Study On Lightweight Of Bus Body Frame Based On Sensitivity Analysis

In recent years,as the Sustained growth of car ownership,domestic city are not only confronted with huge traffic pressure,as well as caused prominent energy and environmental problems increasingly.hence in the era of seeking Low-carbon green economy,automobile lightweight technology has turn into one of the significant methods to realize energy conservation and pollution reduction.This paper takes a pure electric bus as the research object and studies the lightweight technology of bus body frame.Firstly,according to the actual size of the bus,the three dimensional skeleton model of the bus is established by CATIA software.and the FEA model of the body skeleton was get by fore-processing the model with Hyper Mesh software.the strength and stiffness of the bus skeleton model are analyzed under four typical working conditions,on the basis of the national standard and Enterprise production experience,the original bus skeleton model meet the design requirements,and there is a certain optimization space.meanwhile,to Validate the ride of the bus,a modal analysis of the bus skeleton is performed.by comparing the modal frequencies of each order with the external excitation frequency,it shows that there is no modal coupling between the modal frequencies of each major component of the bus and there is no modal coupling between the bus frequency and the external excitation frequency,and there is no resonance due to the external excitation,which has good ride comfort.Secondly,based on static and modal analysis,the body skeleton was size optimized.in order to precisely determine the design regions and design variables of the design for size optimization,the analysis method of sensitivity was used to find the effect of the change of rectangular tube thickness on the skeleton strength and body mass by changing the wall thickness of rectangular tubes in different parts of the body skeleton,and 75 Components were identified through sensitivity calculation,with the thickness of rectangular tubes as the design variable,the body skeleton strength,stiffness and modal frequency as the constraints,and the mass minimum is the objective function for size optimization,and the optimized body skeleton structure is obtained according to the variable size after size optimized,and the mass is reduced by 3.54%.Finally,in the light of the results of the optimized body skeleton static force analysis with less stress on the front surround skeleton,and the front surround material is considered to be further lightened by replacing the original front surround material with low density and low strength material on the basis of dimensional optimization.The front skeleton material was replaced by from Q345 to aluminum alloy 6061-T6,and the results show that the maximum stress value,maximum deformation value and low-order modal frequency meet the requirements,and the body skeleton reduces the mass of the body skeleton by 1.34%compared with that after size optimization.Based on FEM,both the size optimization design and the application of local lightweight material replacement of the bus body skeleton through sensitivity analysis,resulted in the reduction of the total mass of the bus body skeleton by 86.00 kg,This light weighting method of bus body skeleton has certain applicability.