Abstract:

The relationship between the crushing force and material strength and thickness of thin?walled beam under three?point bending condition is studied， and a lightweight design method for B?pillar is proposed. For the lower end of B?pillar， it crushes and bends in side crash， which can be approximately equivalent to three?point bending condition， the high?strength steel with high?ductility is used instead of the ordinary high?strength steel with lower strength， and its lightweight design is carried out. For the upper end of the B?pillar， the rigid rotation occurs in side crash， which can be equivalent to the statics problem. The equivalent static force of side crash is applied， the upper end of the B?pillar is divided into N segments， and the thickness of each segment is optimized by using Optstruct software. Finally， an optimization is conducted on a real vehicle by introducing the optimization schemes for upper and lower ends of B?pillar into the side crash model of the vehicle. The results show that after optimization， the intrusion speed and intrusion amount of the main parts of B?pillar are almost equal to those of the original design， demonstrating the effectiveness of the lightweight design. The optimization achieves a lightweighting effect of 24% （1.9 kg）， with its crashworthiness unaffected.

Key words: B?pillar, side crash, lightweight design, three?point bending, dimensional optimization