Bending collapse and energy absorption characteristics of aluminum/CFRP hybrid square hollow section beam for lightweight structure development

Abstract

The bending collapse and energy absorption characteristics of an aluminum (Al)/CFRP hybrid square hollow section (SHS) beam were studied to improve structural rigidity and energy absorption characteristics of an Al SHS beam without compromising lightweight performance. Current methods of increasing the cross section thickness of an Al SHS beam for high structural rigidity and energy absorption capability are highly restricted by structural integrity problems, and this was proved by the observation of two different collapse behavior modes depending on the geometric characteristics. The stable bending collapse mode with plastic hinge formation can guarantee high structural integrity. In the case of the abrupt bending collapse mode with tensile tearing failure, in contrast, it is difficult to predict the failure. However, in the Al/CFRP hybrid SHS beam, the structural rigidity of Al SHS beam can be highly improved in the early stage of linear elastic and plastic buckling behavior regions by CFRP reinforcement and the energy absorption capability is also thereby highly improved. The CFRP is fractured in a catastrophic failure mode by unstable interlaminar and interlayer crack propagation under an unanticipated loading direction, but the catastrophic failure of CFRP can be changed to a progressive failure mode when the fracture of CFRP is guided by plastic deformation of Al. Therefore, in the hybrid SHS beam, stable bending collapse behavior with plastic hinge formation can be guaranteed by gradual degradation of the material properties of CFRP caused by progressive damage behavior and high structural integrity can be ensured. At the same time, in the bending collapse region, the peak load is decreased slowly by proper suppression of plastic hinge formation through CFRP reinforcement and the energy absorption capability is thus highly increased. Energy absorption characteristics and bending collapse behavior of an Al/CFRP hybrid SHS beam fabricated by a co-curing ...