The Influence of Wheel Flat for Low-Speed train Performance due to Contact Load: A Case Study of Ethio-Djibouti Railway (EDR
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Date
2023-04
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Addis Ababa University
Abstract
Wheel flats are the most common defect that occurs during train operation. When a train wheel is locked during braking, wheel sliding happens, and as a result, wheel flat rises this wheel flat causes severe impact load on both the vehicle and track components, which leads to excessively damaged railway vehicles and tracks. In this scenario, the Low-speed performance of a train generates higher friction on the wheel/rail contact, which causes wear and defects like wheel flat.
The rigid multi-body system dynamics simulation considered wheel flat defect and track irregularity were established based on SIMPACK software. The present research work is validated based on measurements and relevant research literature. The current work considered the changes in vehicles running speeds from 40km/hr to 100km/hr and wheel flat lengths from 25 mm to 85 mm and studied the dynamic response (vertical force, lateral force & acceleration of the car body), comfort (vertical/lateral), Ride index (vertical/lateral), the influence of speeds.
The results of the analysis showed that the impact load typically rises with running low-speeds and wheel flat lengths, while other parameters, such as vertical acceleration along with its amplitude and power spectrum density rise and reach a maximum value at a specific speed of 70 km/hr, after which it begins to significantly decline.
Finally, the results of impact force for the railway vehicle running at different low speeds and with different wheel flat lengths were analyzed with the warning and alarm limts of impact force that can damage the vehicle and tarck components to classify the running condition as safe, moderate and severe operating condition based on the maximum impact force due to the defects.
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Keywords
Wheel Flat, Rigid Wheelset, Multibody Dynamics, Track Irregularities