Research On Lightweight Design Of Electric Light Truck Drive Axle Housing

The drive axle housing,as a key part of the vehicle support,will be subjected to different forms of load from the carriage and the ground during driving.When bearing the normal service of the alternating load or excessive impact load,it is very easy to produce cracks or fracture in the dangerous parts,resulting in the failure of the drive axle housing,which greatly affects the safety of the car in driving.Therefore,at the beginning of the design of the drive axle housing should be theoretical calculation of its strength,stiffness and fatigue life;if the requirements are met then the lightweight design of the axle housing to improve the electric light truck range,comfort and reduce costs.At present,there are four main types of drive axles for electric light trucks in the market,which are motor-mounted rear drive axle,motor and reducer coaxial drive axle,motor and reducer parallel drive axle and wheelside motor drive axle.Based on this,this paper takes this drive axle housing as the research object and carries out lightweight design.First,a three-dimensional model of the electric drive axle housing of a model is established,and the external accessories that have less influence on the strength and stiffness of the axle housing are deleted in order to simplify the calculation.After that,the simplified 3D model is imported into FEM,and material parameters are set and meshing is performed to generate the FEM model of the electric drive axle housing.Based on this model,the FEM analysis was carried out for four ultimate working conditions,and the stress and deformation clouds for the corresponding working conditions were obtained,which satisfied the strength and stiffness requirements of the bridge casing.Secondly,the material used for the main body of the bridge shell is Q235 B,and the S-N curve of Q235 B is obtained by consulting the material manual.The S-N curve of Q235 B is corrected by the size coefficient,fatigue notch coefficient,surface finish coefficient and dispersion coefficient to estimate the fatigue limit value of the bridge shell under different life,and this data is imported into the finite element software to generate the S-N curve of the bridge shell.From the four limit conditions of the bridge casing cloud,we know that the bridge casing has the highest stress in the maximum impact condition,so the fatigue life analysis is based on this condition,and the minimum life of the bridge casing is calculated to be 5.79 million times.Finally,by analyzing the stress,deformation cloud and bridge shell fatigue life cloud,the dimensions of the bridge shell parts with maximum stress,maximum deformation and minimum life are taken as design variables,and the fatigue life and mass of the bridge shell,etc.are taken as responses for correlation analysis to find out the parameters with greater influence on the fatigue life and mass of the bridge shell as design variables;after that,with the mass and fatigue life of the bridge shell as optimization objectives,the maximum static stress,deformation and first-order modal frequency as constraints,combined with Latin hypercube test design method,kriging approximation model and multi-objective genetic optimization algorithm,the multidisciplinary objective-driven lightweight design of the bridge shell is carried out.The optimization results show that the performance indexes of the electric drive axle housing not only meet the requirements after optimization,but also have different degrees of improvement compared with those before optimization.Secondly,the mass of the electric drive axle housing before optimization was reduced from 75.8kg to 72.95 kg after optimization,with a weight reduction rate of 3.6%,achieving the goal of light weight of the electric drive axle housing.