Material Inspired by Chain Mail Transforms from Flexible to Rigid on Command

Nancy J. Delong

Engineers at Caltech and JPL have developed a substance inspired by chain mail that can completely transform from a foldable, fluid-like condition into unique good styles below strain.

The substance has prospective programs as a intelligent fabric for exoskeletons, or as an adaptive solid that adjusts its stiffness as an damage heals, or even as a deployable bridge that could be unrolled and stiffened, according to Chiara Daraio, Caltech’s G. Bradford Jones Professor of Mechanical Engineering and Applied Physics and corresponding writer of a review describing the substance that was released in Character.

“We preferred to make materials that can transform stiffness on command,” Daraio claims. “We’d like to develop a fabric that goes from delicate and foldable to rigid and load-bearing in a controllable way.” An example from well-liked tradition would be Batman’s cape from the 2005 movie Batman Begins, which is typically flexible but can be built rigid at will when the Caped Crusader demands it as a gliding surface.

A substance built from joined octahedrons. Graphic credit: Caltech

Resources that transform attributes in identical strategies presently exist all about us, Daraio notes. “Think about espresso in a vacuum-sealed bag. When nonetheless packed, it is good, via a approach we get in touch with ‘jamming.’ But as shortly as you open up the bundle, the espresso grounds are no for a longer time jammed from every other and you can pour them as although they were being a fluid,” she claims.

Individual espresso grounds and sand particles have intricate but disconnected styles, and can only jam when compressed. Sheets of joined rings, nevertheless, can jam alongside one another below both compression and tension (when pushed alongside one another or pulled aside). “That’s the vital,” Daraio claims. “We tested a range of particles to see which ones presented both adaptability and tunable stiffness, and the ones that only jam below one particular form of tension tended to conduct poorly.”

To discover what materials would function finest, Daraio, alongside one another with previous Caltech postdoctoral researcher Yifan Wang and previous Caltech graduate scholar Liuchi Li (PhD ’19) as co-direct authors of the Character paper, created a range of configurations of joined particles, from linking rings to linking cubes to linking octahedrons (which resemble two pyramids related at the foundation). The materials were being 3-D printed out of polymers and even metals, with help from Douglas Hofmann, principal scientist at JPL, which Caltech manages for NASA. These configurations were being then simulated in a computer with a model from the team of José E. Andrade, the George W. Housner Professor of Civil and Mechanical Engineering and Caltech’s resident expert in the modeling of granular materials.

Tests the affect resistance of the substance when unjammed (delicate). Graphic credit: Caltech

“Granular materials are a wonderful example of intricate units, where simple interactions at a grain scale can direct to intricate habits structurally. In this chain mail application, the skill to carry tensile loads at the grain scale is video game changer. It’s like possessing a string that can carry compressive loads. The skill to simulate this sort of intricate habits opens the doorway to extraordinary structural design and style and effectiveness,” claims Andrade.

The engineers applied an outside the house tension, compressing the fabrics applying a vacuum chamber or by dropping a bodyweight to handle the jamming of the substance. In one particular experiment, a vacuum-locked chain mail fabric was capable to assist a load of one.five kilograms, more than 50 instances the fabrics’ possess bodyweight. The fabrics that confirmed the largest variations in mechanical attributes (from flexible to rigid) were being people with larger sized average range of contacts in between particles, this sort of as joined rings and squares, akin to medieval chain mail.

“These fabrics have prospective programs in intelligent wearable devices: when unjammed, they are lightweight, compliant, and snug to put on following the jamming changeover, they turn out to be a supportive and protective layer on the wearer’s overall body,” claims Wang, now an assistant professor at Nanyang Technological University in Singapore.

In the example of a bridge that could be unrolled and then pushed throughout, Daraio envisions operating cables via the substance that then tighten to jam the particles. “Think of these cables like the drawstrings on a hoodie,” she claims, noting that she is now checking out this cable plan and other prospects.

When stiffened, the substance has the prospective to act as a durable bridge. Graphic credit: Caltech

In parallel function on so-known as intelligent surfaces, which are surfaces can transform styles to unique configurations at will, Daraio, alongside one another with postdoctoral scholar Ke Liu and browsing scholar Felix Hacker, not long ago shown a method for managing the condition of a surface by embedding networks of heat-responsive liquid crystal elastomers (LCEs), slim strips of polymer that shrink when heated. These LCEs consist of stretchable heating coils that can be billed with electrical present, which heats them up and triggers them to contract. As the LCEs contracted, they tugged at the flexible substance into which they were being embedded and compressed it into a predesigned good condition.

That function, which was released in the journal Science Robotics, could be beneficial for remote collaboration where a bodily component of the collaboration is important, clinical units, and haptics (which use know-how to simulate bodily feeling for digital actuality). Upcoming, the team programs to miniaturize and optimize the design and style of both structured fabrics and intelligent units to get them closer to useful programs.

Composed by Robert Perkins

Supply: Caltech


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