Study on the Effect of Damping Asymmetry of the Vertical Suspension on the Railway Bogie Vibrations

Abstract

This paper has an original approach to the study of vibrations in the bogie of the railway vehicle by taking into account the asymmetry of the vertical damping of suspension. The study relies on the results derived from the numerical simulation applications, where the damping asymmetry of the bogie suspension is simulated through different degrees of reducing the damping of the suspension of one of the wheels compared to the reference value. Under such circumstances, the vibrations behaviour of the bogie, assessed in five reference chassis points—four points located against the suspension of each wheel and one point located against the bogie’s center of mass—will be the result of several combined effects. A first effect is produced by the suspension asymmetry that trigger interferences between the vertical vibrations of bounce and pitch and the horizontal roll vibrations of the bogie. Another effect is introduced by the reduction of the damping in the system. To these, the geometric filtering effect due to the bogie wheelbase is added, which has a selective nature depending on velocity. The analysis of the bogie vertical vibrations aims to assess the level of vibrations and identify the dominant vibration mode in the bogie reference points, as well as to determine the critical point of the vibration mode of the bogie, in correlation with velocity and the reduction degree of the suspension damping.