This study experimentally investigated the axial crushing characteristics of the hybrid tubes with the configuration of aluminum/carbon fiber-reinforced polymer (CFRP) (1/1) and aluminum/CFRP/aluminum (2/1). The effects of geometry size and fiber lay-up sequence on the axial crushing energy-absorption performances and failure modes of the two types of hybrid tubes were compared. The results showed that the energy absorption of the specimens with [0°/90°] lay-up sequence was better than that of the ones with [45°/−45°] lay-up sequence for both types of hybrid tubes. The proper length of the tubes should be selected to avoid too small a length-to-diameter ratio so that a stable and controllable progressive crushing failure mode can be achieved. When the crushing failure process was relatively stable, the specific energy absorption and crushing force efficiency of the 2/1 hybrid tubes were not affected by the geometric size. The energy absorption of the hybrid tubes was higher than the sum of the energy absorption of all the corresponding individual tubes, showing a positive hybrid effect.

In this study, the axial crushing behavior of aluminum/carbon fiber reinforced plastic (CFRP) hybrid tubes are systematically investigated numerically based on a three‐dimensional (3D) progressive damage model. Experiments concerning hybrid tubes with 1/1 and 2/1 lay‐up configurations are performed first to validate the numerical model. Then, the effects of chamfer at the end, stacking configuration, aluminum‐CFRP bonding state and thickness ratio of individual layers on the energy absorption characteristics of aluminum/CFRP tubes are further numerically analyzed. The simulation results suggest that the 3D progressive damage model can effectively simulate the crushing failure process and reveal the energy dissipation mechanism of aluminum/CFRP hybrid tube under crushing. It is observed that increasing the thickness of the CFRP layer does not promote the energy absorption, but the best energy absorption effect can be obtained by using a 1:1 ratio for the thicknesses of the inner and outer aluminum alloy layers in 2/1 hybrid tube. Finally, the economic performance of 2/1 hybrid tube, 1/1 hybrid tube, and aluminum alloy tube as energy‐absorbing structures is theoretically examined. The balance between mass and cost of the 2/1 hybrid tube is proven to be evidently better than that of the conventional 1/1 hybrid tube.

The aim of this study is to investigate the effects of metal-composite interface (MCI) adhesive quantity on the energy absorption and failure behavior of fiber metal laminates (FMLs) under ballistic impact. The dynamic shear and ballistic impact tests were systematically conducted, and CT scan was employed to quantitatively investigate the damage and failure mechanisms of the FMLs.The results reveal that the dynamic shear strength of MCI initially increases and then remains constant with the increase in the adhesive quantity at a constant strain rate. Moreover, the MCI adhesive quantity has a certain influence on the impact energy absorption of FMLs, and the degree of influence is related to the impact velocity. At an impact velocity of 360 m/s, the difference of energy absorption is maximal, approximately 14.7%. The distribution of total debonding area changes with increase in the adhesive quantity. When the impact velocity is 212 m/s, compared to FMLs with the lowest adhesive quantity, the total debonding area of FMLs with the highest adhesive quantity decreases by 774.57 mm 2 (9.20%), otherwise the debonding area near the rear aluminum alloy sheet increases by 595.94 mm 2 (58.99%). K E Y W O R D Sadhesive quantity, ballistic impact, failure mechanism, fiber metal laminates, metal-composite interface, split Hopkinson tie bar | INTRODUCTIONFiber metal laminates (FMLs) are hybrid composites containing metal alloys and fiber-reinforced composites (FRCs). [1,2] Combining the merits of both FRCs and metal alloys, FMLs not only exhibit high specific strength, specific stiffness, and excellent fatigue characteristics but also show outstanding load bearing capacity, impact resistance, and residual strength. [3][4][5] Therefore, FMLs are widely used in the aviation industry, such as wings, fuselage, and empennage of aircrafts, [6][7][8] and they also exhibit immense application potential in transportation, [9] armor protection, [10] and other fields.The mechanical properties of FMLs are primarily governed by the type of reinforcement fiber. [7] Currently, carbon fiber, glass fiber, and aramid fiber are mainly used as the reinforcement fibers in FMLs. [11] Ultrahigh molecular weight polyethylene (UHMWPE) fiber is a highperformance fiber with high modulus, low density, and outstanding energy absorption capacity. Therefore, it is extensively applied in the development of protective armors for soldiers and other military fields. [12][13][14] Over