Crashworthiness design for bi-graded composite circular structures

An innovative double functionally graded composite circular beam comprised of axial and radial graded foam filler is proposed to improve the safety of vehicle under lateral load. The numerical model is established and validated by three-point bending experimental testing. To explore the benefits of the novel functionally graded foam (FGF) material, graded foam filled circular beams with axial and radial graded directions are compared with homogenous foam filled counterparts. FGF filled beams are credited with primarily outward fold which leads to expanded crushing zone. Then, parametric studies are carried out to investigate the effect on thickness and yield stress of column wall of functionally graded circular beams. Furthermore, the bending behaviors of effective FGF filled circular beams are also investigated to improve the weight efficiency. Lastly, multiobjective optimizations of FGF filled beams, effective FGF filled beams and uniform foam filled beams are conducted to enhance crashworthiness. The optimization results show that FGF filled beams exhibit superior Pareto solutions to the uniform foam-filled beams. Especially, effective FGF filled configuration can significantly improve weight efficiency without compromising bearing capacity. The findings of this research offer a new route of designing novel lightweight bumper absorbers with improved crash characteristics. (C) 2018 Elsevier Ltd. All rights reserved.