Structural Safety Analysis And Optimization Of An Electric Car Battery Pack

The electrification and lightweight of vehicles are the powerful measures to deal with the energy crisis and environmental pressure.Nowadays,electric cars are becoming more and more popular,and battery pack’s energy density also increases with the social demand,the ensuing safety problems of the pack have aroused widespread concern in the society.In order to ensure the safety and practicability of electric vehicles and accelerate the popularization of electric vehicles,it is necessary to study the safety of battery packs.Therefore,combined with the research methods of experiment and simulation,this project analyzes and optimizes the structural safety of a battery pack.The structural safety and lightweight characteristics of battery pack are improved.Firstly,local compression experiments are carried out on cell,module and battery pack of a power battery system respectively.Experimental result shows that the deformation threshold of the 18650 ternary lithium battery under the compression load is 5mm,which will be used as the safety criteria of the bottom collision of the battery pack.Moreover,the mechanical response and specific failure behaviors of the cell,module and battery pack under compression overload are obtained through experiments,which provided a basis for the establishment and verification of the finite element model below.Then,taking the experimental data as input and reference,the homogenization models of cell,module and pack are established and verified respectively,which balances the calculation accuracy and the calculation efficiency of the finite element model of large battery pack.Based on the equivalent model,the bottom collision and vertical impact simulations of the battery pack are carried out,and the stru ctural safety of the battery pack is analyzed from the perspectives of stiffness and strength.The results show that the battery enclosure is enough to protect the internal structure in the bottom collision.But under the impact load,the stress levels of enclosure structures vary greatly,the strength needs to be optimized.Finally,in the light of the simulation results,the structures that need to be optimized are determined.The thickness of the selected structures are taken as the size variables,and four kinds of dual-phase steels with different strength are taken as material variables.According to the process of “establishment of mathematical model-design of experiment-establishment of approximate model-optimization”,the material-structure matching optimization of battery enclosure is carried out.The optimized structure-material matching design improvess the structural safety of battery pack,and balances the stress distribution of each structure of the battery enclosure.At the same time,the mass of the battery pack is reduced by 8.062 kg,about 2.1% of the total mass.The results validate the effectiveness of structure-material matching optimization scheme in enhancing the performance of battery pack structures to some extent.