiffness of an elastic element in a broad frequency range with a single test. This alternative methodology has been validated using the two case studies previously mentioned. By including the improvements made to the indirect method to this methodology, it is possible to obtain a simple and robust method that can take into account the uncertainty related to several effects such as the excitation, the background noise and the experimental setup. Finally, the dynamic stiffness results obtained for both case studies have been compared to the results obtained using standardised methods such as the direct and indirect methods. From these comparisons it can be concluded that the proposed alternative method is the best choice to determine the frequency dependence of the dynamic stiffness, specially at high frequencies, as it allows to perform a broad-band characterisation in a single test and it overcomes the problems induced by the inertia forces found when the direct method is applied at high frequencies.