Lightweight Design And Performance Optimization Of Integrated Battery Box

China’s automobile industry has devel oped rapidly in recent years,and China’s automobile production and sales have ranked first in the world for many years.However,with the rapid growth of fuel vehicles,the environmental,energy,and noise issues have also caused serious negative impacts on society and the economy..With the successive introduction of emission policies,new energy vehicles have developing rapidly.The electric vehicles is the most popular new energy vehicles appearing on the Chinese market.The rationality of the battery box design is not only related to the battery life and performance,but also related to the life safety of the occupants.Therefore,the crashworthiness and weight reduction of electric vehicle structures is an important research topic.Based on the strategic emerging technology projects in Hunan Province[2016GK4008],this thesis will design and optimize the integrated battery box of a certain electric vehicle,use finite element software to analyze its static and dynamic characteristics and drop process,and optimize and improve the battery box.The weak and unreasonable structural parts in the original design model,and the crash safety of the optimized battery box is verified by the side collision of the whole vehicle.The main research work of the thesis is as follows:1)According to the digital model of the battery box,rationally simplify the process and use Hyper Mesh software to establish the CAE model.According to GB7258 and other relevant standards,the boundary conditions and loads of static working conditions are determined,and all degrees of freedom of the corresponding connection parts are constrained to perform two kinds of static working conditions analysis of bumpy brakes and bumpy turns.The allowable stress of the material is obviously low,there is a lot of redundant quality,and the design is too conservative.Through dynamic performance analysis,it is found that the first-order mode of the upper cover of the battery box is low,and it is located in the road vibration excitation zone,and resonance is likely to occur when driving.According to the provisions of GB / T 31467.3-2015,a drop simulation experiment was carried out on the battery box,and it was found that the upper cover of the battery box had greater stress and strain during the drop process,and the rigidity was insufficient.Some welding points of the lower box cracked,and it needs to be improved.2)In view of the shortcomings of the initial design of the battery box,Optistruct is used to optimize and improve the compon ents of the battery box: use topology optimization to reduce the weight of the battery protective cover and the reinforcing beam,and use size optimization to allocate the battery protective cover,tray,and lower cover The material thickness of other comp onents reduces the quality and improves the performance of the system;using morphological optimization to improve the modal frequency and drop stiffness of the upper cover of the battery box,and finally makes the battery box achieve the 10.2% lightweight goal,while The first-order mode is increased by 97.9%,the maximum drop stress is decreased by10.7%,the maximum strain is decreased by 32.2%,and the maximum stress and strain are still within a reasonable range under static conditions.3)Establish the side collision model of the electric vehicle.According to GB20071-2006,the boundary conditions and constraints of the 50km/h movable barrier for the collision of the whole vehicle are defined,and the collision simulation test is carried out.The experimental results,this integrated battery box meets the relevant protection requirements and has good crash resistance.It also shows the rationality of the design scheme of the integrated battery box based on high crash resistance.