Finding new angles on an old artform, McGill researchers have increased the number of stable shapes that kirigami-based engineered materials can take, opening the way to a range of new applications.
What makes these metamaterials special is not what they are made of - they can be plastic, cardboard or anything else - but how, thanks to shapes cut into them, they are able to morph from one form to another. To begin to understand the concept, think of pop-up illustrations of cut paper in books or greeting cards.
Drawing inspiration from kirigami, the Japanese art of paper cutting, and using laser cutters on such materials as plastic, the researchers explored the interior geometry, such as the angles, of the triangles that serve as the basis for the kirigami forms.
Current kirigami patterns when deployed undergo uniform scaling, meaning for example that a square shape grows in size to become a larger square. What the researchers have done is to enable a square shape to transform into other forms, such as a rectangular or trapezoidal shape. This is known as arbitrary scaling, leading to what is sometimes referred to as anisotropic morphing.
As a result, the McGill team has significantly expanded the number of stable yet morphable shapes that can serve as the building blocks for new metamaterials that arbitrarily scale during morphing. The researchers say their discovery could lead to the creation of new products in fields ranging from soft robotics and wearable technologies to deployable structures. They have already filed some patent applications based on their discoveries.
"Once pulled, these kirigami shapes with slits can stretch and, if rationally designed, can transform into other shapes that retain their forms of equilibrium. This opens the door to the creation of objects that can save storage space in one form and morph into another shape to fulfill different functions," explained Damiano Pasini, the Canada Research Chair in Mechanical Metamaterials and a professor in the McGill University's Department of Mechanical Engineering. He is the corresponding author of a recent paper on the subject in Advanced Materials.
"As a result, a single piece of material with rationally designed slits can offer versatility, anisotropic morphing and multi-functionality that is not seen in conventional materials." He said the development has been attracting considerable attention from the world of science and technology.
"While this work offers a foundational understanding of the physical mechanisms involved in the formation of multi stable forms with distinct degrees of anisotropic deployment and opens a new world of possibilities, it is not tied to a specific application," Pasini said. "Our next step is to work on applications in everyday technology."
The paper
"Anisotropic morphing in bistable kirigami through symmetry breaking and geometric frustration" by Chuan Q, Agnelli F, Pokkalla DK, D'Ambrosio N, Pasini D, was published in Advanced Materials
https://doi.org/10.1002/adma.202313198
The funding
The research was funded by the Canada Research Chairs Program, the Natural Sciences and Engineering Research Council of Canada and MITACS, the Fundamental Research Funds for the Central Universities and the National Natural Science Foundation of China.
Images available on request
