Crashworthiness design of gradient bionic Al/CFRP hybrid tubes under multiple loading conditions

A "rigid and flexible" fiber-wrapped metal bionic hybrid structure (BH) is proposed, in which the fiber-reinforced composite is wrapped to make up for the "rigidity" of the material, and the gradient design plays the "flexibility" of the structure. Firstly, the CFRP enhanced stiffness is used as an induced mechanism to achieve variable stiffness design, which can avoid the complex processing problems faced by conventional design and effectively reduce the mass of the structure. Secondly, the crashworthiness of the Bionic Hybrid Thin-walled (BH) tube under axial and oblique loading angles was systematically investigated by changing the thickness parameter of the inner core Al to the outer CFRP winding angle using the validated finite element model. Finally, the prediction accuracy of three proxy models (RSM, KRG, SVR) is compared, and two optimization algorithms (NSGA-II and MOPSO) are combined to achieve the optimal crashworthiness under multi-angle loading conditions. The optimized BH tube has obvious advantages, most notably, the SEA is improved by 47.46%, 42.72% and 53.73% under axial collapse load compared with pure Al tube, pure CFRP tube and original BH tube, respectively. The results reported in this article provide valuable guidance on the design of new variable stiffness tubes.