Computer numerical control (CNC) knitting technology offers great potential for the creation of thermoformable textiles that can be shaped and stiffened in response to heat. This research explores how CNC knitting can be used to design and fabricate textiles with precisely allocated material and microstructure layouts. These layouts pre-program specific deformation mechanism(s) into the textile that bias it to form an intended geometry, forgoing the need for a mould during the thermoforming process.

The textiles are fabricated by knitting two thermal-reactive yarns with different extents of shrinkage in a double layered structure akin to a bilayer strip. A computational design-to-fabrication pipeline translates raster images into machine-knittable instructions. Referencing multi-material additive manufacturing principles and self-actuating textiles, several design strategies to convert input pixel data into a material distribution layout are proposed, namely dithered gradients, tessellated patches, and origami creases. When paired with an assisted thermoforming process, these layouts induce specific deformations of the textile, such as uni-axial and multi-axial curling, periodic buckling, and sharp folding. The prototypes implement these strategies on the micro-, meso-, and macroscale.

Further reading:
Tan, Y.Y., Quek, Y.H., Chia, P.Z. and Gupta, U. (2023). Geometric Control of Thermoformable Knitted Textiles Using Raster Images. Smart Materials and Structures, 32(7).