Research On Lightweight And Impact-resistant Structure Of Electric Vehicle Battery Box

Power battery is the only energy source of pure electric vehicles,which is related to the dynamic performance of the car,and its impact resistance structure is related to the safety of passengers.The battery box,as the carrier of the power battery,can ensure the safety of the battery,and its impact-resistant structure can also protect the safety of passengers.The battery box is a relatively large-scale automobile component,and its energy consumption is relatively large.Therefore,it is particularly important to research the battery box in terms of light weight and impact resistance structure.Because the fiber composite material is light in weight,has a large specific modulus,and has a specific stiffness and a specific strength that are superior to those of metal materials,the use of composite materials instead of metal materials for structural design of battery boxes is of great significance.This article first analyzes the bearing characteristics of the battery box,applies the basic theory of composite material mechanics,and the methods and principles of composite structure design,and uses composite laminates to design and analyze its load beam and box structure.The mechanical performance parameters,strength and stiffness of various fibers and resins are compared,and a cost-effective HT3 / 5222 carbon fiber resin-based composite material is selected for research and design of electric vehicle battery boxes.Taking a metal battery box of a certain company as a prototype,the structural design index of the composite battery box was determined by analyzing its structural stiffness.Secondly,the basic equations of elastic mechanics and the classic laminated plate theory of composite material mechanics are used to combine the boundary conditions to simplify the structure of the battery box into simply supported beams and long laths for mechanical analysis.The deflection equation and the first-order natural frequency equation of the bearing structure of the battery box are established.Taking the deflection of the strengthening beam as the optimization target,the lay angle and the number of lays as the optimization variables,and considering the comprehensive cost,the method of combining numbers and shapes is used to determine the layup plan of the strengthening beam.Third,optimize the topography of the upper box cover,and establish five reinforcing ribs of equal size and shape according to the characteristics of the force.Establish a mathematical optimization model with the first-order natural frequency of the reinforcing ribs as the optimization target;The mathematical model of the cabinet is established with the deflection as the optimization target and the first-order natural frequency as the constraint.Set the ply angle and the total number of plies as design variables,and use genetic algorithms to solve the optimal variables of the upper box cover and lower box respectively.Finally,a finite element model of the composite battery box is established.The static and dynamic analysis of the battery box is performed under different load conditions,and the analysis results of the designed composite battery box and metal battery box are compared.From the perspective of statics,the deformation of the composite battery box is less than 0.5mm,and the failure factor does not exceed 1,which meets the static strength performance requirements of the battery box.From the perspective of dynamics,one of the composite battery boxes is calculated through modal analysis.The first-order natural frequency is 44 Hz,which meets the vibration requirements of the battery box,and the vibration amplitude of the composite battery box is smaller than that of the metal battery box,indicating that the dynamic stiffness performance is good;The maximum deformation of the composite battery box under three loading conditions of frontal collision,side collision and rear collision did not exceed the dynamic performance index,and the maximum acceleration was 2.08 g to meet the collision performance requirements.This research aims at the lightweight and impact-resistant structural design of battery boxes for electric vehicles,and discusses the methods of structural design and optimization using composite materials.The results show that the rigidity and strength of the composite battery box meet the design requirements and are better than metal battery boxes.The weight is reduced by 67.98%,which meets the lightweight design requirements.This provides a reference for the application of composite materials in automobiles.