Research On The Lightweight Of Composite Battery Box Based On The Safety Of Electric Vehicles

With the popularization of electric vehicles,the safety and stability of batteries are gradually being valued by people.As the carrier and protection of the battery system,the structural strength of the battery box directly determines the safety performance of the electric vehicle.The quality of the battery box is closely related to the range of vehicles,and lightweight is also an important factor that needs to be considered when designing the battery box.As a high-performance material,carbon fiber composite material has great advantages in improving structural strength and achieving lightweight goals.At the same time,carbon fiber composite materials are also designable,and the performance of the structure can be effectively improved by designing the layering method.Based on a variety of common accident conditions,this paper analyzes the performance of the battery box.According to the analysis results,combined with composite materials,the weight of the battery box is reduced on the basis of ensuring safety.The main research contents of this paper are as follows:(1)Combining the perforated plate compression and low-velocity impact tests,the composite material damage criterion is evaluated.The evaluation results show that the Hashin damage criterion has good accuracy under the above conditions.The damage criterion is selected for compounding in the subsequent simulations.Material simulation.(2)Based on the design requirements of the battery box,design the structure model of the original battery box.The model is composed of four parts: the upper box cover,the lower box body,the connecting structure and the supporting structure.Using the UG software to establish a 3-D model of the battery box and a finite element model of the battery box.(3)Based on GB 38031-2020 and GB/T 31467.3-2015,combined with common causes of electric vehicle accidents,design six battery box safety analysis conditions,specifically: static strength analysis,modal analysis,random vibration analysis,Multiaxis vibration damage analysis,extrusion condition analysis and bottom impact condition analysis.The analysis results show that the first-order modal frequency of the battery box is relatively small,lower than the external excitation frequency,and is prone to resonance,which affects the safety of the structure;the maximum stress of the battery module under the bottom impact condition exceeds its safe working stress range;There is room for weight reduction in the whole box.(4)Based on the results of finite element analysis,the structure optimization of the battery box was carried out,specifically: optimization of the unfolded shape and size of the upper cover of the battery box,so that the first-order modal frequency was increased above the external excitation frequency,and the resonance frequency was avoided,Reduce the quality of the upper box cover by 23.8%;optimize the size of the battery box lifting lugs,increase the material usage rate,and reduce the weight by14.0%;use T700 carbon fiber/2510 epoxy resin-based woven composite material to replace DC01,based on extrusion conditions As well as the bottom impact conditions,multi-objective optimization of the lower box is carried out,and the thickness of the layer is designed to achieve a weight reduction of 65.8%.(5)According to the optimization results,the battery box is re-modeled and simulated under multiple conditions.The simulation results show that the optimized battery box meets the safety requirements and achieves an overall weight reduction of10.5%.