Lightweight Optimization Of B Pillar Based On The Side Impact And The New Type Blanks

Accompanying rapid increment of retaining automobile, the energy tense, environment pressure and vehicle safety become increasingly serious, which will prevent the sustainable development of automotive industry. Previous studies have shown that lightweight is an effective approach to cover above problem. B pillar, as an important assembly of passenger car side configuration, is the main component to absorb energy in side impact. Its intrusion, intrusion velocity and deformation mode are the main causation of the injuries of occupants, so, the side crashworthiness of B pillar is the precondition of lightweight.A side impact finite element model of full car and a simplified side impact element model of B pillar were developed at first. Then the thickness of the B pillar outer, B pillar inner, B pillar reinforcement and B pillar seatbelt fixing support was optimized by using orthogonal experimental design, approximate model and sequential quadratic programming. The desired thickness of every panel was obtained and the mass of the B pillar was reduced by7.8%. And finally, the B pillar outer was divided into four regions in height-direction and three kinds of improved plates were used for B pillar outer. Firstly, varying yield strength plate was implemented. The yield strength of each region and the location of the transition region were optimized, and the mass of the B pillar was reduced by11.28%. Secondly, tailor rolled blank was used. The thickness of every region and the location of the transition region were chosen as the design variables which would be optimized, as a result, the mass of the B pillar was reduced by20.05%. Finally, a new kind of plate with different thickness section and varying yield strength was used to replace the original B pillar outer. The thickness and yield strength of each region and the location of the transition region were the variables, and the mass of the B-pillar was reduced by22.82%after optimized.The results indicate that:thickness optimization and three kinds of new plates can reduce the mass of B pillar and simplify the manufacturing process. The third kind of plate with both advantages of tailor rolled blank and varying yield strength plate is the most effective method to optimize the B pillar, and tailor rolled blank is more effective than varying yield strength plate. Larger thickness and greater yield strength in central section of the B pillar can largely enhance the side crashworthiness.