Study On The Modeling And Simulation Of Heavy-Duty Truck Steering System And Vehicle Dynamics Analysis

The steering system can affect the dynamic performance of the commercial vehicle. The design and optimization of the steering system is a key technology for the vehicle research and design. This dissertation presents the research on the modeling and simulation of heavy-duty truck steering system and vehicle dynamics analysis, such as the modeling and simulation of the hydraulic power steering system, the three-dimensional CFD (Computational Fluid Dynamics) and FSI (Fluid-Structure Interface) methods to simulation the static and dynamic characteristics of the rotary valve of a hydraulic power steering system, the optimization of the double-axle steering system and the simulation of the heavy truck. The main contents are listed as follows.1) The dissertation presents the modeling and simulation of the hydraulic power steering system. The experiments were carried out to verify the model. The simulation results fit the experiment data very well, and illustrated the correctness of the model. Some design parameter such as the width of the groove, the stiffness of the torsion bar and the gap, etc. are analysed to study the performance of the steering system.2) The three-dimensional CFD (Computational Fluid Dynamics) and FSI (Fluid-Structure Interface) methods are introduced to simulation the static and dynamic characteristics of the rotary valve of a hydraulic power steering system in this dissertation. The power steering curve is derived based on a steady CFD simulation which analyzes the pressure, velocity and cavitation features of the true rotary valve. A full 3D FSI model is constructed to analyze the dynamic response considering the transient fluid and solid interaction. The simulation results indicate that the FSI model will obtain a more accuracy dynamic characteristics of the rotary valve which is assembled in a hydraulic power steering system.3) With design and optimization of the double-axle steering mechanism, a modified steering Ackermann theory considering the wheel slip angle effect is presented to optimize the key point position of steering system. For the double-axle steering mechanism, a detailed multibody model which included the leafspring interfering effect to the steering system is presented. With the detailed multibody model of the steering system the loads in the links are studied, and loads in the links are comparied with different assisted oil cylinder performance. A detailed full vehicle multibody model which including the double-axle steering mechanism is presented, the steering returnability in low-speed cornering is simulated and the uniform loads are acquired on the links. The experiment with double-axle steering mechanism is persented to validate the simulation results.4) The dissertation presents the vehicle dynmics coupling with hydraulic power steering system. The influence of some key parameters such as friction force, damping, inertia, and hydraulic parameters, etc. were studied the analysis the relationship to the vehicle dynamic performance. Analysis of variance and design of experiment are adapted to study the analysis of sensitivity. The on-center, steady state and steering kickback maneuver are carried out the study the vehicle dynamics.