الفهرس 
INTRODUCTION AND LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
This thesis aims to show the feasibility for improving the ride quality of railway vehicles
with semi-active secondary suspension systems using magneto-rheological (MR)
dampers. A nine degree-of-freedom railway vehicle model, which includes a car body,
two trucks and four wheel sets, is proposed to cope with vertical, pitch and roll motions of
the car body and trucks. The governing equations of the railway vehicle suspension
systems integrated with MR dampers are developed by using Newton’s second law of
motion. A Bouc-Wen model for hystresis of MR damper and a model for railway track
irregularities due to its elasticity are also considered. A proposed sliding mode control
with desire value of train car vertical acceleration is adopted as the system controller. In
order to make the MR dampers track the optimal damping forces, a damper controller to
command the voltage to the current drivers for the MR dampers is used. The acceleration
responses of the car body of the train vehicle with semi-active secondary suspension
system integrated with MR dampers are evaluated due to railway roughness, track
elasticity, and pulse excitation. The performance of sliding mode control is compared to
Linear Quadratic Gaussian (LQG) control in which the state variables are estimated from
the measurable accelerations. The performance is also compared to the conventional
passive suspension system using viscous dampers without MR dampers, and the
secondary suspension system integrated with MR dampers in passive on and passive off
modes. The simulation results show that the vibration control of the train suspension
system with semi-active controlled MR dampers is feasible and effective, and the sliding
mode control method is more effective than both the passive control and the LQG control
in suppressing the vibration of the car body and reducing the transmitted forces. The
simulation results also show that the effect of the railway track elasticity is very small
and can be neglected with respect to common amplitude of the periodical track roughness.