Study On Nonlinear Mechanical Model And Damping Characteristics Of Steel Spring Damping Rubber Pad For Railway Vehicles

As an important suspension component of rail vehicles,rubber spring has an important impact on the stability,running quality and curving performance of vehicles,which is very difficult to accurately calculate the mechanical properties of rubber spring because of its material nonlinearity,geometric nonlinearity and the complexity of its performance changes after being affected by the environment.With the improvement of the velocity and the requirements of performance,the calculation of its dynamic characteristics is required to be more accurate as well as a specific calculation method of rubber spring mechanical parameters.However,the existing models can't fully meet the application requirements from the standpoint of convenience application and calculation accuracy.Therefore,there is an urgent need for a simple and easy-to-use mechanical model,which can accurately describe the mechanical characteristics of rubber springs with a variety of factors.In view of this situation,on the basis of considering the accuracy and convenience of application,a nonlinear mechanical model of rubber spring is established(XC-Rubber Model),which includes four variable factors: preload,temperature,frequency and amplitude.The application of the model is studied,and the parameter selection method of steel spring damping rubber pad is proposed.In this thesis,the mechanical model of rubber spring is studied in following aspects:(1)A model considering the influence of pre-pressure on the mechanical characteristics of steel spring rubber is established.Taking the steel spring rubber pad as an example,the variation law of static stiffness of steel spring rubber pad with preload is studied.A modified formula of convexity coefficient based on the assumption of elliptic deformation is proposed,and the method of dynamic datum conversion coefficient is further proposed.Through theoretical analysis and experimental verification,the rationality of dynamic reference conversion coefficient method in theory is analyzed.(2)A model considering the influence of temperature on the mechanical characteristics of steel spring rubber is established.Based on the thermodynamic statistical theory,the calculation formula of rubber spring modulus at different temperatures is derived.Based on the modulus at normal temperature,the microstructure parameters in calculation are avoided through conversion.According to the test fitting for the change of modulus under low temperature condition,combined with the modulus calculation method of higher temperature,the modulus calculation formula of steel spring rubber pad in common working temperature range is obtained.Considering the influence of temperature change on the volume,a modified formula for calculating the stiffness of steel spring rubber pad is derived.(3)The coupling effect of vibration frequency and amplitude on mechanical properties of rubber spring is studied.By studying the influence of vibration frequency and amplitude on dynamic stiffness and damping coefficient,the logarithmic function of three parameters is constructed.The influence law of frequency and amplitude on dynamic stiffness can be described by logarithmic function of three parameters,and has high accuracy(The parameters are different).The parameters in compression or shear condition are different,but the difference is very small.The frequency correlation coefficient is proposed in the calculation of damping coefficient,which can well describe the variation law of damping coefficient with frequency,and also provides the basis for the calculation of non-hyperelastic force.(4)The hyperelastic force model and non-hyperelastic force model including preload,temperature,frequency and amplitude are established,uniformly named XC-Rubber model,which includes vertical model and lateral model.The XC rubber model is compared with the calculated values of other models,as well as with the experimental values,proving the effectiveness of the XC rubber model.(5)Based on the non-hyperelastic model(XC-Rubber sub model),the temperature field equation of steel spring rubber pad is established.By analyzing the temperature field of rubber spring,it is proved that the dynamic temperature rise should be considered in train dynamics research.The simulation model of train is established in SIMPACK.Based on the XC-Rubber Model,the relationship between primary steel spring damping rubber pad and vibration characteristics of steel spring is studied,and the method for selecting the parameters of the damping rubber pad is proposed.