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

Victoria D. Doty

Engineers at Caltech and JPL have formulated a content impressed by chain mail that can completely transform from a foldable, fluid-like condition into distinct solid designs below force.

The content has potential programs as a sensible fabric for exoskeletons, or as an adaptive forged that adjusts its stiffness as an personal injury 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 Utilized Physics and corresponding creator of a analyze describing the content that was released in Nature.

“We wished to make supplies that can modify stiffness on command,” Daraio claims. “We’d like to create a fabric that goes from smooth and foldable to rigid and load-bearing in a controllable way.” An case in point from well known culture would be Batman’s cape from the 2005 movie Batman Commences, which is usually versatile but can be manufactured rigid at will when the Caped Crusader needs it as a gliding surface area.

A content manufactured from linked octahedrons. Graphic credit history: Caltech

Elements that modify houses in very similar techniques by now exist all about us, Daraio notes. “Think about coffee in a vacuum-sealed bag. When continue to packed, it is solid, by using a approach we get in touch with ‘jamming.’ But as soon as you open the deal, the coffee grounds are no extended jammed in opposition to every other and you can pour them as though they ended up a fluid,” she claims.

Personal coffee grounds and sand particles have intricate but disconnected designs, and can only jam when compressed. Sheets of linked rings, having said that, can jam alongside one another below both of those compression and tension (when pushed alongside one another or pulled apart). “That’s the critical,” Daraio claims. “We tested a range of particles to see which ones presented both of those adaptability and tunable stiffness, and the ones that only jam below 1 form of pressure tended to accomplish badly.”

To discover what supplies would operate ideal, Daraio, alongside one another with former Caltech postdoctoral researcher Yifan Wang and former Caltech graduate university student Liuchi Li (PhD ’19) as co-guide authors of the Nature paper, created a range of configurations of linked particles, from linking rings to linking cubes to linking octahedrons (which resemble two pyramids linked at the foundation). The supplies ended up 3-D printed out of polymers and even metals, with assist from Douglas Hofmann, principal scientist at JPL, which Caltech manages for NASA. These configurations ended up then simulated in a computer with a model from the group of José E. Andrade, the George W. Housner Professor of Civil and Mechanical Engineering and Caltech’s resident skilled in the modeling of granular supplies.

Tests the influence resistance of the content when unjammed (smooth). Graphic credit history: Caltech

“Granular supplies are a stunning case in point of intricate units, wherever very simple interactions at a grain scale can guide to intricate conduct structurally. In this chain mail application, the ability to have tensile masses at the grain scale is recreation changer. It’s like possessing a string that can have compressive masses. The ability to simulate such intricate conduct opens the door to extraordinary structural design and style and functionality,” claims Andrade.

The engineers applied an outdoors pressure, compressing the materials using a vacuum chamber or by dropping a bodyweight to control the jamming of the content. In 1 experiment, a vacuum-locked chain mail fabric was in a position to assistance a load of one.five kilograms, extra than 50 moments the fabrics’ very own bodyweight. The materials that showed the greatest versions in mechanical houses (from versatile to rigid) ended up all those with larger sized ordinary range of contacts in between particles, such as linked rings and squares, akin to medieval chain mail.

“These materials have potential programs in sensible wearable tools: when unjammed, they are light-weight, compliant, and cozy to put on following the jamming transition, they develop into a supportive and protecting layer on the wearer’s overall body,” claims Wang, now an assistant professor at Nanyang Technological University in Singapore.

In the case in point of a bridge that could be unrolled and then driven across, Daraio envisions jogging cables as a result of the content 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 opportunities.

When stiffened, the content has the potential to act as a durable bridge. Graphic credit history: Caltech

In parallel operate on so-referred to as sensible surfaces, which are surfaces can modify designs to distinct configurations at will, Daraio, alongside one another with postdoctoral scholar Ke Liu and traveling to university student Felix Hacker, not long ago demonstrated a approach for controlling the condition of a surface area by embedding networks of heat-responsive liquid crystal elastomers (LCEs), slim strips of polymer that shrink when heated. These LCEs include stretchable heating coils that can be billed with electrical current, which heats them up and leads to them to deal. As the LCEs contracted, they tugged at the versatile content into which they ended up embedded and compressed it into a predesigned solid condition.

That operate, which was released in the journal Science Robotics, could be handy for remote collaboration wherever a physical component of the collaboration is needed, clinical units, and haptics (which use technology to simulate physical feeling for digital truth). Upcoming, the staff plans to miniaturize and improve the design and style of both of those structured materials and sensible units to get them nearer to simple programs.

Created by Robert Perkins

Source: Caltech

 


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