Recoverable 4D-Printed Kirigami Honeycombs with Small-Strain Creases

Four-dimensionally printed polymer honeycombs generally exhibit recoverable deformation only above the glass transition temperature, where their load-bearing capacity is greatly reduced. To address this limitation, this study proposes a recoverable kirigami honeycomb enabled by a small-strain crease design. The original non-Euclidean origami honeycomb is transformed into planar corrugated sheets through local cutting, allowing the structure to be fabricated by 3D printing, folding, and bonding. A geometric model is established to describe the relationship between crease rotation and global honeycomb deformation, revealing that large structural deformation can be achieved with limited local crease strain. Polylactic acid (PLA) specimens with weakened creases are designed and tested to evaluate their shape-memory recovery. The results show that PLA maintains good thermally induced recovery after low-temperature bending, with recovery ratios reaching up to 96.7%. Finite element simulations further confirm that the weakened creases remain within a small strain range even under 180° bending, preventing local failure during large deformation. A stable-state prediction model based on the minimum potential energy principle is developed and validated by experiments and simulations. The predicted stable height agrees well with the experimental result. This work provides a feasible strategy for 4D-printed kirigami honeycombs capable of large deformation below the glass transition temperature followed by thermally activated recovery, with potential applications in deployable structures and temperature-responsive mechanical metamaterials.