附 錄The skeleton of a wingspan van body is one of the most important components for a van. Its weight is about one third of the whole vehicle gross mass. The weight lightening of skeletons is of great importance to reduce the vehicle weight. This dissertation seeks feasible methods for the lightened skeleton of a van body through FEM (finite element method) analysis on the skeleton of a wingspan vans body. FEA has become one of the most important tools in modern automobile design. Compared with traditional methods, its advantages lie in improving the quality of auto products, reducing the cost of product-developing and production, and increasing the competition of auto products in the market. In order to improve the level of van body designing and guarantee the competition of designed vehicles in the market, we must heighten the FEA technique of the van body to a strategic level. Van, as a fuel-consuming vehicle, is attached great importance in regards to its fuel-saving level which is directly connected with the energy consumption of our whole country. Due to this great significance, van manufacturers all over the world try their best to lighten the weight of vans. The technique of weight-lightening design has become one of the hot techniques in the research field. Since the exploitation condition of van is extremely bad, and stress condition is complex, the skeleton should have enough rigidity so as to keep the relative positions of some parts unchanged and the change of the van body shall be limited to a minimum degree while the van goes. There also should be enough intensity in the skeleton so as to ensure its reliability and life-span. The insufficient skeleton rigidity not only causes vibration and noise, but also makes the ease of driving, the stability of operation and the reliability of some parts decline too. Therefore, how to design light-weighted skeletons that meet consumers requirements becomes a challenging job. The skeleton of a wingspan vans body is analyzed and studied by the ANSYS in this paper. The static intensity and rigidity of the skeleton is analyzed and studied in the instances of pure bending, coupled bending and torsion, braking condition and sharp-turning. The results indicate that the stress of the skeleton is less than the utmost intensity that the material being used has to resist. There is little displacement in the skeleton and it meets the demand of the design. This paper also deals with the dynamic analysis of van skeletons with mode analysis as a main part, which is the core of the dynamic configuration design. It overcomes the shortcoming of the static analysis and emphasized that the problem should be considered from the whole configuration. The local intensity can be learned through the vibration model and the responding frequency of the skeleton which are obtained from the model analysis. Amelioration design can be done with various optimization methods. In the research, a conclusion is drawn that the optimization module of ANSYS is not applicable for the whole skeleton of van body, because the skeleton has too many stems and dimension. According to the characteristics of the skeleton, several schemes used to design lightened skeletons are proposed in this essay. Some components of little influence on the intensity and rigidity are subject to direct amelioration, and some sensitive components are to the repeated calculations under different conditions for the best optimizing design. This research had done a large number of calculations in different conditions for different stems. The final results show that this combined method is feasible. The weight of the skeleton of the designed van body is reduced by 95.8Kg. Finally, with the statistic from the stems and the dimensions of the skeleton as variables for designing and with the whole volume of the skeleton as the goal, this essay makes a preliminary discussion of the weight-lightening of the structure of skeleton using ANSYS optimizing model. Optimized results make the skeleton light, save raw materials, reduce the cost of manufacture, decrease the fuel consumption and do no destruction to the environment. The research in the essay demonstrates that FEA and ANSYS offer excellent basic theories and methods for the skeleton structure, simulation of power characteristics and weight-lightening design. They have very important project values in weight-lightening designing of the skeleton structure.