Lightweight Design Of The Bumper Beam System Based On Multiple Modes

Recently,with the energy shortage and environmental pollution problems have become increasingly severe,lightweight body is gradually valued by the major automobile manufacturers.The system assembly by the front bumper beam and the crash box is located in deformation zone of the body,is the first vehicle collision parts in frontal contact,is one of the important parts of passive safety.Therefore,study on the bumper beam system in the event of a collision protection performance and its lightweight design are not only of great significance,but also meet the security,low-carbon,environmentally friendly vehicle development trend of three requirements.The paper takes the bumper beam system as an example to research the substructure performance and lightweight design.Considering the performance requirements under different modes are slightly different,the performance requirements setting method in multiple modes is proposed in this paper.Selection the evaluation index that can represent and reflect the characteristics of the bumper beam system's performance and comprehensive consideration the relationship of include and coordinate between the performance evaluation index in various modes,the design requirements of the performance of the the bumper beam system based on multiple modes are obtained.In order to avoid the shortcomings of the parts can only be verified in the vehicle performance and facilitate the performance verification and evaluation of lightweight schemes,the paper established an independent evaluation mode for the bumper beam system.The independent mode removed from the vehicle to achieve the performance decoupling.The impact information of the independent mode and vehicle mode were compared from four aspects of deformation mode,energy absorption,section force and intrusion,which verified the validity of the independent mode.With the performance requirement based on multiple mode as a constraint,with the independent mode as a carrier,the lightweight design of the bumper and the crash box are respectively carried out in this paper.The bumper include two kinds of materials of high strength steel and aluminum alloy.For the high strength steel bumper,under the condition of same section form,using alternative materials three kinds of high strength steel bumpers are compared.Considering the performance,quality,cost and other factors the MS1180 roll forming material is chosen as the best scheme.Under the condition that the space of the material are fixed,the performance of three kinds of high strength steel bumpers with different cross section are compared.It is found that the B type section has the best light weight effect.For the aluminum alloy bumper,the parameters of two kinds of aluminum alloy bumpers are optimized and the schemes of aluminum alloy bumper which meet the crashworthiness are obtained.For the crash box,the structure design is made by using the crushing theory of thin-walled beam and the CAE analysis method.On the basis of the crushing theory of the rectangular section thin-walled beam of hollow,the crushing theoretical formulas of the single hat,the double cap and the aluminum foam filled thin-walled beam are obtained.According to these theoretical formulas,the crash box schemes are designed to meet the performance requirements.With the aid of CAE technology,the influence of the section form,material,dip angle and thickness of four factors on the performance of crash box is discussed,and find that the cross section form has the greatest influence,the next is the thickness,material and dip angle.Based on this,the lightweight design of crash box is carried out.Finally,the lightweight scheme and the vehicle integrate in FRB and RCAR mode.By comparing the performance with the basic model,the lightweight scheme based on the independent evaluation mode is verified.