Finite Element Analysis And Lightweight Design Of Electric Passenger Car

With the promotion of new energy vehicle in our contry, more and more automobile companies are beginning to produce the electric vehicle. Compared with the traditional internal-combustion engine vehicle, the ordinary electric vehicle has much difference in performance and price. Therefore, the low-speed electric car based on the utility has developed rapidly in recent years. The majority of the low-speed electric cars are restructed from traditional automobile. Body material is redundant to basic performance. In order to further improve the storage mileage, the lightweight design of body has great significance.A low-speed electric passenger car was taken as the research object, whose finite element model for static and dynamic analysis was established. The stiffness analysis, modal analysis and strength analysis based on the finite element model of BIW were conducted. The values of bending stiffness and torsional stiffness, low order natural frequency and vibration mode figures, stress nephogram of the body in bending-torsion condition were got respectively.For the strength analysis result, a lightweight design method of car body based on static strength was proposed. The parts yield stress values were taken as constraint condition. The total mass minimization of all the parts was taken as objective function. After the optimization process, stress values of parts were close to their yield limits respectively by using one-dimensional search method. The utilization ratios of materials were also improved.The front 100% rigid barrier impact finite element model and front 40% deformable barrier impact finite element model of low-speed electric passenger car were built, then the validity of impact models were confirmed by analysing the energy curves and deformation sequence diagrams. The part deformation figures and the dummy injury values were extracted, and then the deformation modes and the dummy injury curves were analyzed.According to the results of front impact, a lightweight design method of car body based on frontal impact was put forward. The dummy injury values were regarded as constraint condition. The mass minimization of the parts was regarded as objective function. The parts thickness was regarded as design variable. Finially, the optimal combination of parts thickness was quickly achieved by using the relative difference quotient algorithm.