| As the speed of rail vehicles increases,new requirements are placed on the performance and reliability of the running department of the vehicles,and a large number of new structures have also been adopted on the bogies.Among them,the trailing arm type axle box positioning method is widely used in the bogies of high-speed EMUs and urban rail vehicles due to its characteristics of compact structure,reliable performance and no wearing parts.As a mechanical device that restricts the relative movement between the wheelset and the frame,the axle box positioning device directly affects the dynamic performance of the bogie.It is an important task to design this device in the design of bogies.The trailing arm type axle box positioning is a unique structure of the wheelset positioning method,there is only rotational degree of freedom between the wheelset and the axle box,the wheelset and the left and right trailing arm axle boxes are as a whole,and are connected to the frame through the rubber joints to form a special quadrilateral structure with a certain degree of freedom restricted.The kinematic relationships of this device is complicated,and there is a high requirement for the movement compensation ability of the rubber joint.It is necessary to systematically analyze the kinematic relationships,positioning stiffness characteristics and the reliability of key components of this type of axle box positioning device.This thesis completes the following tasks for the most common primary spring top-mounted trailing arm type axle box positioning device:1.Analytical methods are used to derive the calculation formulas for the longitudinal,lateral and vertical positioning composite stiffness of the axle box.The mechanics model is established in SIMPACK,and the simulation verifies the correctness of these formulas.On this basis,the main factors that affect the positioning stiffness of the axle box are analyzed,and the composition mechanism and changing law of the positioning stiffness of the axle box are clarified,which has guiding significance for the allocation and determination of the primary suspension parameters.2.Analyzing the horizontal and vertical motion relationships of the trailing arm type axle box positioning device,and give the motion compensation requirements of the rubber joint.The analysis of the lateral motion relationships takes the lateral force of the wheel shaft as the input,and the calculation method of the lateral displacement of the wheelset and the compensation of the joint is derived.The analysis of the vertical motion relationships mainly considers the unilateral vertical motion of the wheelset,and giving the calculation method of the rubber joint compensation amount due to the space rotation of trailing arm caused by the degree constraint between the axle box and the axle.3.When the wheel set bounces on one side,the space rotation of the trailing arm is caused by the constraint of the degree of freedom between the axle box and the axle,and the vertical parasitic stiffness will be formed by the constraint of the rubber joint.The parasitic stiffness was studied and analyzed,calculation formula was deduced,and the accuracy of the formula was verified by SIMPACK.Taking the trailing arm axle box positioning device of a certain type of subway bogie as the object,the parasitic stiffness of the positioning device is compared with the vertical stiffness of the primary spring.The research shows that the vertical additional stiffness is a very small amount and does not affect the wheelset’s unilateral motion.The force change of the axle box positioning device is analyzed,and a calculation method for wheel load reduction when the wheelset passes through the twist of track is given.4.The rubber joint is a key component of the positioning device,and its reliability is the guarantee of driving safety.Taking a certain type of subway bogie axle box positioning device’s rubber joint as an object,the load time history of the joint is obtained by SIMPACK simulation.Using ABAQUS and FE-SAFE,the influence of multi-axis loads formed by different combinations of longitudinal,lateral,torsional and deflection loads on the fatigue life of the joint is analyzed.Results show that in addition to the longitudinal and lateral loads,the deflection load on the joint also has a certain influence on its fatigue life.It is pointed out that the influence of the deflection load on the fatigue life of the rubber joint should be considered in the fatigue test. |
