Suspension Damping Influence on Ride Comfort of Passenger Rail Vehicle
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Date
2015-05
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Addis Ababa University
Abstract
This paper analyzes the secondary suspension damping influence of a passenger rail vehicle
upon the ride comfort, evaluated via the sterling ride comfort index. The selection of damping
ratio is a sensitive issue when a too small damping may compromise the vehicle dynamic
performance, and a too high damping leads to an increase in the system dynamic rigidity and,
therefore, to an intensification of the vibration behavior.
The complete model of a vehicle with two suspension levels and a flexible car body has been
taken into consideration. Upon applying the modal analysis, a new form has been provided for
the movement equations that describe the symmetrical and anti-symmetrical movements of the
vehicle and their modes of excitation. This work is focusing on optimization of suspension
damping coefficient to improve the ride comfort of passenger rail vehicles. In doing rail vehicle
body movement equations carried out and performed by MAT-LAB.
An increase in the damping of the secondary suspension may trigger a decrease of the comfort,
in dependence with the position along the car body and the velocity. At car body Centre, it will
lead to lowering the resonance amplitude for low velocities, whereas the vibration intensifies at
higher velocities, thus increasing the Wz index. Above bogie, the increase of ζc has a favorable
impact upon comfort, irrespective of speed. At 50 km/h and the same damping ratio ζc = 0.3,
there is a lower comfort index Wz by 4%, at car body center and above bogie by about 2 %. The
secondary suspension damping greatly influences the ride comfort. This is the reason why the
issue of selecting this damping requires a solution of compromise. The primary suspension
damping enhances the comfort, but its increase is limited by the wheel/rail dynamic overloads.
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Keywords
Passenger rail vehicle, Ride comfort, suspensio damping coefficient, power spectral density of acceleration, sperling index