Crashworthiness of Kirigami-inspired hourglass structures under quasi-static and impact loading

This study introduces a kirigami-inspired hourglass structure (KHS) as a novel thin-walled energy absorber for aerospace crashworthiness applications, including lightweight protective components and advanced sandwich core systems. The KHS is engineered to achieve high energy absorption efficiency and improved impact resistance through a geometrically induced deformation mechanism. Its performance was evaluated through experiments and numerical simulations and was compared with three reference structures, namely a square tube, a kirigami inspired truncated pyramid (KTP), and a folded kirigami (FK) structure, all having identical wall thicknesses. Quasi static compression tests and validated finite element analyses showed that a single KHS unit achieved a specific energy absorption of 11.97 J/g, which is 2.8, 1.1, and 2.1 times higher than the values obtained from the FK, KTP, and square tube. Under axial compression, the foot like supports stabilized the inner rectangular tube and activated a unique plastic hinge evolution mode in which the hinge lines were parallel to the loading direction. This mechanism significantly improved the crashworthiness of the structure. Parametric studies on wall thickness, polygonal number, and height to width ratio identified an optimal configuration that provided enhanced stability and energy dissipation. Low velocity drop weight tests further confirmed the superior impact resistance and stable dynamic deformation of the KHS. A metal and nonmetal hybrid configuration that combines a metallic mesh with PLA was also investigated. The hybrid layer effectively suppressed fracture and delamination during impact and improved the structural integrity of the KHS. Overall, the KHS provides a lightweight, efficient, and reliable solution for impact mitigation in aerospace structures, offering strong potential for integration into next-generation aircraft and spacecraft protection systems.