A team of researchers from Harvard University have designed a unique type of foldable material that is versatile, tunable and self actuated. The material can be programmed to change its size, volume and shape; and amazingly it can collapse into a flat sheet to withstand the weight of an elephant without breaking, and pop right back up to prepare for the subsequent task.
“We’ve designed a three-dimensional, thin-walled structure that can be used to make foldable and reprogrammable objects of arbitrary architecture, whose shape, volume and stiffness can be dramatically altered and continuously tuned and controlled,” said Johannes T. B. Overvelde, author of the paper, in a news release.
Inspired by an origami technique known as snapology, researchers developed the “metametarial” using extruded cubes with 24 faces and 36 edges, so that the cube, like origami can be folded along its edges to change shape. As MailOnline noted, the technique is also known as unit or modular origami and it involves constructing multiple identical elements and assembling these into a larger model.
The researchers demonstrated, both theoretically and experimentally, that the cube can be deformed and altered into different shapes by folding certain edges, which act like hinges. Moreover, the pneumatic actuators, which they embedded into the structures, can be programmed to deform specific hinges; that is – the actuators allow the base cubes to be folded along one or more edges, changing the cube’s shape and size, and removing the need for external input.
The team took 64 of the individual cells and connected them into a 4x4x4 cube that can grow, shrink, change its shape globally and the orientation of its microstructure and fold completely flat.
As the structure changes its shape, it also changes stiffness, that is – one could make the material very pliable in one shape and very stiff or rigid in another. The team says these actuated changes in physical properties of the material adds a fourth dimension to the material.
“We not only understand how the material deforms, but also have an actuation approach that harnesses this understanding,” said Bertoldi. “We know exactly what we need to actuate in order to get the shape we want.”
As the team noted, the material can be embedded with any kind of actuator, including thermal, dielectric or even water. This gives plenty of potential, such as, in the development of new types of retractable roofs or walls. Other potential uses of this shape-shifting material could be in building of ‘dynamic architecture’ or “shape-shifting cars – that stretch to be more aerodynamic at speed and shrinks whenever needed.
“The opportunities to move all of the control systems onboard combined with new actuation systems already being developed for similar origami-like structures really opens up the design space for these easily deployable transformable structures,” said Weaver.
“This structural system has fascinating implications for dynamic architecture including portable shelters, adaptive building facades and retractable roofs,” said Hoberman. “Whereas current approaches to these applications rely on standard mechanics, this technology offers unique advantages such as how it integrates surface and structure, its inherent simplicity of manufacture, and its ability to fold flat.”
“This research demonstrates a new class of foldable materials that is also completely scalable,” Overvelde said, ” It works from the nanoscale to the meter-scale and could be used to make anything from surgical stents to portable pop-up domes for disaster relief.”
- Source(s): Harvard, MailOnline
- Image: Johannes Overvelde/SEAS
- Reference: A three-dimensional actuated origami-inspired transformable metamaterial with multiple degrees of freedom