Structure Analysis And Lightweight Research Of A SUV Body-in-white

Body-in-white as one of the important assemblies of automobile,its weight accounts for about 30% to 40% of the vehicle.About 70% fuel consumption in no-load driving is for the body weight.Therefore,lightweight of body-in-white plays a considerable contribution,and it must ensure the body to meet the performance requirements.The reasonable optimization design method is to improve the utilization ratio of material and achieve the purpose of lightweight body.In this paper,combining with lightweight optimization theory and enterprise engineering practice,a domestic SUV body-in-white was used as the research object.Considering the static and dynamic stiffness of the body structure,strength of multiple working conditions and local structure and so on,the multi-objective lightweight study of the body was carried out with the components thickness as the variables.The main jobs were as follows:(1)Finite element modeling of BIW.Based on the white body three-dimensional data.First of all,the whole body was divided into multiple sub-assemblies,then each subassembly was modeled in detailed introduction to the modeling specification of each subassembly.And then each sub-assembly was assembled to build the finite element model of BIW.Finally,Summed up a set of the process of system modeling process was summrized.(2)Finite element analysis of body structure performance.According to the OEM requirements of the vehicle performance and test.The BIW was analysed for bending stiffness,torsional stiffness,low frequency intrinsic mode and multi-mode strength crown resistance,and local area while strength insufficient were optimized.(3)Sensitivity analysis of the body.Combining with the feasibility of manufacturing,92 parts which have the potential to reduce the weight of BIW were selected.Sensitivity analysis of mass,mode and stiffness to select the thickness of the larger impact on the performance of parts to optimize the body structure performance.And then the concept of relative sensitivity was introduced.The relative sensitivity of mode to mass and stiffness to mass were calculated.Selecting smaller impact on the performance and larger contribution on the lightweight of the body parts for lightweight optimization.(4)Research on multi-objective lightweight of vehicle body.The thickness of the selected parts which 12 for enhancing the bending stiffness of the body and 33 for body lightweight were calculated as the design variable by sensitivity.The torsional stiffness of the body,the first torsion mode and the first bending mode were the constraint conditions.The lightest weight and the maximum bending stiffness of the BIW were design goals for multi-objective lightweight analysis.An improved non-dominate sorting genetic algorithm was used to optimize the vehicle body directly.Selecting the optimal solution of the nondominate solution based on the minimum quality as the focus.The feasibility of lightweight scheme was verified by mode,stiffness and strength performance of the body.Final reduced the weight of the vehicle 9.27 kg.