Kirigami sheets absorb impacts better with flexible hinge design
Kirigami Meta-Sheet for Enhanced Impact Absorption
Computational Engineering, Finance, and Science
Summary
Protecting things from impact often uses thick materials that can be hard to make in large sizes. The authors explore using a flat sheet with kirigami cuts—patterns inspired by paper cutting—that changes how it reacts to force, shifting between pushing back strongly and softly. They found that by adjusting the size of the hinges in the pattern, they could control the sheet’s stiffness and improve its ability to absorb shock without breaking. Tests showed this design reduced impact force and rebound better than common materials like foam, even protecting a delicate egg during a drop. Because these sheets are flat, they can be easily produced in large areas using common manufacturing methods.
kirigamimechanical metamaterialsimpact absorptionstiffnessnegative stiffnessmass-spring-damper modelhinge ratioquasistatic indentationdrop-tower testsenergy dissipation
Authors
Dahyun Joo, Yasuhiro Miyazawa, Seokhyeon Hong, Dongha Lee, Jinkyu Yang, Do-Nyun Kim
Abstract
Impact absorbers based on mechanical metamaterials often use bulky, vertically stacked architectures, limiting large area deployment and scalable manufacturing. Here, we propose a kirigami meta-sheet as a planar absorber that uses transitions between positive and negative stiffness regimes rather than sacrificial crushing. Guided by an analysis of a simple mass-spring-damper model, we program the stiffness of kirigami meta-sheets through the hinge ratio connecting the unit cells. Quasistatic indentation experiments confirm that the meta-sheet with a low hinge ratio most clearly exhibits the negative stiffness transition. The drop-tower tests show that it reduces rebound, decreases the first impact force, and increases dissipation. Unlike polyethylene mesh and styrofoam, this kirigami meta-sheet is shown to be effective in protecting a falling egg. Its planar geometry enables area scaling by tiling and is compatible with sheet level manufacturing routes such as cutting, molding, and lamination, establishing kirigami meta-sheets as practical impact absorbers.