Experimental and numerical investigation on the crashworthiness performance of double hat-section Al-CFRP beam subjected to quasi-static bending test

Nowadays, hybrid structures, which combine low-density composites with low-cost thin-walled metals, have shown great effect in enhancing the performance of automotive body structures, especially the energy absorber components. This study focuses on the experimental and numerical investigation of the bending energy absorption behavior of CFRP/aluminum hybrid double hat-section beams used in the side part of the car body. In the experimental section, two types of double hat-section beams were fabricated: aluminum and Al/CFRP. These beams were then subjected to quasi-static three-point bending tests. The results demonstrated that the hybrid beam exhibited superior energy absorption capabilities compared to the single beam. Subsequently, a finite element model was developed using LS-Dyna software and was validated by comparing the experimental and numerical load-displacement results. In-depth numerical analyses were conducted to investigate the influence of various design parameters, including CFRP-reinforcement configuration, numbers of CFRP layers, CFRP ply-angle, CFRP reinforced length, and aluminum/CFRP mass, on crashworthiness indicators. The numerical findings indicate that the hybrid beam with [0](4,)[45/-45](s) ply-angles exhibited better crash force efficiency (CFE) and specific energy absorption (SEA) compared to other ply-angles, respectively. Furthermore, increasing the number of CFRP layers within the total beam's mass improved its energy absorption capacity. It was also revealed that the CFRP length on the upper and lower hats could be considered as 42.5% of the total aluminum beam length, as opposed to the full CFRP length, providing enhanced energy absorption capabilities.Highlights Bending behavior of the Al and Al/CFRP double hat section beams. Effects of variable thickness and identical mass on the double hat section beam. Effects of variable ply angle and number of CFRP layers on the hybrid beams. Discrete effect of CFRP reinforcement configurations and inner CFRP lengths.