Analysis Of Frequency-stiffness Properties Of Primary Suspension Rubber Joint In Bogie Of High-speed EMU And Its Influences

Rubber joint is an important connection component between tumbler journal box and bogie frame in railway vehicles. It is widely used in subway vehicles, light rail vehicles and high-speed trains. It undertakes some important functions, such as transferring the longitudinal force of traction or braking, ensuring the stable operation of the train, therefore optimization of rubber joint parameters is quite important in dynamics analysis of bogie. When rubber joint is used in subway vehicles, the typical case is lower speed and smaller radius, lower track level than passenger dedicated line, and lower vibration frequency range, so the influence of curve negotiation performance is always considered in optimization of rubber joint parameters. When rubber joint is used in high-speed EMU, with the speed350-380km/h and curve radius more than5000meters, the stability of high-speed train and problems sensitive to parameters are always taken into consideration in optimization of rubber joint parameters. In spite of its high track regularity and small vibration variance, the overall vibration frequency range is wider, so dynamic stiffness of rubber components and its influences which are neglected in past researches become more prominent. Therefore, the thesis analyzes tumbler journal box positioning structure of EMU, and then further analyzes the influences of frequency-stiffness properties of rubber joint on dynamic performance of high-speed EMU through calculation of stiffness and dynamic simulation.This paper includes the following four aspects.(1) Analysis of rubber material constitutive model. Two research methods of rubber material constitutive model are introduced, and the typical models based on continuous media phenomenological description, i.e. hyperelastic model, viscoelastic model and the elastic-plastic model are discussed. Analysis of how to obtain parameters of different rubber hyperelastic constitutive models by experiment provides theoretic basis for establishing finite element overlay model and studying dynamic properties of rubber joint (chapter2).(2) Establishing rubber joint finite element model and suggesting the method of parameter identification. Dynamic properties of rubber joint are investigated through harmonic shear test. Meanwhile, the discrete stiffness of rubber joint is calculated by finite element method of overlay model, and validated through test. Then rubber joint frequency-stiffness curve in different amplitudes is drawn based on the discrete points, and ultimately its frequency-stiffness curve and amplitude-stiffness curve. Identification method of material experimental parameters of rubber joint is put forward, to identify plastic material parameters and viscous material parameters (chapter3).(3) Starting from single freedom system, establishing quality-spring dynamic model, and analyzing the response of frequency-stiffness properties of spring on mechanical vibration system. The influence of frequency-stiffness properties is taken into consideration in dynamic calculation. The modeling process of frequency-stiffness force element in vehicle multibody dynamics software SIMPACK is introduced (chapter4).(4) With a given CRH high-speed EMU as the research object, a traditional dynamic model without considering frequency-stiffness properties and a dynamic model considering frequency-stiffness properties are established. Vibration modal and critical train speed in the two models are analyzed through comparison. Viberation frequency of connection components, the deformation and stress distribution range of rubber joint in the traditional model are analyzed as a basis for introducing a dynamic model which considers frequency-stiffness properties of rubber joint. Through comparison of the two models, the influence of frequency-stiffness of rubber joint on dynamic performance of high-speed EMU is analyzed in detail (chapter5).This paper adopts the finite element method of overlay model to describe dynamic mechanical behavior of rubber joint in practical engineering application environment, providing a new method to analyze dynamic stiffness of rubber components. With a given high-speed EMU, a vehicle dynamic model which considers frequency-stiffness properties curve of rubber joint is established to study the influence of frequency-stiffness of rubber joint on dynamic performance of EMU. The paper can serve as a foundation for further analysis of dynamic performance of high-speed EMU and parameter sensitivity, and also as a basis for optimization of parameter design of high-speed EMU rubber joint.Some important conclusions are drawn from this research:1) Dynamic properties of rubber joint in primary suspension of EMU can be calculated by the finite element method of overlay model. The experimental result indicates that the method has better accuracy. For the experiment and calculation of the sample rubber joint in this research, the relative error is less than5%;2) Frequency-stiffness properties of rubber joint have a major influence on dynamic performance of EMU. As far as the research object is concerned, its nonlinear stability critical speed is6.25%lower than the traditional calculation; When the train speed is more than250km/h, axle transverse force grows more obviously with rising speed than the traditional model; when the speed is350km/h, the axle transverse force of leading wheelsets grows about22%more than the traditional model; it has less influence on vertical stability of the vehicle, but the influence on lateral stability is more obvious than the traditional model with the speed more than250km/h. When the speed reaches350km/h, Sperling lateral stability index of the two models are2.63and2.52respectively.The innovation of this paper is reflected in the following two aspects:1) Frequency-stiffness properties of rubber joint are introduced into dynamic calculation of high-speed EMU, and its influence on vehicles is analyzed with a specific model EMU.2) It is proposed that frequency-stiffness properties of rubber joint can be calculated by the finite element method of overlay model. And it is carried out through experiment.