| During the forward design process for new automobile, traditional method is serial, which is building detailed CAD model first. Then use the established model to go on with CAE analysis. Change and correct the original CAD model according to the analyzing result, then repeat the CAE analysis. Go on with this design loop until the analyzing result matches the structure design requirement. So the whole design cycle is time consuming. To maximum decrease the time used to correct body structure of automobile during the forward design process, consider the structure performance during the first concept design phase is meaningful, and engineer can finish about 60% analysis work in this phase, matching the idea of structure performance analyzing guide structure design. However, the research on positive structure design of automobile according to performance analysis in domestic is relatively fewer. In this article, based on parameterization and modular theory of automobile body structure, builds the parameterized half BIW structure for front collision research analysis. And use the collision safety performance to guide the structure optimization of front-bumper and crash-box. The detailed research content is as follows:1)Research the influence of main energy absorbing part of automobile in front collision, including front-bumper, crash-box and side-rail. Conclude and pick up main structure parameters which have important influence on front collision performance, including shape, size and material. And use these parameters in the process of building parameterized CAD models.2)Establish the parameterized model of various parts of half body structure for front collision analysis. Prove the evaluation of parameterized half body structure by comparing the collision result of half part CAE model and real whole car crash experiment. Divide the whole BIW structure into several modular parts depending on the dividing theory and parameterization theory. And construct the modular design information library, assembling the whole BIW structure successfully by picking several modular structure part.3)Build the versatility structure-optimization-platform. Successfully divide and assemble the collision analysis document for CAE caculating by special model setting. This platform can change CAD models automatically according to the setting data of design parameters from structure engineer. It will call material parameters from material library, or change these parameterization for deformable solder point. This platform also can finish analysis calculation of true CAE models, realizing the combine optimization including shape, size and material.4)First of all, record the geometric and material parameters of front-bumper and crash-box. Then filter the various parameters and set the variable range through sensitive analysis. Optimize the original modular structure by using the platform built before with the constraint of total energy absorbing and the design goal of minimum peak acceleration and minimum weight. In this article, finally reduce the peak acceleration about 40.8% and decrease weight about 34.8% at the same time.5)In this article, to match the optimization goal of low cost and few caculation, do research on how to fit high quality approximation model with few sample point. Depending on the judgment of the maximum Euclid distance with RBF approximation model, add correcting point into the original sample point to modify approximation model step by step. And use NSGA-II method to excute multi-optimization and get series of Pareto reference data for engineer to choose.Based on implicit parameterized modeling method with the software of SFE CONCEPT, design the modular structure part of BIW. Realize the construction of versatility structure optimization platform through dividing and assemblying analysis data. Record the parameters and use the combined optimization method greatly increase the collision performance and realize the lightening goal. |
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