Research On Crashworthy Frame Structures Crashworthiness Topology Optimization Design Of Electric Vehicle Body

With the increasing demand of vehicle for Chinese consumers, automobile ownership in China is increasing, with the traffic accidents due to increased car ownership are also increasing. The attention and recognition on vehicle crash safety performance among the public are increasingly improved. The vehicle's safety performance equivalent to comfort and dynamic economy has also became one of the key considerations when people purchase cars. In order to meet not only the safety laws and regulations as well as the existing national C-NCAP star rating index, but also the safety demand of extensive consumers, automobile manufactures were forced continuously improve the structural design of the vehicle crash safety. In the concept phase of automobiles development, topology optimization methods for the design of the body structure, combined with engineering knowledge of typical cross-section design, can effectively identify the best collision load path in a short time, and contribute to the vehicle's crash safety performance improvement.To solve the issue crashworthiness topology optimization of automobile body, this paper discussed the crashworthiness topology optimization method base on LS-DYNA explicit FEM. In my proposed method, Hybrid Cellular Automaton was taken as computational model. The finite element method was used to do structure analysis to obtain iteration information in the process of optimization, and the local change in the design variable was determined by local control rules. In topology domain two connected subdomains were defined:a flexible subdomain and a stiff subdomain with constraint of different design dimensions and mass fraction to control structure energy absorption and distribution. Then applied the method in the topology optimization on single load case and multiple load case, compared the research results with the results based on traditional method. It turned out that this method can reduce the collision force and improve structural crashworthiness in the process of collision.Furthermore this article based on actual project, took a bumper-like design of a electric vehicle as the research object, by the structure crashworthiness optimization through a nonlinear collision conditions. Then carried on low-speed pendulum impact simulation and low-speed trolley impact simulation of the improved structure compared with the results in literature to verify the feasibility and accuracy of this approach. As to the battery box structure design of a electric vehicle on the drawing board, we applied the crashworthiness topology optimization method and also considered the static characteristics of the battery box in the vehicle actual development process. Both the dynamic and static characteristics were regarded as the conditions of topology optimization. Compared with traditional topology optimization design which can only consider a single static or dynamic optimization, in this article the optimization results through multi-objective optimization were more close to the actual working condition and has a guiding significance. The results showed that the mode analysis results and crashworthiness analysis results of the improved battery box structure were better than the original structure, and the body weight were reduced by 8%.The present paper proposed a new crashworthy topology optimization method based on theory and practical engineering need. Research results showed that the method can be able to get a good safety performance as well as meet lightweight design requirements in the process of automobile development. In this way, we can reduce the development cost and shorten the development cycle.