Analysis Of Vehicle Vibration Character Of The Piecewise-linear Suspension System

With the rapid development of railway in China, there are continuously increasing new requirements regarding riding comfort, running safety, and speed of railway vehicles. The suspension systems are considered as an important way to deliver force, motion and support the vehicle, so the choice of its design parameters will affect the quality of the dynamic performance of the vehicle. Therefore, the study of vehicle suspension system have a great of significance. This thesis is based on piecewise-linear vehicle systems, the vibration characteristics of the vehicle system is studied. The main research contents are as follows.In the first chapter, the history of railway and development of high-speed railway situation are elaborated, and the background, significance and research status of vehicle suspension system are intruduced briefly, and the main work is illustrated at the end of the chapter as well.In the second chapter, the contents and classifications of the vehicle suspension system are introduced, and as well the nonlinear character and control methods of the suspension system are stated.In the third chapter, a single-degree-of-freedom spring and damper model of piecewise linear vehicle vertical dynamic suspension system is established, The excitation from the track surface is considered as a sine curve. The dynamic differential equations are listed, then using the averaging method to calculate the amplitude-frequency response function, after that,getting the amplitude-frequency response curve. The influence of various parameters on the amplitude-frequency curve is analyzed, then numerical simulation on this suspension system is conducted. The bifurcation point of exciting frequency are found. The research shows that the system is in a periodic or quasi-periodic motions, will not be in chaos. The conclusion reveals that amplitude frequency will appear nonlinear characteristics or not depends on the size relationship between excitation amplitude and piecewise clearance.In the fourth chapter, a two-degree-of-freedom piceewise-linear model of vehicle suspension system is established, and the dynamic differential equations are listed. Then the averaging method is used to calculate the amplitude-frequency response function of this system, from the application of Matlab program to get the amplitude-frequency response curve. The results shows that the system will have linear characteristics when the spring clearance is less than the amplitude of the excitation, on the contrary, the curve will appear a jump phenomenon. Analysising the influence on the curve in view of the various parameters,and studying the riding comfort and running safety of the vehicle.In the fifth chapter, a two-degree-of-freedom piecewise-linear suspension system modelis set up using Matlab/Simulink. The simulation analysis is used to this model, then the time domain are derived on the six track spectrum of the United States. The dynamic response under the six track spectrum of the United States is analyzed.In the last, summing up the complete content and further prospect.