Research On Frequency Variation Characteristics And Structure Optimization Design Of Rail Vehicle Hydraulic Rubber Joint

As the core suspension component,the characteristic parameters of rail vehicles hydraulic damping system will directly affect the vehicles operation quality.The deterioration of dynamic performance is generally related to the mismatch of wheel-rail contact status and suspension parameters.Different excitation frequencies should select different suspension parameters to meet the requirements of train stability and stability.At present,the suspension system of rail vehicles is mostly passive;the shock absorber and series rubber joints generally do not have frequency dependent parameter characteristics.This thesis embarks from the contradiction that the fixed stiffness of anti-snake damper cannot take into account the lateral stability under different wheel-rail contact equivalent tapers,a hydraulic rubber joint with frequency dependent parameter characteristics which installed at the damper connection is proposed.In this thesis,the study of rubber joints with frequency dependent parameter characteristics is meaningful.The main results are summarized as follows:Firstly,the internal structure and hysteresis principle of hydraulic rubber joint are introduced in detail.Direct method is used to conduct the two-way fluid structure interaction finite element transient analysis.The finite element models of solid structure and liquid structure are established,they are linked through the fluid structure interaction boundary conditions.Combined with the rubber experimental,the mechanical behavior of rubber is described based on Mooney-Rivlin hyperelastic material constitutive model,which provides material parameters for finite element simulation.Secondly,the static stiffness,dynamic stiffness and damping lag angle are used as evaluation indexes to analyze the mechanical properties of hydraulic rubber joint.The results show that,a)under slow loading,the static stiffness of hydraulic rubber joint has little correlation with radial displacement,and the liquid cavity volume has a certain influence on the stiffness value.b)Under sinusoidal excitation,the hydraulic rubber joint exhibits frequency dependent parameter characteristics that low stiffness with low frequency,and high stiffness with high frequency.With the increase of excitation frequency,the lag angle increases rapidly and decreases slowly after reaching the peak.c)Pre-compression has no significant effect on the dynamic characteristics.Increasing the liquid cavity volume,reducing the cross-sectional area and the number of channel,increasing the channel length or increasing the fluid viscosity can effectively improve the dynamic stiffness magnification and reduce the excitation frequency corresponding to the peak lag angle.Increasing the rubber hardness will lead to an increase in static stiffness,but a decrease in dynamic stiffness magnification.d)In order to ensure the reliability during service,the mechanical behavior of hydraulic rubber joints under two failure conditions of internal liquid leakage and channel blockage is discussed.Thirdly,the design of hydraulic rubber joint is optimized from the structural parameters and material properties.The vulcanized rubber with Shore’s hardness of 63 HA and the dimethyl silicone oil with dynamic viscosity of 200 m Pa·s are selected,and the U-shaped circuitous flow channel structure is adopted.The static stiffness of the optimized hydraulic rubber joint is 12 k N/mm,and the dynamic stiffness at 10 Hz is 48 k N/mm.The dynamic stiffness is increased by 4 times.The peak lag angle is about 36.8° around 0.7 Hz.The damping coefficient tends to be stable after the excitation frequency is 0.7 Hz,which is about7.1 k N.s/mm.The optimized hydraulic rubber joint is more suitable for the use of rail vehicles.Finally,the lumped parameter model,the equivalent mechanical model and the spring damping integer-order model are built to analyze the characteristic parameters of the hydraulic rubber joint in theory.The Poynting-Thomson model theoretical expressions of the dynamic stiffness and damping lag angle are derived in detail.The theoretical values are highly consistent with the fluid structure interaction finite element simulation results.The results show that the Poynting-Thomson model can accurately fit the dynamic characteristics of hydraulic rubber joint,and the fluid structure interaction finite element analysis method described in this thesis is exact.This thesis provides a feasible method for introducing the new rubber joint with frequency dependent parameter characteristics into the vehicle system dynamics calculation.In conclusion,the research results of this thesis have guiding significance for the research and development,theoretical analysis,simulation calculation and experimental verification of hydraulic rubber joints,and also have reference significance for the application of elastic rubber & viscous liquid composite vibration reduction technology in rail vehicles.