Sustainable composites with ultrahigh energy absorption from beverage cans and polyurethane foam

The worldwide annual consumption of metal beverage cans is enormous. Reusing these discarded empty beverage cans (EBCs) as an energy absorber for kinetic energy absorption would be highly beneficial for promoting energy savings, reducing greenhouse gas emissions, and establishing a circular economy. However, EBCs are susceptible to deformation in an undesirable failure mode under axial crushing loads, which is unfavorable for energy absorption. This study demonstrates the effectiveness of combining empty cans with polyurethane (PU) foam to enhance the energy absorption performance of EBCs. The study develops low-cost and sustainable composite structures (SCSs) from waste beverage cans. Surprisingly, the specific energy absorption (energy absorption per unit mass) of the SCSs is 2.44 times that of the EBCs under axial quasi-static compression. The average axial crushing force of SCSs is approximately 23.4 times the weight of the empty can itself. Furthermore, the SCSs exhibit excellent crashworthiness performance in various dynamic impact scenarios and superior energy absorption characteristics compared to other typical tubular composites and metamaterials. This study demonstrates an extremely feasible approach for developing next-generation eco-friendly and high-performance energy-absorbing composite materials.