bTeam Utilizing techniques inspired by Japanese paper-cutting, the researchers have developed robust metal lattices that surpass cork in both weight and customizable mechanical attributes. Cellular solids, resembling honeycombs, derive their mechanical properties from the configuration of their constituent cells, influencing characteristics like stiffness and strength. Natural examples like bones exemplify this concept, possessing both lightness and durability.
Emulating nature’s cellular solids, humans have adapted these principles to engineer architected materials. By manipulating the geometry of the unit cells comprising these materials, scientists can tailor their mechanical, thermal, or acoustic features. Architected materials find application in a wide range of fields, from shock-absorbent packaging foam to heat-regulating radiators.
MIT’s Innovation in Architected Materials
MIT researchers have achieved a groundbreaking development in architected materials, employing kirigami, an ancient Japanese art of folding and cutting paper, to create high-performance plate lattices on a larger scale than previously attainable through additive manufacturing techniques. This methodology allows for the fabrication of these structures using various materials, each tailored to specific shapes and mechanical properties.
Described as “steel cork,” this material combines the lightweight properties of cork with exceptional strength and stiffness. Professor Neil Gershenfeld, leading MIT’s Center for Bits and Atoms, expresses enthusiasm for this advancement.
The research team devised a modular construction process involving the formation, folding, and assembly of numerous smaller components into 3D structures. This approach enabled the creation of ultralight and ultrastrong structures and robots that maintain their shape under specified loads.
Due to their combination of lightweight properties, strength, stiffness, and scalability, these structures hold immense potential in architectural, aerospace, automotive, and aviation applications.
Innovative Fabrication Through Folding
Architected materials like lattices are often employed as cores in sandwich structures, as seen in aircraft wings. Traditional truss lattices employ intersecting diagonal beams to create a lattice core, which is then sandwiched between top and bottom panels, providing high strength and stiffness with minimal weight.
Plate lattices, however, consist of three-dimensional plate intersections, surpassing truss lattices in strength and stiffness but presenting fabrication challenges, particularly for large-scale applications.
MIT researchers overcame these challenges by employing kirigami, which typically involves partially folded zigzag creases to produce plate lattices. To create sandwich structures, flat plates must be attached to the corrugated core using adhesives or welding, a cumbersome process. The team modified a common origami crease pattern, the Miura-ori, to transform the corrugated structure’s sharp points into facets. These facets facilitated easier attachment of plates using bolts or rivets.
Additionally, the researchers designed, folded, and cut the pattern to control mechanical properties such as stiffness, strength, and flexural modulus. This information, along with the desired 3D shape, was encoded into a creasing map used to create the kirigami corrugations. The flexibility of the structure allowed for precise control over deformation in different areas, making it suitable for dynamic applications like robots.
To create larger structures, the team employed a modular assembly process, mass-producing smaller crease patterns and assembling them into ultralight and ultrastrong 3D structures. This approach simplified manufacturing for smaller structures with fewer creases.
Achieving Record Material Properties
Using their adapted Miura-ori pattern, the researchers produced aluminum structures with a compression strength exceeding 62 kilonewtons, yet weighing only 90 kilograms per square meter, lighter than cork at approximately 100 kilograms per square meter. These structures demonstrated the ability to withstand three times the force of typical aluminum corrugations.
This versatile technique can be applied to various materials, including steel and composites, making it ideal for lightweight, shock-absorbing components in aerospace, automotive, and other industries. To facilitate its application, the team plans to develop user-friendly CAD design tools and reduce computational costs for simulating designs with desired properties.
Art and Functionality in Architected Materials
Kirigami corrugations hold immense potential for architectural construction, offering innovative solutions that reduce material waste and enable higher-performing and more expressive buildings. The technology’s impact extends beyond aerospace and automotive industries.
In a creative endeavor, MIT graduate students utilized this technique to craft large-scale, folded artworks from aluminum composite, highlighting the aesthetic possibilities inherent in their mathematical and engineering contributions. The fusion of art and utility signifies the transformative potential of kirigami corrugations.
Reference: “Kirigami Corrugations: Strong, Modular, and Programmable Plate Lattices” by Alfonso Parra Rubio, Klara Mundilova, David Preiss, Erik D. Demaine, and Neil Gershenfeld, DETC2023.PDF. This research received funding from the Center for Bits and Atoms Research Consortia, AAUW International Fellowship, and GWI Fay Weber Grant.
