PhD Research by Maider Oregui
02/01/2010 - 07/01/2015
characteristic frequencies, fastening modelling, hammer tests, variability in the track, vertical track dynamics,
Basque Government of Spain, TU Delft
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Extending the service life of railway tracks is a challenge for infrastructure managers as tracks have to withstand harder service conditions for longer time and at lower costs. Regarding the service conditions, the railway transport moves towards faster and heavier trains which accelerate the degradation of the tracks. To improve safety, high cost maintenance measures are taken, for example grinding of the rail top or rail replacement. A better understanding of the interactions and physics occurring in the complex vehicle-wheel-rail/track system helps slow-down the deterioration, and consequently, lowers the life-cycle costs.
To gain insight into the dynamics of tracks, hammer test measurements and numerical models are often combined. In my PhD project, I have combined sets of field hammer test measurements, which were examined at healthy and damaged conditions, and state-of-the-art models of the sleeper-fastening-rail interaction.
From the examination of measurements, contributions are made in these three aspects. First, a method that considers the intrinsic variability of tracks is proposed to define the baseline state of tracks. Second, possible characteristic frequencies of damaged insulated rail joints are identified. Third, a statistical method to identify the characteristic frequencies of damaged railway tracks is presented. As a feasibility study, the rail surface defect squats are investigated in two ballasted tracks. The identified characteristic frequencies are expected to be useful in the development of early-detection vehicle-borne inspection systems.
The numerical analysis of the 3D FE models and the comparison to field measurements results in three contributions. First, insight is gained into the main characteristics that define the dynamic behavior of tracks with monoblock sleepers. Second, a 3D FE model is developed for tracks with monoblock sleepers to derive track parameters. Third, the influence of the fastening representation in the vertical dynamic behavior of tracks is extensively investigated.