Influence of the interference of bounce and pitch vibrations upon the dynamic behaviour in the bogie of a railway vehicle

Abstract

The dynamic behaviour of the bogie of the railway vehicle is generally studied by capitalizing on the advantage of the symmetrical construction, which allows the vibrations in the vertical be considered decoupled from the ones in the horizontal plan. Likewise, the bounce and pitch vertical vibrations of the bogie are decoupled, due to the fact that elastic and damping elements with identical characteristics are normally used in the suspension corresponding to each axle of the bogie. The paper studies a particular situation, correlative with the failure of a damper in the primary suspension of a two-axle bogie. As a consequence of the damping reduction, an imbalance in the system occurs that will prompt dynamic interferences between the bounce and pitch vibrations of the bogie. The level of vibrations will rise, a fact focused on in the paper as based on the results from the numerical simulations, which represent the frequency response functions of the bogie calculated in the three reference points of the bogie, for different cases of reduction in the damping constant, compared with the reference value. The increase of the level of vibrations has an impact on the dynamic behaviour of the bogie, evaluated on the basis of the root mean square of the vertical acceleration.