| Based on the current rapid growth of new energy vehicles represented by electric vehicles,the power battery box as the main bearing device of the battery system is of great significance to electric vehicles.This paper proposes a lightweight solution for a power battery box through static and modal analysis,safety simulation analysis,structural optimization design and fatigue life analysis for a power battery box of an electric vehicle.The main research work is as follows:(1)The three-dimensional model of the power battery box is established through CATIA,the structure is simplified according to the analysis requirements,and the finite element model is created.Based on the basic idea of finite element method,static analysis is carried out under four typical working conditions of left turn on bumpy road,right turn on bumpy road,forward braking on bumpy road,and reverse braking on bumpy road.The analysis result shows that the strength and safety of power battery box good.It means that the design of the top cover and the bottom of the lower box has more surplus.Carry out modal analysis,extract the first six modes and find that the natural frequency of the first-order mode of the power battery box is lower at 28.54 Hz.In the excitation frequency range of electric vehicles,there is a risk of resonance occurring around the side of the lower box.The rigidity of the side wall of the cabinet is insufficient.Provide a reference for the following to choose different optimization methods for each component of the power battery box.(2)Carry out safety simulation analysis of the power battery box in combination with relevant national standards,and perform random vibration simulation analysis in X,Y,and Z directions and extrusion simulation analysis in X and Y directions,respectively.It can be known from the simulation that the power battery box meets the safety requirements of the national standard.Provide a basis for the following optimization design of power battery box.(3)According to the results of static and modal finite element analysis,different optimization schemes are used for each component of the power battery box.Multi-objective and multi-case topology optimization design was carried out on the top cover and the bottom of the lower box,and the topography of the lower box side wall was optimized.After the optimization,the weight of the cabinet changed from 26.37 kg to20.66 kg,and the quality decreased by 21.65%.At the same time,the results of the improved new power battery box were checked,which proved the rationality of the lightweight design.(4)Using nCode DesignLife software,based on fatigue cumulative damage theory and material fatigue characteristics.After calculation and improvement,the random vibration fatigue life of the new power battery box is higher than the safety standard of7.56 × 104 s,indicating the feasibility of improving the design.In summary,the improved design of a new power battery box meets various performance requirements,while achieving a lightweight design,which has certain practical application value. |
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