Episode 9: Framework designed for programmable 3D woven metamaterials

In this podcast episode, MRS Bulletin's Laura Leay interviews Carlos Portela from the Massachusetts Institute of Technology about his research group’s design and modeling framework for 3D woven metamaterials. The design framework utilizes a graph structure which allows the woven architecture to be tuned, and it is computationally inexpensive so that it can run on a desktop computer. The outputs include files for finite element modeling to test the metamaterial for large deformations, and for 3D printing of the structure. This work was published in a recent issue of Nature Communications.

Transcript

LAURA LEAY: Welcome to MRS Bulletin’s Materials News Podcast, providing breakthrough news & interviews with researchers on hot topics in materials research. My name is Laura Leay.  Additive manufacturing has given rise to increasingly complex structures, leading to advances in metamaterials. These advances have tended to concentrate on high stiffness and high strength architectures. Now a design framework has been developed that concentrates on deformable, woven metamaterials.

CARLOS PORTELA: The motivation really started with textile materials: the notion of having fibers that are intertwined in space and give you some interesting mechanical properties. So this is something that – in my group – we’ve been studying for the last five or so years, but we were missing a key ingredient which was a framework to be able to design them.

LAURA LEAY: That was assistant professor Carlos Portela from MIT. The design framework utilizes a graph structure which allows the woven architecture to be tuned, and it is computationally inexpensive so that it can run on a desktop computer.

CARLOS PORTELA: The graph structure was very simple in the sense that we started with a periodic lattice arrangement and we created a graph out of them. Basically, the nodes or the junctions became the actual nodes where struts would connect in a physical lattice. And then the edges became these features that would carry the parameters for the woven struts. So this the highest level – the first notion of the graph that we use to define the topology. The more interesting… I guess we can call it a sub-graph came to represent the woven nodes. Effectively, if you have a woven strut coming in to another woven strut – we had to find some logic to be able to intertwine these two struts together. And this was done with a separate graph.

LAURA LEAY: Once these graphs are defined for the topology and the nodes, two parameters are defined by the user: the effective radius of the woven-beam helices and the number of turns of a helix. The outputs include files for finite element modelling to test the metamaterial for large deformations, and for 3D printing of the structure. Several previously unachievable structures were fabricated to validate the design framework. The outputs show that a broad range of elastic behaviors can be accurately predicted by varying only the unit cell and strut parameters. The design framework is freely available to download and has multiple applications. Not only could it lead to printable textiles with specifically designed properties, but the highly deformable metamaterial leverages a lot of contact interactions so has the potential to be used as pressure sensors. The framework is also gathering interest among the polymer science community, which leads to an application outside of the metamaterials field.

CARLOS PORTELA: There’s researchers in the polymer science field who look at these metamaterials and think of them as analogue systems to polymer chains at the nanoscale. I think the ideas that have emerged from enabling these kinds of designs is potentially probing different types of polymer network deformation mechanisms. 

LAURA LEAY: The framework could also be used to understand why some polymers are tougher than others. One aspect of the design framework is the incorporation of programmable failure patterns. This means that undesirable failure modes can be avoided or that a failure path could be designed to dissipate energy by forcing a crack to take a more tortuous path. The current research has been validated using 3D printed woven metamaterials fabricated at the microscale, with significant effort put into developing fabrication tools. Now that this groundwork has been laid, future work will move into the macroscale. This work was published in a recent issue of Nature Communications. My name is Laura Leay from the Materials Research Society. For more news, log onto the MRS Bulletin website at mrsbulletin.org and follow us on X, @MRSBulletin. Don’t miss the next episode of MRS Bulletin Materials News – subscribe now. Thank you for listening.