Optimization Design Of The Structure Of B-pillar Based On Roof Crush And Side Impact Analysis

B-pillar, which resists large deformations of roof and side structure in roof crushand side impact, improves the roof strength and the crashworthiness of side impact.The optimization design of the structure of B-pillar has important significance.Taking a passenger car for example, the numerical analysis models of the roofcrush and the side impact were built. The accuracy of the models was verified by testresults of the roof crush and the side impact. The results show that the stiffnessdistribution of B-pillar is unreasonable. The roof strength is in the low level. Theintrusion and its velocity at B-pillar are too large in side impact. Meanwhile, threetypical kinds of B-pillar deformation modes were analyzed in side impact. A roofstructural crashworthiness design strategy which aimed at the application of highstrength steel was proposed.The optimization design of B-pillar was carried out by considering the roofstrength and the safety of side impact. The inner plate of B-pillar, as well as the outerplate, consists of two different parts which were welded together by tailor-weldedblank technology and formed by high strength steel. The type of material and thethickness of steel were treated as discrete design variables. The optimization modelwas established by considering the material cost, the impact force, the intrusion andits velocity at B-pillar. The moving least square response surface and geneticalgorithm were utilized to improve the crashworthiness of B-pillar.The results indicate that the weight of B-pillar is effectively reduced by13.8%by using the high strenght steel and Tailor-welded blank (TWB). Meanwhile, thematerial cost remains unchanged. The intrusion and its velocity at B-pillar arereduced by3.8%and5.6%respectively. The reasonable deformation mode of B-pillaris obtained in side impact. The Abbreviated Injury Scale (AIS) is reduced to2.967.The roof strength is enhanced by18.53%. Thus, the lightweight design of B-pillar isrealized and the roof strength and the safety of side impact are effectively improved.