Research On The Mechanical Properties Of Air Springs And Their Influence On Vehicle Systems

With the rapid development of China's high-speed railway technology,safety,high speed,punctuality and comfort have become our goal.The problem of vehicle vibration has also become the focus of scholars' research.When the vehicle is running at high speed,it will be excited by the track irregularity,causing vertical vibration and lateral vibration of the vehicle and components.The air spring is an important component in the entire damping system of the vehicle.The main advantages are the height adjustable,the ability to provide large damping,large displacement,and non-linear stiffness.Studying the influence of air spring parameters on vehicle dynamics can provide reference for air spring improvement and improve vehicle running quality,which has great practical significance.Firstly,the finite element model of air spring is established by finite element software ABAQUS.The mechanical properties of the air spring of the second suspension of the vehicle are studied.The displacement-load response curve and internal stress cloud diagram of the air spring are obtained.The static stiffness of the air spring is calculated according to the obtained response curve data.Dynamic stiffness,study the influence of air spring parameters on its mechanical properties.Secondly,the dynamic model of the vehicle body,frame,wheelset,series of vibration suspension system,second-line vibration suspension system,track and other components is established in the multi-body dynamics software UM,and the parameters such as air spring stiffness and damping are studied.Vehicle dynamics impact.Finally,this paper comprehensively compares and analyzes the effects of different stiffness and different orifice diameters of air springs on the dynamic performance of vehicle passing curves.The results show that:Analysis of mechanical properties of air springs: The vertical displacement of the air spring is approximately proportional to the load.The vertical stiffness decreases as the angle of the cord decreases,and the lateral stiffness decreases as the angle of the cord increases.The lateral stiffness of the air spring increases with the number of layers of the cord,and the number of layers of the cord has less influence on the vertical stiffness.The transverse stiffness of the air spring decreases with the decrease of the cord angle.When the internal pressure of the rubber bladder is less than 0.15 Mpa,the lateral deformation is obvious.When the internal pressure of the rubber bladder is higher,the lateral deformation is less likely to occur,but if the internal pressure is too large,the internal pressure will be too large.This causes the lateral performance of the air spring to deteriorate.Dynamic analysis of air spring: The lateral stiffness of air spring has little effect on the Sperling index of vehicle lateral stability.The sudden increase of air spring stiffness will cause abrupt changes in lateral acceleration and lateral displacement of the vehicle.Theincrease of stiffness has little effect on vertical stability.The stability index increases as the vertical stiffness of the air spring increases.An increase in the stiffness of the air spring results in an increase in the wheel load shedding rate and creep.Increasing the stiffness when the vehicle passes the curve will increase the derailment coefficient and the wheel load shedding rate.When the air spring frequency ratio is 1,the vehicle system resonates,and the adjustment of the damping has no effect;at that time,the smaller the damping,the stronger the vibration;at that time,the greater the damping,the stronger the vibration,and the excessively high damping will aggravate the vibration.The vibration acceleration amplification decreases with the increase of the frequency ratio.When the excitation frequency increases,the damping effect of the high damping on the vibration decreases,and the low damping gives a better damping effect.The air spring orifice is set at 18mm-22 mm for better stability and comfort.Under the condition of air spring failure,the critical speed of the vehicle is greatly reduced,which seriously affects the running stability of the vehicle.The adhesion of the emergency rubber pile in the low speed range can suppress the shaking action of the frame.As the speed increases,the adhesion is insufficient to restrain the moving head of the frame,resulting in the lateral force of the axle,the wheel load shedding rate,the derailment coefficient,and the ride comfort is deteriorated.The contact surface begins to slip.In the case of failure conditions,the speed should be controlled below 120km/h,and the safe dynamic performance under air spring failure conditions can be obtained.