Research On Lightweight Structure Of Electric Vehicle Battery Pack Based On Precision Casting Technology

Automobile lightweighting is a key technology for realizing energy saving and emission reduction of automobile products and increasing the cruising range of electric vehicles.It is also the direction of key research in the industry.As the load-bearing component of the electric vehicle battery pack,the battery pack is a key component to ensure the stability,safety and reliability of the power battery pack energy system.In this paper,the application of investment casting precision aluminum alloy technology in battery pack design is studied.The lightweight and optimized design of its structure is studied from three aspects: battery material,manufacturing process and simulation analysis.Firstly,referring to the layout form of the original model battery pack structure,according to the design principle of investment casting precision aluminum alloy castings,the battery pack structure is integrated.ZL201 A was selected as the casting material for the battery pack,and the casting system and process parameters of the battery package casting were designed using ProCAST.The simulation process of the casting process of the battery pack was carried out,and the visualization results of the casting and solidification process of the battery package casting were obtained,and the feasibility analysis of the casting process and the results was carried out.The results show that the shrinkage and shrinkage porosity of the battery pack castings is low,the casting system design meets the casting requirements,and the battery pack structure design is reasonable.Secondly,based on the battery pack physical structure model,the CAE simulation model is established.Based on the load conditions of the battery pack in the real vehicle,Hypermesh is used to analyze the static and dynamic performance of the battery pack structure.It can be seen from the analysis results that the static maximum stress is much smaller than the yield strength of the material,indicating that the excess strength needs to be further optimized.The modal simulation of the battery pack is compared with the test results,and the low-order modal frequency satisfies the requirement of avoiding the excitation frequency of the road surface.According to the national test standard of the power battery pack,the battery pack is subjected to simulation analysis and evaluation of random vibration and mechanical shock dynamic conditions,which provides a reference for further lightweight design.Then consider the dynamic effect of the battery pack structure,combining the S-N curve of the material and the Miner fatigue damage accumulation theory.Based on the power spectral density frequency domain method,the fatigue life of the battery pack was estimated using nCode software.The results show that the fatigue life of the battery pack meets the design requirements,and the fatigue life analysis provides a basis for the multi-objective optimization design of the battery pack structure.Finally,based on the static and dynamic performance analysis of the battery pack,OptiStruct is used to optimize the multi-objective size.Taking the thickness dimension of the battery pack structure as the multi-objective optimization design variable,the battery pack quality and the first-order modal frequency as the optimization targets,the static and dynamic performance as constraints,the response surface method is used to establish the approximate model,and the NSGA-II genetic algorithm is applied to the battery.The package structure performs multi-objective optimization.The optimization results show that the battery pack has a weight loss of 5.785 kg,which accounts for 15.05% of the total weight,and the weight reduction effect is obvious when the battery pack meets the static,dynamic performance and fatigue life requirements.The research content of this paper has important engineering practice value and guiding significance for the structural design of battery pack.