Imagine a house that will fit into a rucksack or a wall that turns into a window at the flick of a button. In principle, both of these could be possible, thanks to a new material under development by researchers at Harvard University, with help from TU Delft. This highly versatile material is foldable and its shape and size can be adjusted.
The Delft connection
The first author of the article in Nature Communications is Johannes Overvelde, a doctoral candidate at Harvard University who graduated with a Master’s in TU Delft’s 3mE faculty. He was assisted in his research by Twan de Jong, Master’s student of Aerospace Engineering at TU Delft. ‘We’ve designed a new, advanced meta-material inspired by modular origami,’ says Overvelde. ‘Its shape, volume and stiffness can be dramatically altered thanks to built-in actuators.’
The structure is inspired by an origami technique called snapology and is made from extruded cubes with 24 faces and 36 edges. Like origami, the cube can be folded along its edges to change shape. The researchers used a prototype to demonstrate, both theoretically and experimentally, that the cube can be deformed into many different shapes by folding certain edges, which act like hinges.
The cubes are made of ultra-thin layers of PET plastic and double-sided tape. The actuation is made using a plastic known as PVC. The researchers embedded pneumatic actuators into the structure, which can be programmed to change the cube’s shape and size. The material can be embedded with any kind of actuator, including thermal, dielectric or even water.
The team connected 64 individual cells to create a 4x4x4 cube that can grow and shrink and even folds completely flat. As the structure changes shape, its stiffness also changes dramatically.
Portable pop-up domes
According to Harvard University, the development opens up new design opportunities for these easily-deployable transformable structures, for example in dynamic architecture, such as adaptive building façades and retractable roofs.
‘This research demonstrates a new class of foldable materials that is also completely scalable,’ says Overvelde. ‘The principle works from the nanoscale to the metre-scale and could be used to make anything from surgical stents to portable pop-up domes for disaster relief.’
TU Delft’s Twan de Jong worked on the prototypes used in the research and conducted the experiments. He is not the first Master’s student from Delft to work on this subject as a visiting student at Harvard. Last year, Overvelde published in the journal PNAS about an earlier, related project on the use of instability in soft actuators, in which two TU Delft Master’s students were also involved.
Article:“A three-dimensional actuated origami-inspired transformable metamaterial with multiple degrees of freedom”, Nature Communications 11 March 2016. (DOI: 10.1038/NCOMMS10929).
Press release from Harvard University ‘Transforming materials: Harvard researchers design 3-D material with controllable shape and size.’