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- Title
Vibration Responses of the Railcar Under Rail Irregularities: Case of Addis Ababa Light Rail Transit.
- Authors
Bizimungu, Gaspard; Nkundineza, Celestin
- Abstract
Purpose: Track irregularities contribute a large impact on the vibrations of a railcar. Therefore, this research is about assessing the impact of track irregularities on the rail vehicle vibration in the case of Addis Ababa Light Rail Transit Service. To assure the comfort of passengers in the railcar, it is important to monitor and identify rail irregularities that lead to rail-car uncomfortable vibrations. The objective of this research is to establish a method that uses rail irregularity measurement data and railcar design parameters to determine the railcar vibrations levels and frequency spectrum. Method: To achieve the objective, the analytical vibration equations of the half-railcar model with twelve degrees of freedom were derived and solved using MATLAB. The impact of periodic track irregularities on a bogie's primary rubber-made suspension materials was also analyzed in MATLAB. On the other hand, a 3D bogie lumped model with the railcar mass via secondary suspension and with Hertzian contact effects neglected in finite element model was analyzed to validate the analytical modal equations. The natural frequencies provided by 3D Finite Element Method (FEM) with full dimensions are compared with those obtained using lumped parameter model analytically. Results: The frequency of the car-body that corresponds to bounce motion provided by lumped parameter model was 14.89Hz, while the frequency obtained from modal analysis by FEM was 13.829Hz. Then, conformity of the frequencies in both models provided confidence in the correctness of the analytical model. The displacement of the railcar found was low and cannot cause fatigue to the vehicle components. Conclusion: As the significance of this research, rail irregularities that lead to a car-body vibration frequency spectrum that produces an uncomfortable ride can be carefully investigated to eliminate their effect, with reference to ISO 2631, which defines the methods for measuring human vibration levels and their effects on comfort. Their effect must be eliminated in the railway lines by either correcting the track or using appropriate railcar suspension parameters.
- Subjects
ADDIS Ababa (Ethiopia); BOGIES (Vehicles); STREET railroads; FINITE element method; FREQUENCIES of oscillating systems; DEGREES of freedom; MODAL analysis; HERTZIAN contacts
- Publication
Journal of Vibration Engineering & Technologies, 2023, Vol 11, Issue 7, p3535
- ISSN
2523-3920
- Publication type
Article
- DOI
10.1007/s42417-022-00766-8