| The concept design is an important part in development process of automotive body, the body's interior, shape and overall performance is determined at the phase of concept design, the structural analysis at the phase of body concept design plays an important role, it provides the practical design projects and avoids some of the problems at phase of the detailed design. The traditional manual design method not only requires designers to master the application software skillfully, but also to do large numbers of repetitive operations, so the efficiency of the design is affected greatly, in order to shorten the development cycle and save development costs, the parametric system that integrates geometric modeling, simulation, optimization as one for the body structure concept design is urgent need.In this paper, the National Natural Science Foundation project "The research on new technology based on the knowledge for the body concept design " (project number: 10802018), the National "863" high tech project " New methods and new technologies for concept car body digital design " (project No.: 2009AA04Z101), FAW innovation projects, " Development and research on concept system for the body structure " (project number: 0838) are subsidized, CAE intelligent analysis system -VCD-ICAE system is developed for the body concept structure design, according to different design needs, the different method of parametric design is used, body CAD modeling, simulation , optimization, output report is integrated into one. In this paper, the following aspects are studied:The re development tools are deeply researched, combining the VCD ICAE system, the design flow of the VCD ICAE system on UG/NX5 platform and implementation method of a variety of design tools is described, it concludes: The method that the VCD ICAE menu is created by UG / OPEN MenuScript and the interface is created by UG / OPEN UIStyler is studied, and the correlation design function of the system is realized by these UF function, but some UF function has not provided,the function seal method is proposed in this paper , the dynamic link library is created and UG external function is transformed to the internal UF function for user. This method expands the UF function greatly. The re development technique has provided the powerful technical support for the system development at future.In view of the automobile body structure concept design for passenger, the automobile body structure concept design system (the VCD-ICAE system) has developed, this system is composed by four modules: CAD modeling module, the finite element pre processes module, the solution and the post processing module, the optimization module. The guide interactive interface is designed by this system, the database is established by EXCEL, the connection between UG and the EXCEL has realized by the UG/Spreadsheet technology, the VCD-ICAE system parameter database is composed by the internal parameter database and exterior parameter database, the data in the parameter database drives the automobile body template, the automobile body template is one kind of complete parameterization model, the creation principle and the creation method of template is researched in this paper. In VCD-ICAE system, the parameterization technology is used for replacing the manual operation completely, and the efficiency of automobile body structure concept design is greatly enhanced. In four modules of this system, the following several questions are researched.In the geometry modeling stage, Adjustment method of beam section direction is researched, the section direction adjustment rule in UG is researched. The relation between the space vector in the FEM model and the plane vector in the PRT file is obtained. The section direction adjustment is controlled by an angle, the section direction adjustment is finished in the geometry modeling stage, this method makes the section direction adjustment is dynamic demonstration and the efficiency of section direction adjustment is greatly enhanced.The stage of finite element pre processes, the quantity of welding unit is great, establishment of the welding unit often spent a lot of time, this welding unit parameterization realization process has researched in VCD-ICAE system, the welding condition is classified according to the welding object, welding style, etc. The parameterization welding method is designed according to the different welding. This method greatly enhances the establishment efficiency of welding unit. The joint is studied. The joint is simulated by torsion spring and rigid beam. The parameterized joint is realized.In the post processing stage, the method that XML language creates output report is studied, this report format is set by the XSL, the data in VCD-ICAE system data structure is taken as outer parameters and the parameterization result report is realized automatically. In the optimization stage, the automobile body model corresponds to a number of sections, each section corresponds to a number of cross section line, therefore, owing to too many design variables, the optimization process is often inconvenience when cross section is optimized, this paper presents a cross section line classification and cross section re build method. The so called section line classification method is that section lines according to the type of panel are classified, and update data according to"class". The so called cross section re build method is that the change of thickness and shape is saved in data structure in the form of parameter when each iteration, and it replaces the last result, when the cross section information is updated, it need not look for which design variable is changed, while the previous section is directly removed and the new cross section is reconstruction according to the new data structure. The application of these two methods realizes optimization of multiple cross sections at the stage of concept design. It makes the calculation results more instructive and greatly improves the efficiency of optimization.In order to test the VCD-ICAE system feasible, the bending stiffness, torsion stiffness and modal of a certain car detailed model is calculated, The joints of concept model are simulated by spring element and rigid beam element, and stiffness of joins are calculated. The beam sections are collected and the sections are simplified. The results are calculated by VCD-ICAE and are compared with detailed model. The results show that result of concept model can predict the results of detailed result with some accuracy and it tests the VCD-ICAE system feasible.In order to manage cross section of the beam better, the beam cross section database management system (SMS system) is developed. The system also can design and analysis cross section. In this system, a detailed cross section is designed by the expression parameter, and expression is extracted and embedded in the database by UG / spreadsheet. It realizes the parameter design of cross section. In addition, cross section of the optimization method has been studied in the paper. It concludes the thickness optimization method; Offset Optimization; Scale Vector optimization method. Comprehensive utilization of these methods has been optimized for a certain sections. The development of system makes the management of cross section more convenient and realizes CAD data and CAE data integration.The concept"body detailed concept model"is proposed and the characteristics of body detailed concept model is analyzed, it focuses on the modeling method that transition area between the panel structure, this method takes the sections as study object, the endpoint sorting, vector sorting, angle comparison, the head and tail corresponding as well as the cross section line grouping. A range of methods achieves the automatic creation of the bridge curves and, the edges of the edge transition surface and edges of center of the transition surface is determined by endpoint index number. This method improves the efficiency of modeling greatly.
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