Ductile failure behaviour characterisation of HRT with GISSMO and crashworthiness optimisation design of VRB-HRT

In this paper, a generalised incremental stress state dependent damage model (GISSMO) is used to accurately characterise the ductile failure behaviour of hot formed steel under collision, which is the excellent material selection to improve the crashworthiness and lightweight level of car body frames. The deformation patterns, structural failure patterns, and key crashworthiness indexes of B1500HS hot-rolled tube (HRT) are validated by the comparative researches between experiments and simulations. To fully exploit the lightweight potential of HRT, a variable-thickness rolled blanks hot rolled tube (VRB-HRT) is proposed to perform its crashworthiness optimisation design with considering the ductile failure by the extended hybrid cellular automaton for VRB thin-walled structures (eHCA-VRB) algorithm. It is found that the optimal case of VRB-HRT with considering the ductile failure is easier to meet the actual performance constraints, even though possesses a lower weight reduction ratio. Therefore, the ductile failure of VRB-HRT should be considered to guarantee the structural reliability by a more reasonable optimal design.