| Steering Gear transmission is widely used in mechanical structures and plays an important role in various transmission systems.Dynamic analysis of steering gear systems is essential in describing vibration and durability characteristics,and,based on this,to design a transmission system with high stability and efficiency.This thesis investigates the dynamic behavior of a steering system with several backlashes and a feed screw-nut structure.The main work can be summarized as the following four parts.1.The equations of motion of a 3 degree-of-freedom dimensionless system were established,considering the influences of the backlashes of between the components,transmission error excitation and time-varying mesh stiffness.Basic parameters of the system are valued based on measurement and the finite element calculation for a actual system.2.The harmonic balance method based on Fourier transformation and the RungeKutta method were adopted to solve the equations of motion of the steering system,to describe the dynamical behaviours.3.Modal analysis was used to analyze the natural frequencies and amplitudefrequency spectrum of the system with both harmonic balance method and theoretical method to obtain the amplitude frequency characteristic of the system.Then,the system was also numerically solved by Runge-Kutta method and bifurcation,chaos and other complex dynamic phenomena were presented.Analysis of the dynamic transmission error and dynamic meshing state was also presented.Finally,the response characteristics of the system are given by the non-steady state analysis.4.Influences of gear backlashes and other parameters on dynamics of the system were analyzed,for example,the position of the backlash and the value of load,backlash,and damping.The result of the paper indicates that both the operating conditions and the structural parameters of the steering gear system can be designed properly to avoid undesirable dynamic motion and realize better mechanical properties. |
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