Crashworthiness Study And Structure Optimization For S-shaped Front Rails Of Automobiles

The front rail is a major structure for absorbing energy during a car crash.This paper aims to improve crashworthiness of S-shaped front rails.Unlike other researches,the Sshaped front rails in this research are divided into three segments and the crashworthiness of each segment is studied individually.By comparing the degree of deformation with evaluating indicators of crashworthiness,it is found that the middle segment of front rail has the largest effect on the crashworthiness of S-shaped front rail.On basis of the above result,the tailor-welded blank(TWB)is applied to S-shaped front rail.There are some reasons why TWB is made by welding three blanks together.Each blank can have different thickness and can be made by different materials,which makes the structure of S-shaped rail more flexible.Thus,the crashworthiness can be improved in this way.Besides,S-shaped front rails with circle cross-section are proved to have a better crashworthiness as compared with S-shaped front rails with different cross-sections.The TWB type S-shaped front rails,whose blank 1,blank 2 and blank 3 are respectively made by DP450、DP780 and DP590 high strength steel,also present a better crashworthiness as compared with TWB type S-shaped front rails made by different material groups.Moreover,to seek the best thickness solutions of three blanks of TWB type S-shaped front rails,a multi-objective optimization is employed in the present paper.The specific energy absorption(SEA)and peak force(PF)are set to be two objective functions,and the thicknesses of three blanks(T1,T2 and T3)are set to be design variables.As a result,the optimization shows that the effective thicknesses of T1、T2 and T3 are 1.50 mm,2.92 mm and 2.15 mm,respectively.