Research On Anti-fatigue Lightweight Of Pure Electric Light Truck Drive Axle

As the main urban logistics vehicle,the demand of pure electric light truck is increasing year by year.However,in the long-term driving process of electric light truck,the drive axle will be subject to a variety of iMPact loads.Over time,it will be damaged or even invalid,which will seriously endanger the driver’s personal safety.In addition,because the drive axle of electric light truck uses electric motor as power device,its structure scheme,transmission form and endurance capacity are very different from fuel vehicle.Therefore,this thesis mainly focuses on the static characteristic analysis and anti fatigue lightweight research of coaxial electric drive axle.The main contents are as follows:(1)The transmission structure analysis and dynamic parameter matching of pure electric light truck drive axle are carried out.Through the study of the mainstream electric drive axle transmission structure in the market,combined with the actual working conditions of pure electric light truck,the coaxial electric drive axle was selected as the power transmission structure of this electric light truck.At the same time,combined with the actual vehicle parameters of electric light truck and the required performance indexes,the parameters matching of its power system in line with the design requirements was carried out.(2)The finite element analysis of pure electric light truck drive axle was carried out.According to the characteristics of coaxial electric drive axle model,SolidWorks software was used to create the three-dimensional geometric model of the electric drive axle,and then the mesh was divided to generate the finite element model of the electric drive axle.Based on the four extreme working conditions of the electric drive axle,the ANSYS Workbench software was used to simulate the finite element model,and the displacement and stress distribution maps were obtained;The constrained modal analysis of the electric drive axle was carried out,and the natural frequencies of order 1-6 were obtained.CoMPared with the road excitation frequency,the results show that the drive axle will not be damaged by resonance;On the basis of modal analysis,the harmonic response of the left and right half shaft casings was analyzed.The results show that the maximum frequency range of displacement deformation is between the first and second natural frequencies,which is far greater than the normal external excitation frequency.(3)Fatigue life prediction of pure electric light truck drive axle was carried out.The static analysis results of coaxial electric drive axle were transmitted to nCode fatigue simulation software.The loading mode of fatigue stress was defined according to the automobile industry standard,and the corresponding S-N curve was selected according to the material of electric drive axle.Finally,the fatigue life of electric drive axle under bending condition was predicted according to the analysis process of nominal stress method,The fatigue life and fatigue damage distribution of the drive axle were obtained.The results show that the minimum fatigue life of the electric drive axle is 653000 times,which is greater than the requirement of 600000 times in the test standard.The most dangerous part is near the connection between the left half shaft sleeve and the left flange back transition sleeve.(4)The anti-fatigue and lightweight design of pure electric light truck drive axle was carried out.The thickness of the parts of the electric drive axle and the distance between the spring plate seat and the flange were taken as the optimization variables,and the minimum fatigue life and mass of the electric drive axle were taken as the objective functions.The approximate model between the optimization variables and the fatigue life and mass of the drive axle was established by using Latin hypercube design experiment method and Kriging method.Taking the mass less than 62.671kg and fatigue life greater than 6.53×105 as the restriction conditions,the mathematical model of the target response was established,and the optimal design scheme was obtained by calculating and solving.The results show that the weight of the optimized electric drive axle is 59.5kg,which is reduced by 5.06%,and the service life is 802900 times,which is increased by 22.9%.The purpose of reducing weight and increasing service life is realized.In this thesis,the nominal stress method and software co simulation method are used to calculate the minimum fatigue life of coaxial electric drive axle efficiently and accurately,and the maximum damage position is determined;through the construction of approximate model and multi-objective optimization algorithm,the optimal design scheme is solved.The optimization results show that the overall mass of the electric drive axle is reduced while the fatigue life is improved.