Study On Concept Design And Optimization Of Car Body Based On Frontal Impact Crashworthiness

With the gradually improvement of the level of automotive design, car companiesurgently need to shorten design cycles and rapidly intruduct the new car models, in order toseize market segments to obtain greater profits. As one of the four assembly of car, car bodyis the main carrier to guarantee the performance of car and an important part of car design.Concept design phase played a more and more important role in modern automotive design.So the study of how can ensure the performance of car body in the concept design stage mustbe of important significance. Structural crashworthiness is one of the main indicators toevaluate the safety performance of a new car. It is very deficult to design in the detaileddesign stage, because there is not enough room to modify the structure. So how to considerthe crashworthiness performance in the conceptual design stage is of great significance toimprove the performance of the car and shorten the design cycles.This paper presents both the process of reverse and positive concept design of car body.The key technologies of reverse concept design was described in detail, which contains theestablishment of simplified joint model, the simulation of beam-like component and theextraction of the stiffness characteristics. By comparing the simplified model and detailedmodel of the bending and torsional stiffness characteristics, the validation of the simplifiedmodel was varified. Frontal impact simulation with the same boundary conditions comparedwith detailed model was conducted based on the varified model. Then the results werecompared with the detailed model, where can we find the way to improve the simulationaccuracy of the simplified model. A process of positive concept design was proposedinnovatively. First, the optimal structure layout of car body was finded out through topologyoptimization techniques. Second, a simplified beam element model with regular section wasbuilt to quickly verify the validity of the topology structure. Then, considering quasi-staticload conditions, the size of beam cross-section was optimized to obtain the initial size of themain components of car body except front rails, which is the basis of frontal impactsimulation. Ultimately, the optimum design of straight thin-walled beams for crashworthinessanalysis was studied to explore the methods of crashworthiness concept design. Ultimately,the crashworthiness concept design of straight thin-walled beams was studied. Proposed anew method of using the response surfacing approximation model to establish the non-linearrelationship between the cross-section parameters of thin-walled beam and its stiffnesscharacteristic curve points, which can be the bridge of crashworthiness optimization todirectly optimize the thin-walled beams in concept design stage, and finally received the primary size of the car body, which will be used in the process of detailed design.The results show that: A high-precision simplified beam element model can beestablished through an appropriate method, and it is easy to be used as the object of the studyin the early phase of conceptual design to optimize the design. A process of positive conceptdesign of car body was proposed, which provides a good idea to the design of car bodystructure. it is easy to find the direction of the optimal design. The method of making theresponse surface approximation model as the design bridge is a good solution to solve theproblem of the concept optimum design of thin-walled components.This study provides some reference for the domestic automotive enterprises to carry outthe conceptual design work, and opens up a new way of thinking to improve our own autodesign capability.