Research On Lightweight And Solder Joint Optimization Design Of An Electric Vehicle Battery Case

As one of the key components of electric vehicle,the safety of power battery has become a hot issue.Since the battery case is the first barrier of the power battery,the reliability of structural design is closely linked with the safety of the power battery.This paper studies the structural optimum design of battery case to overcome the default of large mass and its poor stiffness performance under complicated working conditions.From the results of static analysis,as bumps are encountered,the displacement of battery pack structural rigidity is prone to become too large as the phenomenon of insufficient rigidity.The results of modal analysis shows that the first-order natural frequency of battery case is only 22 Hz,resonance phenomenon may occur.In addition,since the maximum first-order amplitude occurs at the bottom of the battery case,it is necessary to optimize bottom structural design of battery case.On the other hand,light-weight design is applied to the side surface of battery case due to its stronger rigidity.In order to improve the defect of insufficient rigidity of bottom surface of the battery case,this paper uses optistruct software to optimize the layout of stiffeners to enhance the local rigidity of battery case.The optimal topology design of sides of case is performed to achieve the light-weight goal.The results shows the optimized first-order natural frequency rises to 28.6 Hz,the maximum displacement on the bumpy road is 3.68 mm,which can meet requirements of the relevant state standard.It has remarkable effect in declining the weight of stamping parts of battery case by 16%.Since the energy consumption of aluminum welding is much larger than iron and other metals,this paper rearranges layouts of welding spot between case and upper beam.Based on the variable density method,the volume of welding spot is taken as the optimization variables,minimizing weighted strain energy under different working is taken as design objectives,declining the volume of case is taken as optimization constraint.Lastly,this article uses random vibration method to verify the rationality of optimization results.