Vibration Responses of the Rail Car under Rail Irregularities:Case of Addis Ababa Light Rail Transit
No Thumbnail Available
Date
2019-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Distinct track irregularities contribute a large impact on the vibrations of a railcar from
different railway lines. However, the track irregularities and track stiffness will alter
over time due to the loading and environmental conditions. The measurements of rail
irregularities are required to assess and to determine their impact on railcar vibrations.
Ignoring these can significantly increase future maintenance costs on both vehicle and
track. Therefore, this research is about assessing the impact of track irregularities on the
rail vehicle vibration for the case of Addis Ababa Light Rail Transit(AALRT). The
equations of motion of the half railcar model with 12 dof have derived analytically and
solved using MATLAB. The irregularities used as excitation input to the MATLAB
model were measured along the track segment of AALRT lines at an interval of 150 m
each using a universal railway measuring ruler gauge for the track. For simplicity and
without loss of generality, the MATLAB model neglected the Hertzian contact effects.
On the other hand, the Finite Element Method (FEM) was used to validate the
analytical model equations by using modal analysis of the 3D railcar bogie. The natural
frequencies provided by FEM are compared with those obtained using lumped
parameter models. Then, the effect of suspension parameters on the railcar vibration
behaviour was investigated. The carbody responses of 14.89Hz and 13.89Hz from
MATLAB and ABAQUS respectively. The match of frequencies in both models
provided confidence in the correctness of the analytical model. These frequencies are in
the range of human sensitivity to vibrations, which is 0 to 20Hz as specified by ISO
2631. Thus, the vertical suspension components are very critical in vibrations of the
light rail vehicle and should be maintained regularly. It was also found that sleeper
stiffness variation has a small impact on vertical vibration responses on the railcar. The
research output may help to reduce the maintenance cost of the railcar by minimizing
the impact of track irregularities on rail vehicle vibration.
Description
Keywords
Train, metro, tram, rail car vibration, track, frequency, bogie, vibration