A smashing success: Understanding the compression of origami structures

When most materials are squished in one dimension, they expand in the other dimensions. Auxetic materials, however, contract laterally. This property — which enhances resistance against shear deformation and improves fracture toughness and energy absorption efficiency — makes auxetic metamaterials good candidates for engineering applications.

Since origami-based lattice objects have been found to be efficient structures for harnessing auxetic properties, Tomita et al. chose to investigate how using functionally graded thickness can affect the mechanical properties, like buckling behavior and force responses, of these structures.

For the study, the researchers used a type of origami-based lattice known as the Tachi-Miura polyhedral, which had previously been studied for its auxetic properties. The team constructed test objects with a 3D-printer using commercially available materials. The test objects had functionally graded thickness, meaning each layer was successively thinner than the one below it. They submerged the materials in water to prevent fracturing during testing then they impacted the structure while making observations with a high-speed camera.

“We are excited to find that the graded thickness maintains the auxetic deformation of origami lattices through large deformations and achieves non-uniform force responses,” said coauthor Sunao Tomita. “Such non-uniform responses are often required in engineering applications for impact protection.”

The results showed the graded thickness allowed for a range of buckling behaviors and force responses. In addition, experimental results suggest these graded thickness materials could be useful for cushioning structures as they remain strong after dynamic and repetitive loading. The researchers intend to continue optimizing the structure’s performance and control other properties such as acoustics and heat transfer.

Source: “Control of buckling behavior in origami-based auxetic structures by functionally graded thickness,” by S. Tomita, K. Shimanuki, and K. Umemoto, Journal of Applied Physics (2024). The article can be accessed at https://doi.org/10.1063/5.0194238 .

This paper is part of the Physics of 3D Printing Collection, learn more here .