Gradient origami double-layer multi-cell tubes: Design, synergistic energy absorption mechanism, and crashworthiness optimization

To address the core contradiction that both low peak collision force (PCF) and high specific energy absorption (SEA) are difficult to balance simultaneously in energy-absorbing structures, and to achieve their synergistic optimization, this study proposes a novel pre-folded double-layer multi-cell tube (PDMT) configuration inspired by origami structures. The incorporation of origami-inspired geometric patterns effectively suppresses initial peak loads, while leveraging the inherent SEA advantages of multi-cell structures. Through a bilayered nested design, this architecture achieves simultaneous optimization of low initial impact force and high energy absorption efficiency. By introducing the in-plane thickness distribution gradient k[jls-end-space/], the energy absorption capacity of the gradient double-layer multi-cell tube (GDMT) is significantly enhanced compared to that of the PDMT, with the SEA showing a maximum increase of 65.9%. For quantifying the constraining influence of ribs on double-layered tube structures and their enhancement on crashworthiness, the contribution of individual components and the interaction between them to the energy absorption of the GDMT was investigated. It is found that the interaction exerts the most significant influence on the energy absorption of the GDMT. Meanwhile, a multi-objective optimization method was employed to optimize the GDMT, yielding the optimal solution. Its PCF and SEA were 117.8 kN and 26.8 kJ/kg, respectively. The research findings establish a critical theoretical foundation for the crashworthiness structural design of next-generation high-speed trains, provide actionable technical guidance, and offer a new paradigm for the optimal design of origami-inspired multi-cell structures.