Heuristic models for wear prediction and dynamic-based condition monitoring techniques in pantograph-catenary interaction
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Railway catenaries are key components of electric railways, representing for the trains both their power source and their performance limiter. Although the amount of electrified railways is noticeably lower than the non-electrified railways, they are the preferred choice for high-speed railways and heavy freight lines. Thus, electric railways constitute an important topic of discussion and, ultimately, of research. The quality of the contact is of primary importance, as well as the study and the monitoring of the system during a life-cycle of regular traffic operations. This thesis focuses on the study of the system condition monitoring and the wear modelling and prediction in the pantograph-catenary interaction, tackling the issue from different perspectives. A first work on the monitoring of the contact wire tensioning forces was carried out as a continuation of previous studies on the catenary dynamics. Having already a monitoring system available and in use for evaluating the modal parameters of the catenary, the idea of using the same acceleration caused by the passing train to detect changes in the contact wire tensioning forces was successfully implemented. In this way, a simple, yet effective, method that uses easily obtainable data was built, allowing the monitoring of an important parameter that directly affects the performances of an electric railway. From the other side of the contact a study was carried out on the dynamics of the pantograph, testing the response of its components to a frequency band broader than usual. This study allowed to detect which component might be more prone to be excited by certain frequency, and also gave an insight into what can be an effective approach for this type of study on different pantograph models. In parallel with these two studies, more focused on the dynamic of structures and mechanical systems, a work more centred on the wear modelling in the pantograph-catenary interaction was carried out in collaboration with the Department of Mechanical Engineering at Politecnico di Milano. A test rig specifically designed for the study of wear in contact strip and contact wire under different operating conditions was used, and two important outcomes were obtained, resulting in an equal number of publications. The first result was the building of two models, one for the contact strip and one for the contact wire, for the representation of wear depending on operating parameters such as uplift force and current intensity. The second result extended the validity of the model for the contact strip to the new variable of the contact point lateral speed. This parameter, which has not been receiving much attention within the research, proved to be important when it comes to the wear in pantographs that run on lines that operate mixed traffic. While the first paper provides a model for the wear and a suggestion on the best operating conditions, although very specific for the Norwegian case, but with a process that can be replicated for different railways, the second provides a suggestion over the choice of design parameters.