| In order to solve the problems of energy shortage and environment pollution, widespread application of the developing electric vehicles has become a hot research topic among the major automobile companies. Our research group creatively develops the electric vehicle with plastic body in the experiment base of Ningbo GMF Technology Ltd. We apply rotary plastic molding technology to the electric vehicle, which breaks through the plastic manufacturing key technology. And the body is integral processed by linear low density polyethylene plastics. In addition, the safety vehicle structure design is one of the key contents of the body crashworthiness properties. Although this technology has broken through the technical bottleneck of light-weight of car body, compared with metal car body, the plastic body has the weak material strength and the poor collision energy absorption ability in terms of the collision safety performance. Therefore, how to design a reasonable and effective structure to improve the crashworthiness of the electric vehicle with the plastic body is the core problem.According to the collision regulations, this paper takes 100% rigid wall frontal collision structure of the electric car with plastic body as the research object to analyze the crashworthiness. And the numerical simulation is carried out by using the finite element analysis software LS-DYNA. The main work and achievements as follows:1、By using the reverse design method and reverse engineering software Geomagic studio, this paper takes one of the electric vehicles in the market as the benchmarking car, in order to reconstruct the three-dimensional model of the benchmarking automobile. Then, on the basis of this model, three-dimensional modeling software UG is applied to design the three-dimensional model of the electric vehicle with the plastic body.2、At first, according to the finite element theory of the collision simulation, the paper introduces the basic algorithm of LS-DYNA software. The second, based on the frontal impact regulations in the GB11551-2003 "Passenger Car Frontal Impact Occupant Protection", the front crash finite element model of the plastic body of the electric vehicle is established by the pre-processing software Hypermesh.3、The finite element model is submitted to the LS-DYNA solver and the reliability of the results is analyzed. The analysis results show that the collision energy is mainly absorbed by the plastic body of the electric vehicles. What is more, because the deformation of the front longitudinal beam of metal skeleton is small, the battery packs are protected. At the same time, there are some issues to be solved. For example, the plastic material strength of the body structure is weak, the car body stiffness is large, and the impact energy absorption ability of the plastic body needs to be enhanced.4, Because of the weak strength of the body structure material, the large car body stiffness, the poor impact energy absorption ability of the plastic body, this paper puts forward a vehicle body optimization design that polyurethane foams are filled in the plastic body. Besides, the design is combined with the body processing rotary molding technology. As there are different kinds of polyurethane foam, the collision models of soft polyurethane foam filled in the body and rigid polyurethane foam filled in the body are established in the paper. Then the Crashworthiness of the body structure before and after optimization is comprised. We come to the conclusion that it is feasibility and effectiveness of the optimization solution. At the same time, the two kinds of the optimization schemes are also compared. According to the results, the conclusion is that the optimized material type of polyurethane foam is soft polyurethane. |
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