Studing On The Designing Methods Of The Structures Of Vehicle Bodys Depending On The Advanced Theories

Modern vehicle body plays a very important part in the vehicle's performance. The individual characters of vehicles can be showed through the bodies. The overall objective of this study is to study dynamic characters of bodies and the stiffness characteristic of Tires and static by the means of modern theories and methods of design.The thin wall sections which shapes are very complicate is divided into finite segments. The coordinate axes are built to describe the shapes by the values of the key points. The formulas which can be used to calculate the geometric parameters of the sections easily and accurately are carried out depending on the theory of integral and analytic geometry. The sections' center position of figure, twist and flexure are fixed precisely. The moment of inertia can be calculated precisely. The practice indicated that this development can contribute to the shape optimization of the thin sections by changing the positions of the notes. The practice indicated that this development can contribute to the shape optimization of the thin wall sections by changing the positions of the key points.The geometric model of the vehicle body is built in Unigraphics software and then is introduced to ANSYS software. Theoretic strength analysis of the body frame was carried out by using ANSYS software. The effects of all the parts on the stiffness of the bus body are discussed. The mechanical characteristics of the rectangular sections which are widely used in buses are given. The method is given to adjust the stiffness of some parts to make them suitable as a whole. Theoretical and experimental results of both improved and original bus body are discussed and commented on. The corresponding experiment was also conductedThe simulation method is studied to calculate dynamic stress of the vehicle body caused by the uneven road. Taking account of the complex nature of tires, the vehicle is divided into two parts which are upon and under the suspensions to avoiding the errors caused by the simplified tires. The system being studied is the part upon the suspensions. The input of the system is the dynamic load translated from axles to suspensions and the output is the dynamic responses of vehicle body. The Equations of vibration of the system are derived. The formulas are got on the basis of the theory of elastic mechanics.It is developed that the cornering force characteristics of tires may be got by researching the micro-deflection of tires. Based on the three suppositions about the motion of tires, the relationship between the cornering force characteristics and the micro-deflection of tires is built. A detailed finite element model of a radial tire is constructed for the prediction of stiffness characteristics by using ANSYS software. The nonlinear mechanical properties of the elastomer were modeled by the Mooner-Rivilin model. A example of the radial tire (185/60R1482H) is given. The calculated results are compared with the experimental results and it is showed that the model reliability is fairly good.The flexible foundation effects on isolation performance of engine-mount systems are discussed. Depending on the theory of modal analysis of vehicle body, equations of vibration for the engine-mount systems, which include engine-mount systems, flexible chassis and suspensions, are derived. The isolation performance of engine-mount systems mounted on the flexiblefoundations is studied by use of Four-End parameters method. It is shown that the flexibility of the foundations has significant effect on the dynamic responses of engine-mount systems especially near the natural frequencies of the supporting structures.The Frame of the Container Semi-dragging Truck is taken to be as an example because of its simple structure and load. The optimal theory of both topology and parameters is introduced into the design of continuum structures to obtain better designs of structures. The procedure can be briefly described as three stages. The first is to get a primal structure depending on the theory of topology. The second is to build a functional structure which is satisfied with the technological requirements. In the final stage the optimal structure of the frame is got depending on the parametric optimization. The optimal design of the frame of a container semi-dragging truck is carries out by means of ANS YS software. The process of it is described in detail. The problem of determining the original structure of the frame is considered. According to result of the topology optimization of the frame the optimal structure of the frame is got depending on the parametric optimization. The comprehensive application of the optimal and parameters theory in the automobile structure design is realized. The dual exploitation of ANSYS software is done by using the languages of ANSYS (APDL and UIDL).