Following the Thread: Drexel’s TopoKnit System Lays the Foundation for Universal Functional Fabric Design | Now

Drexel’s Topoknit program can trace the path of yarn through knitted material, which is a crucial step in the effective design and creation of functional fabrics.

Before 3D printing, CNC routing, laser cutting, and ubiquitous “crafting” tools, there was the needle and the thread. For centuries, early makers knit things. Blankets, sweaters, gloves – everything took shape by combining just a handful of basic stitches. Now, a team of researchers from Drexel University are translating these loops and twists into a digital architecture of knitting – a key step in the process of integrating new technologies into textiles.

While the promise of textile-integrated technology, or “functional fabrics,” has loomed on the horizon for decades, it has mostly come to fruition in the form of technical and high-performance military gear and fashion concepts. top of the line. In most of these garments, the technology is an external addition, rather than an integrated feature, of the design.

According to David Breen, PhDprofessor at Drexel’s College of Computing & Informatics who has been modeling fabrics since the 1990s, is that current software used for industrial textile design and production lacks the yarn-level detail needed for digital sampling and fabric manufacturing. precision of fabric devices.

“So that these [technical] For textiles to be widely deployed and reach their full industrial potential, computerized modeling and simulation tools must be developed to support the design and optimization of knitted structures,” Breen’s group wrote in a recent paper in the review Graphic models.

The piece featured TopoKnit, a suite of algorithms they developed as a tool to model the path of a yarn in a knitted textile. Although it does not solve the entire modeling challenge, the program provides an essential part of the design process: documentation of how parts fit together to form a finished part – the equivalent of a blueprint architecture.

topoknit graph

Topoknit was created to plot yarn positioning in knitted materials as a tool for predictive modeling, design and creation of new functional fabrics.

TopoKnit translates stitch commands – like knit, purl and transfer – as they would appear in a knitting pattern, or the program of a digital knitting machine, into a map that shows where the yarn is moving , loop by loop, and how it interacts with adjacent loops as the textile is formed. The resulting diagram, called a topology graph, allows designers to determine where a piece of yarn is, relative to the overall plane of the textile, at any given point within it.

Building up this basic design information for knitting comes at a time when more researchers are considering knits to make functional fabrics. Breen suggests this is partly because knitting supports more complex yarn interactions than weaving, which is advantageous for creating electrical circuits. Additionally, knitting allows for more controllable design touchpoints, as well as the ability to generate 3D shapes without additional manufacturing steps, such as cutting and sewing.

“The interesting thing about knitting is that at the knit level, it has a fully programmable microstructure. Knitting is a kind of programming that associates stitch operations with specific physical structures. said Breen. “Because the loops form many different connections, knitting is more complex than weaving. Knitted fabrics have always been more difficult to model than woven fabrics. But it gives designers more entry points to manipulate various aspects of the material, which makes it very promising for integrating new features.

To put TopoKnit to the test, Breen PhD student Levi Kapllani Maharaj worked with research partners and designers from Drexel’s Center for Functional Fabrics to generate a series of 100 patterns of 5×5 stitch configurations using of the graphical interface of one of the Centre’s digital knitting machines. The same stitch commands that were entered into the machine were also entered into TopoKnit to produce a topology graph. The team compared each graph to its corresponding rendered graph to see if the dot map matched the rendered model.

topoknit topology graph

The Topoknit program can plot the overlay of knitted materials.

The graphs matched exactly in each case, showing that the TopoKnit system could be used to reliably produce manufacturing instructions for knitted textiles through a sequence of steps that produces specific yarn topologies. These topologies, descriptions of how the wires contact and interconnect, allow the system to point out the dot patterns in a design that would not be viable in production, which is an important step for prototyping.

While TopoKnit’s accuracy is important, Breen noted that it’s still only the first of many steps toward a textile modeling program that can represent and simulate functional fabrics.

For any type of high-level computer modeling, a topology graph is the foundation upon which more visible features, such as shape, force, and motion, are built. But for textiles, that base was never established, because the process of making products was usually more urgent than redesigning them for high-performance tools.

“It’s ironic that fabric is one of the oldest materials created by man, but modeling it has proven to be extremely difficult and computationally expensive.” said Breen. “Steel beams are easier to study and model than knitted fabrics: because fabrics stretch and twist, they require a lot of computing power when modeled in the same way as this steel beam .”

Despite this technical disconnect, research and development around functional fabrics has gained momentum primarily due to government projects focused on specific performance goals, such as the integration of communication or vital signs monitoring technology. in military uniforms. But to do this, the field has relied heavily on the expertise of individual designers and makers with extensive knitting experience.

The advantage of enhanced textile design platforms, Breen suggested, is that they would open up textile design to people with expertise in other fields, such as electrical engineering or materials science. Topoknit is a technology independent approach to developing interoperability tools between machines and modeling platforms. And because it would allow designers to try new approaches with a better assessment of what will work – rather than spending time and resources on trial and error – better modeling should allow for more property-related efforts. of consumption.

“Some of these materials are very expensive. You can’t afford to do trial and error because of the limited supply of some of these advanced fibers and yarns,” he said. “The vision of computer-aided design is that you model, simulate, and explore the design space. You do all of this virtually, computationally, so you don’t have to go through the expensive process of doing it and then see if it works. Or you could at least explore the design options and refine the tests you want to do with the finished part.

Textile MXene

Being able to trace the path of yarn in a knitted textile will allow designers to incorporate features, like electrical circuits, into knitted materials with predictable and repeatable results.

Building on the topological framework provided by TopoKnit, the next step of this research is to optimize the shape and behaviors of knitted textiles. Ensuring accuracy and shape modeling will prime computer programs to meticulously reproduce the mechanical properties of textiles and ultimately direct knitting machines to produce textiles with specific performance capabilities.

“If we want to see the potential of functional fabrics fully realized, we need to get to the point where knitting is even easier than 3D printing – where you can put in all the parameters you want from size and shape to flexibility and thermal or electrical conductivity and hit ‘go’ and a knitting machine will produce it.This work puts us on the path to that reality.

In addition to Breen and Kapllani Maharaj; Genevieve Diondirector of Drexel’s Center for Functional Fabrics; Chelsea Amanatides, PhD, senior research engineer at the Centre; and Vadim Shapiro, PhD, from the University of Wisconsin contributed to the development of TopoKnit. The project was originally funded by the National Science Foundation.

Read the full article here: https://www.sciencedirect.com/science/article/abs/pii/S1524070321000199

Abdul J. Gaspar