Reduction of vertical abnormal vibration in carbodies of low-floor railway trains by using a dynamic vibration absorber

Abstract

A field test on the dynamic performance of a 100% low-floor railway train with five cars was conducted, and a vertical vibration at around 8 Hz was mainly studied for the background of the research. The vibration around 8 Hz, defined as the abnormal vertical vibration, was proved to be due to the pitching motion of the carbodies, which significantly affected the dynamic performance of the vehicle with a maximum increase of 0.309 in the vertical Sperling index. The dynamic vibration absorber theory was applied to reduce the abnormal vibration of carbodies to around 8 Hz by building a vertical mathematic model and a three-dimensional dynamical simulation model. The results of the theoretical analysis show that the stiffness of the articulated device between carbodies is the reason for the pitching motions at around 8 Hz, and the stiffness significantly affects the main frequency of the vertical vibration of carbodies. What’s more, the application of dynamic vibration absorber theory on low-floor railway trains can reduce the vertical abnormal vibration effectively. Yet, reasonable suspension parameters are needed; otherwise, the vibration of carbodies, including the mass ratio, the suspension frequency, the damping ratio, and the suspended location would be aggravated. Optimal suspension parameters of the dynamic vibration absorber system were used in the simulation model, and the result shows a good agreement with the numerical results; the attached dynamic vibration absorber system on carbodies significantly reduces the vibration of carbodies at around 8 Hz. However, it should be noted that the dynamic vibration absorber is only effective at high-speed stage (beyond 40 km/h) where the pitching motion of carbodies is obvious; this conclusion is consistent with the results of the field test.

A combined review of vibration control strategies for high-speed trains and railway infrastructures: Challenges and solutions

“…It is proved that the pitching motion of the car body can provide vertical abnormal vibration at around 8 Hz. For example, Wang et al 23 developed a DVA, installed it in different places of a train, and reduced abnormal vibration due to pitching of the car body. They also tested their DVA in a real HST experimentally.…”

Research on wheel wear of the light rail transit based on a modified semi-Hertzian contact model

“…The modern light rail transit (LRT), as one part of the ground transportation system, has effectively relieved the local traffic pressure and facilitated people’s travel demand. However, the complicated operational environment, including different weather conditions, bedding structures and extremely small radius curves, has made the wheel wear of the LRT more serious than the metro vehicle, including the wear depth and the wear width (Wang et al , 2017; Luo et al , 2017; Jeong et al , 2017). The worn wheel can reduce the vehicle running stability, worsen the ride comfort and even threaten the running safety in some extreme cases.…”

Experimental and numerical investigations on longitudinal vibration of suspended monorail trains induced by bogie pitching motion

“…heavy locomotives, 13 long freight cars, 14 train to train rescue 15 and even trams with asymmetric braking disks. 16 The positive aspect is to ultilise the longitudinal vibration in bogies as a dynamic vibration absorber to suppress the vertical bending mode of the carbody. The damping and frequency of the bogie longitudinal mode (5-12 Hz) is determined by the bogie mass, the traction rod stiffness as well as the yaw damping.…”