Quasi-static and low-velocity axial crushing of polyurethane foam-filled aluminium/CFRP composite tubes: An experimental study

Composite structures combine the advantages of multiple materials, which can improve the structural crashworthiness performance. This paper aims to combine the high strength of carbon fibre-reinforced plastic (CFRP), the excellent ductility of aluminium alloy (Al), and the good compressibility of polyurethane (PU) foam. Quasi-static compression and low-velocity impact tests were conducted on thin-walled tubes made of single materials and composite sandwich structures made of multi-materials, namely Al-PU-Al, Al-PU-CFRP, CFRP-PU-Al, and CFRP-PU-CFRP. The structural failure modes and crashworthiness indicators were analysed and compared under different loadings. The results showed that the CFRP thin-walled tube exhibited a progressive damage and failure mode, and the resultant force changed smoothly. The CFRP tube possessed a larger mean crushing force and specific energy absorption than the corresponding aluminium tube. Composite structures exhibited more stable deformation mode and higher energy absorption, compared with the sum of linear superposition (SLS) of individual components, due to the interaction effects among components. Among the designed four combinations, CFRP-PU-CFRP exhibited an ideal energy absorption under both quasi-static and dynamic impact, while CFRP-PU-Al produced the second highest specific energy absorption (SEA), with an increment of 42.0% compared with Al-PU-Al. With full consideration of crashworthiness performance and economic cost, CFRP-PU-Al can be recommended as an impact energy absorber for vehicles due to its lower economic cost than CFRP-PU-CFRP.