Structure Analysis And Optimization Of Electric Vehicle Considering Collision Safety

With the intensification of environmental pollution and the shortage of energy resources,electric vehicles have gradually entered people’s vision with their advantages of zero emissions,zero pollution and renewable electricity.The collision safety of electric vehicles is always one of the focuses of people’s attention.The battery pack is the source of power for electric vehicles.The battery pack system may suffer fire,explosion,short circuit and other phenomena when the electric vehicle suffer a collision.When researching and designing the structure of electric vehicles,it is necessary to consider the collision safety performance of the vehicle,especially the safety performance of the battery pack.This paper takes an electric vehicle modified from a traditional fuel car as the research object.The finite element model of the vehicle’s 100% frontal collision was established,and the validity and accuracy of the model was verified.The simulation result shows that the transformation of vehicle front longitudinal frame was unsatisfactory.Which leads to unreasonable dash panel intrusion,deformation of the door frame and acceleration of the B-pillar.This may endanger the safety of passengers.In this paper,the maximum deformation of the battery pack in the extrusion direction and the maximum acceleration of the battery pack were used to evaluate the safety performance of the battery pack during the collision.It was found that the maximum deformation of the battery pack in the extrusion direction was small,within the safe deformation amount.However,the maximum acceleration of the battery pack was too large,which may affect the internal battery pack and raise safety problems.The finite element model of body-in-white was created,and its static and dynamic performance was analyzed.It was found that the bending stiffness,front torsional stiffness,rear torsional stiffness and the first-order modal frequency of the body-in-white structure were lower than similar models.So these performance needs to be improved.After the sensitivity of the key structural components of the body-in-white was calculated,the components that had a greater integrated contribution to each performance were found through entropy weight method and TOPSIS method.The objective functions were improving the static and dynamic performance of the body-in-white structure.At the same time,the impact on quality,vehicle collision performance and battery pack collision performance were considered.The thickness of the components was used as design variables,the multi-objective optimization of body-in-white structure was performed through design of experiment,construction of the approximate model and the second generation non-dominated sorting genetic algorithm.Then the final optimization plan was confirmed based on engineering practice.Comparing the results before and after optimization shows that the optimization effect was good.Aiming at the collision safety performance of the battery pack,topological optimization of the battery pack mounting bracket was performed using the SIMP method.And the optimal mounting bracket structure was determined,which reduces the acceleration of the battery pack during the collision.Then the collision performance of the frame longitudinal beam structure was optimized,using the approach of adding reinforcement plates at the bending places of the rear end of the front longitudinal beam and the middle of the longitudinal beam,adding an induction groove at the front end of the front longitudinal beam,and optimizing the internal reinforcement plates at the front end of the front longitudinal beam.Finally,the optimization plan was determined,which had obvious optimization effect.