3D Fabric Printing Moves Up A Gear As Scientists From Caltech And NTU Singapore Create A Novel Programmable Protective Textile
Scientists from NTU Singapore and the California Institute of Technology (Caltech), United States, have developed a new type of ‘chain mail’ fabric that is flexible like cloth but can stiffen on demand.
For its 3D-printing operation Caltech TechLab currently has 13 CraftUnique CraftBot Plus FFF/FDM 3D printers in operation using exclusively 1.75mm PLA filament, from this department novel uses and structures of 3D textiles are investigated.
The lightweight fabric is 3D-printed from nylon plastic polymers and comprises hollow octahedrons (a shape with eight equal triangular faces) that interlock with each other. When encased in a plastic envelope and vacuum-packed, it becomes 25 times more rigid and can hold up over 50 times its own weight.
This next-generation fabric paves the way for lightweight armour that can harden to protect a user against an impact, protective gear for athletes, and exoskeletons that can help the elderly to stand, walk and carry objects.
Published in Nature, this interdisciplinary research results from a collaboration between experts in mechanical engineering and advanced manufacturing.
Moving forward, the team is looking to improve the material and fabric performance of their chain mail and to explore more methods of stiffening it, such as through magnetism, electricity or temperature.
The material has potential applications as a smart fabric for exoskeletons, or as an adaptive cast that adjusts its stiffness as an 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 Applied Physics and corresponding author of a study describing the material that was published in Nature on August 11.
"We wanted to make materials that can change stiffness on command," Daraio says. "We'd like to create a fabric that goes from soft and foldable to rigid and load-bearing in a controllable way."
An example from popular culture would be Batman's cape from the 2005 movie Batman Begins, which is generally flexible but can be made rigid at will when the Caped Crusader needs it as a gliding surface.
Materials that change properties in similar ways already exist all around us, Daraio notes. "Think about coffee in a vacuum-sealed bag. When still packed, it is solid, via a process we call 'jamming.' But as soon as you open the package, the coffee grounds are no longer jammed against each other and you can pour them as though they were a fluid," she says.
Their work has systematically explored the mechanics of structured fabrics consisting of non-convex interlocked particles with precisely controlled geometry, during the jamming transition.
Reconfigurable fabrics composed of discrete particles can be realized at different scales, because the jamming transition is a scale-invariant physical phenomenon.
Recent advances in additive manufacturing make it possible, in principle, to scale the fabric thickness from the micrometre to the metre scales, and to use different constitutive materials, targeting different applications.
With the integration of alternative methods for confinement (for example, electrical or magnetic control), it is possible to envision programming stiffness at different locations within the fabrics, for applications such as haptic interfaces and medical stimulation.
