A roll frequency design method for underframe equipment of a high-speed railway vehicle for elastic vibration reduction

Field measurements of the elastic vibration of a car body (CB) and its coupling with the underframe equipment vibration were carried out for a high-speed railway vehicle, it was found that there was a significant increase of CB elastic vibration when passing a particular location and the equipment absorbed little of the CB vertical elastic vibration. In order to reduce the CB elastic vibration, the suspension parameters of the underframe equipment in the roll direction were optimized. A simplified vehicle model including the roll motion of the CB and the underframe equipment was built for theoretical study, in which the modal displacement of the CB floor corresponding to the CB diamond mode was extracted from finite-element analysis. Based on the frequency response analysis, the frequency range in which the elastic vibration was magnified was obtained. By increasing the roll moment of inertia of the equipment and decreasing lateral distance between the suspension points, the roll frequency of the underframe equipment was decreased and the CB vibration was reduced. To verify the analysis, a three-dimensional multi-body dynamic railway vehicle system was established in SIMPACK. The optimized parameters were validated and shown to be effective for absorbing the CB diamond-mode elastic vibration.