Design Optimization Of Rhombus Vehicle Suspension And Vehicle Dynamics Analysis

This dessertation makes the design and analysis on the middle suspension based on the rhombus vehicle. Since the rhombus vehicle has the advantage of good collision safety and small turning radius, there is strong engineering and scientific research value for it. This paper is mainly focus on the design in suspension system, and also carrying out the whole vehicle experiments to identify the feasibility and reasonableness of the design. As to the driving wheel middle layout, we took a variety of methods to decrease the vertical dimension of suspension system to avoid to decrease of useful space which was caused by the protruding of the middle part of the cab so that the structure and disposition of the rhombus vehicle can be most actualized. Investigation to roll and brake conditions of the rhombus vehicle, the dissertation also presents the brake methods of the rhombus vehicle. Finally, the rhombus vehicle was detailedly experimented in the dissertation. Experimental results was satisfied to reach to experimental standard established by countryIn the design of guiding components, considering that the double wishbone suspension system has the advantage of small vertical dimension, we chose it. Meanwhile, we also opimizated the structure through the genetic algorithm and the softwares of ADAMS and MATLAB and determined the space position of hardpoint and length dimension of each guiding components. At the same time, we constructed three-dimensional model of the guiding components.In the design and analysis of elastic components, a detailed calculation about the choice of torsion bars was made in the paper; a relatively thorough analysis about the design of the leaf spring was carried out, and a variety of calculation methods, such as common curvature method, concentrated load method and improved concentrated load method, are applied to the calculation of the stiffness, length, and stress of leaf spring, and a comparison between them is made, especially on the stiffness of leaf spring when it is installed transversally. The leaf spring structure is finally chosen to be the elastic elements of middle suspension based on the comparison between torsion bar and leaf spring as well as the requirements for variable stiffness of the suspension and the structure of the rhombus vehicle. Because the main reason for failure of elastic components is fatigue, a discussion on fatigue of the leaf spring is made. Also, since unstable variable stress is endured by the leaf spring, a precise fatigue calculation on the leaf spring of rhombus is made using the Fatigue Accumulation Damage theory.Design to damp elements, according to analysis of the vehicle ride, the damp characteristic curve of the middle suspension rhombus vehicle in order to provide bassis for calculating damp elements. Through analysis and design for the tube shock absorber, the all kinds of parameters and mathematical model were determined. In order to descrease vertical size, the torsion shock absorber was applied to middle suspension. Using the idea of the damp moment of the torsion shock absorber to be equal to the damp force of the tube shock absorber, the equivalent relations of the tube shock absorber and torsion shock absorber was presented. The design parameters and layout methods of the torsion shock absorber were determined.The brake and roll conditions are mainly investigated in vehicle dynamics. The dissertation detailed analyzed the roll and brake conditions of the rhombus vehicle. The load transfer of the roll condition and brake methods of the rhombus vehicle were simulated with Matlab/simulink software. The simulation result were compared and analyzed to obtain the brake methods of the rhombus vehicle. The brake methods establish basis for optimizing design brake system of the rhombus vehicle.We took series of experiments on rhombus-vehicles. The 7 experiments focused on the handling and ride characteristics of rhombus vehicles. Through these experiments, we proved that rhombus vehicles have the similar performance in the handling stability and ride with the ordinary layout cars.This paper originally presented a kind of suspension system which consisted of the double wishbone suspension as guiding components, leaf spring as elastic component and torsion shock absorber as damp components. According to comparison the simulation analysis and the experiments results, we proved that the design of this paper to the middle-set suspension of rhombus vehicle is feasible. Finally, the dissertation firstly analyzed the roll and brake conditions of the rhombus vehicle and present brake methods of the rhombus vehicle...