Vibration Analysis of Railway Passenger Car Systems by Considering Flexible Carbody Effect

The mathematical model of the vertical vibration for railway passenger car is established.The carbody is taken as an uniform Euler beam with free ends,and the semi-active damper in the secondary suspension system is taken into account.The definition of resonant speed for vehicle flexible mode vibrations and their calculation formulae are given.The resonant speed is the inherent feature of the vehicle system and is only related to natural frequency of the carbody and center distance of the bogie.The resonant speeds for the first and second vertical bending vibrations of the carbody and the corresponding wave length of the track are calculated.The harmonic and random vibration analyses of the vehicle system are carried out.The calculations show that the first bending natural frequency of the carbody should be far away from the natural frequency of vertical rigid mode of the bogie frame in order to reduce the resonance peak of the carbody.Due to flexible effect of the carbody,the acceleration and displacement at the ends of the carbody should be greater than the values in the middle of the carbody,and the ride index of the flexible carbody model be larger than the value of the rigid body model.Application of the semi-active damper can significantly reduce the acceleration,displacement and ride index of the carbody,but will increase the acceleration and displacement of the bogie frame.