Kirigami Design and Modeling for Strong, Lightweight Metamaterials

Significance 

Mechanical metamaterials are artificial structures with mechanical properties derived from the unit cell geometry instead of the base materials. Moreover, counterintuitive mechanical properties like high strength, lightweight and negative Poisson’s ratio can be realized by adopting lattices and shells. Although mechanical metamaterials can be fabricated via additive manufacturing techniques with high fidelity, efficiency is often lost. Lately, the art of paper cutting (known as kirigami) has emerged as an alternative solution for designing and fabricating mechanical metamaterials. Generally, kirigami is an extended version of origami (paper folding).

Over the years, kirigami and origami techniques have become attractive ways of designing lightweight materials and deployable structures. They enable low-cost and high-efficiency fabrication of metamaterials, including complex three-dimensional geometries. However, most of the existing kirigami designs focus on kinematic patterns where the function is highly influenced by the motion in the folded state. However, practical applications like biomedical implants and industrial weight reduction require lightweight and strong metamaterials to meet the low-mass and high-strength needs. Unfortunately, research on lightweight and strong origami/kirigami metamaterials is limited.

Kinematic origami patterns generally produce increased stiffness due to the interlocking folds. However, these patterns require constraints or external frames to maintain their folded configuration. Despite remarkable progress in developing kirigami techniques, a comprehensive study of kirigami designs for shape morphing as well as their characterization and mechanical application under loaded conditions, is still lacking. Although sealing the collocate cuts in folded configuration could achieve high payload capability, the ability to sustain compression loads is yet to be verified.

The design of robust kirigami metamaterial that can be transformed into arbitrary complex objects faces three crucial challenges: difficulty in inventing kirigami pattern of unit cells to achieve lightweight and strong metamaterials, developing an effective algorithm for automated transformation and designing gluing connector to ensure high strength. To overcome these limitations, Dr. Hongying Zhang from the National University of Singapore and led by Professor Jamie Paik from Reconfigurable Robotics Lab at EPFL (École Polytechnique Fédérale de Lausanne) in Switzerland developed a novel kirigami-based scheme for designing and modeling strong and lightweight metamaterials. Their work is currently published in the research journal, Advanced Functional Materials.

In their approach, the authors proposed a checkerboard kirigami metamaterial with mechanical connectors. The shape-transforming and mechanical strength of checkerboard kirigami were discussed. The kirigami patterns were created by creasing the designed folds and cuts on a planar sheet and folding it on checkerboard patterns with pop-down and pop-up blocks. A computational algorithm involving the deployment of the discretized 3D objects on planar sheets was adopted for automatic shape-transformation.

The authors conducted standard compression tests and demonstrated that a kirigami metamaterial weighing 12.05 g could carry 346.4 N payloads. The improved robustness and high strength were attributed to the design of a glue-free mechanical connector capable of locking the collocated cuts in the folded configuration. Based on this design, six curved surfaces were prototyped to validate the automatic shape transforming capability of the proposed metamaterial. The folding and cutting patterns for the flat and curved surfaces were automatically achieved using the computational model.

In summary, Dr. Hongying Zhang and Professor Jamie Paik reported a novel design of kirigami metamaterials capable of withstanding high loads. The proposed kirigami metamaterial design and modeling could effectively sustain high payloads and fortify flat and curved shapes and topologies, making up complex three-dimensional objects in various applications. The results implied that the adopted design could be extended to other materials to achieve optimized weight, strength and functionality. In a statement to Advances in Engineering, Professor Jamie Paik, the corresponding and lead author stated that their findings would pave the way for widespread adoption of kirigami metamaterials in diverse industrial applications requiring high strength and weight reduction.

Kirigami Design and Modeling for Strong, Lightweight Metamaterials - Advances in Engineering Kirigami Design and Modeling for Strong, Lightweight Metamaterials - Advances in Engineering Kirigami Design and Modeling for Strong, Lightweight Metamaterials - Advances in Engineering Kirigami Design and Modeling for Strong, Lightweight Metamaterials - Advances in Engineering Kirigami Design and Modeling for Strong, Lightweight Metamaterials - Advances in Engineering Kirigami Design and Modeling for Strong, Lightweight Metamaterials - Advances in Engineering Kirigami Design and Modeling for Strong, Lightweight Metamaterials - Advances in Engineering Kirigami Design and Modeling for Strong, Lightweight Metamaterials - Advances in Engineering

About the author

Prof. Jamie Paik
Director of Reconfigurable Robotics Laboratory
Ecole Polytechnique Federale de Lausanne (EPFL)
Email : [email protected]
Twitter: @robotician
Linkedin: https://www.linkedin.com/in/jamiepaik/

Prof. Jamie Paik is director and founder of Reconfigurable Robotics Lab (RRL) of Swiss Federal Institute of Technology (EPFL) and a core member of Swiss National Centers of Competence in Research (NCCR) Robotics consortium. RRL’s research leverages expertise in multi-material fabrication and smart material actuation toward unique robotic platforms. At Harvard Microrobotics Laboratory, she started developing unconventional robots that push the physical limits of material and mechanisms. Her latest research effort is in soft robotics and self-morphing Robogami (robotic origami). Robogami transforms autonomously its planar shape to 2D or 3D by folding in predefined patterns and sequences, just like the paper art, origami. Soft material robots and robogamis are designed to be interactive with the users and their environments through both innate and active reconfigurations. Such characteristics of the RRL’s robots have direct applications in medical, automobile, space, and wearable robots. While this novel technology has been published in multiple academic journals such as in Soft Robotics Journal, IEEE Transactions in Robotics, Nature, and Science, RRL’s spin-off, Foldaway-Haptics, has pushed the boundaries of the industrial applications of these robots as seen in TED conference 2019. The latest robogami is part of Mercedez’s 2020 concept car, Avatar, presented during CES 2020.

About the author

Dr. Hongying Zhang
Lecturer, Department of Mechanical Engineering, National University of Singapore
Email: [email protected]
Tel: +65 6601 2547
Address: Block E1, 3 Engineering Drive 2, #08-15, National University of Singapore, Singapore 117578
Google Scholar: https://scholar.google.com.sg/citations?user=Gzu-S2sAAAAJ&hl=en

Dr. Hongying Zhang is a lecturer at the Department of Mechanical Engineering, National University of Singapore. Dr. Zhang started her undergraduate education at the Huazhong University of Science and Technology (HUST), China, and received a B.S. degree in Mechanical Engineering in 2013. She began her doctoral research at the Chinese University of Hong Kong (CUHK) in the same year. Following her research supervisor, she then joined the National University of Singapore (NUS) to continue her Ph.D. study in 2014 after a year of study in Hong Kong. At NUS, she worked on design, analysis, and manufacturing of topology-optimized soft robots and wearable dielectric sensors. Sponsored by the Facebook Virtual Reality Lab, Dr. Zhang joined Prof. Jamie Paik’s group (Reconfigurable Robotics Laboratory) at the École Polytechnique Fédérale de Lausanne (EPFL) as a postdoctorate researcher in 2018. At EPFL, Dr. Zhang has led the work on developing methodologies to analyze novel origami robots, and designing kirigami-inspired metamaterials. Dr. Zhang has multiple publications in high-impact journals and conferences including Advanced Functional Materials, Soft robotics, IEEE/ASME Transactions on Mechatronics, Materials and Design, ICRA, IROS, etc.

Reference

Zhang, H., & Paik, J. (2022). Kirigami Design and Modeling for Strong, Lightweight MetamaterialsAdvanced Functional Materials, 32(21), 2107401.

Go To Advanced Functional Materials

Check Also

Numerical investigation on melting behaviour of phase change materials/metal foam composites under hypergravity conditions