Research On The Measuring Methods Of Freight Car Bogie Dynamic Parameters

With the acceleration of passenger trains speed along the key railways in China, it becomes urgent to increase freight trains speed, in which bogies play a key role. But the majorities of freight car bogies in China are three-piece, which can't meet the demands of acceleration and must be reconstructed. At the same time, new type of freight car bogies must be developed.Experiments play an important role in developing new type of freight car bogies, which include characteristic testing of bogie components, testing of bogie dynamic parameters, experiments on roller rig and on experimental line. In the past, due to lacking of special rig, bogie dynamic parameters were tested on other experimental equipments generally, which has some limitations. In this paper, according to the characteristics of freight bogie dynamic parameters' testing, a Servo-controlled hydraulic rig is designed. On the base of analyzing the function requirements, the scheme of the rig is proposed, which includes the principle design, the layout design, and the elemental structure design.And by means of the finite element method, the stiffness, strength and model analysis is carried out. According the elemental structure established in the conceptual design and the imposed load during experiment, the stiffness and strength of the rig's main component, including the plate-1, the plate-2 and the portal frame, are calculated. Because the portal frame is also used in the rig for bogie fatigue strength testing, in which the imposed load is harmonic, the modal analysis is necessary. The fundamental vibration mode shapes and corresponding frequencies are calculated to validating that the natural frequencies of the structure have enough difference comparing to the load frequency, so sympathetic vibration can be avoided.And then according to the characteristics of the designed rig, the measuring methods of freight car bogie dynamic parameters are studied. The measuring schemes of dynamic parameters are proposed, which include bend stiffness, shear stiffness, wrap stiffness of three-piece bogie, damper friction coefficient,centerplate and bolster friction moment, primary and secondary suspensionstiffness.