Research On High-speed Passenger Dynamics Performance And Fatigue Strength Based On Flexible Frame

Higher speed and lighter weight are main trends in development of railway passenger vehicles. The former can effectively reduce passenger travel time and improve economic benefit, while the latter can decrease energy consumption and production cost. However, the higher running speed means greater excitation frequency, lightweighting reduces stiffhess of carrying structure, which may cause severe structure vibration worsening vehicle dynamic performance and fatigue life of components.The bogie is one of the most important components, which is responsible for the role in drawing, braking and carrying of the vehicles.Then the frame plays a main role in carrying of bogie, which transfers and weakens vibration between wheel and rail. The more speed increases, the more high frequency vibration between wheel and rail is aggravated. Vibration is transfered from the first suspension to frame, then to car body by the second suspension again. Because of damping effect of each absorber, vibration on the body is greatly reduced. However, the elastic vibration of frame structure may have adverse effects on weakening vibration, which affects the safety and reliability of the vehicle running.In the railway locomotives or vehicles, the hydraulic absorber plays an important role in smooth and safe operation for vehicle. When we study vehicle system dynamic response, the mounted stiffness of absorber which has been proved to play a certain effect is often an overlooked factor.Absorber with too large mounted stiffness will transfer high frequency vibration, which makes uncoordinated force or partial wear happen. However, if the mounted stiffness is too small or installation clearance is too large, effective stroke of absorber will be shortened, so it can not achieve desired damping effect.In this paper, high speed passenger system for dynamic response analysis based on flexible frames is done by the finite element and multi-body dynamics method in the simulation environment. The results show that vibration amplitude of the flexible frame is slightly larger than the rigid frame, because frame has generated structure elastic vibration especially in the high frequency range.Secondary, based on a quarter of vertical vibration model of vehicle systems with absorber mounted stiffness, research of railway vehicles systems dynamic responses with three different absorber characteristic parameters is done. Besides, it is focused on analyzing that mounted stiffness influences on the performance of the system dynamics in four kinds of absorber. The results show that mounted stiffness has a certain influence, especially in anti-hunting damper.Finally, analysis of fatigue life for frame is done based on UIC-ORE standard and random load spectrum method. The results show that the fatigue life for frame by random load spectrum method is lower than that by UIC-ORE standard.