Objective Carbody vibration in rail transit vehicles has become increasingly prominent. Traditional rubber elastic suspensions have a fixed vertical-to-lateral stiffness ratio, making it difficult to simultaneously optimize vertical and lateral vibration attenuation. To improve the vibration characteristics of heavy under-car equipment under high-speed operating conditions and enhance the overall vibration reduction performance of the equipment suspension system, it is necessary to carry out research on novel suspension vibration mitigation technology.

Method Based on negative stiffness theory, an under-car equipment vibration isolator with separated vertical and lateral stiffnesses is proposed and designed. By connecting disc springs with negative stiffness characteristics in parallel with rubber springs, the independent design of multi-directional stiffness is achieved. A three-dimensional rigid-flexible coupled nonlinear vehicle dynamic model incorporating elastic carbody modes is established, and the accuracy of the model is validated through real-vehicle line tests. Based on this model, the effects of four suspension schemes - rigid suspension, theoretical vibration isolation suspension, dynamic vibration absorber suspension, and negative stiffness vibration reduction suspension - on carbody vibration and ride index are systematically compared and analyzed at operating speeds of 250~400 km/h.

Result & Conclusion The scheme adopting the negative stiffness vibration reduction design can effectively reduce the acceleration amplitude in the elastic vibration frequency band of the carbody. Especially at speeds below 300 km/h, the carbody vertical vibration acceleration and vehicle ride comfort index under this scheme are the lowest among the four schemes.