A team of researchers has developed a novel model to describe how knitted fabrics deform, challenging conventional understanding of their resting shape. The study builds on previous work, focusing on the intricate interplay between yarn properties and contact dynamics within a simple knit structure.
The initial research, conducted in 2018, established a foundational mathematical framework by identifying key factors such as yarn bendiness, length, and stitch crossing points, enabling scientists to understand basic knit deformation. This earlier work was inspired by observing the resilient nature of knitted baby booties.
Expanding on this, a recent investigation led by Samuel Poincloux, along with colleagues Jérôme Crassous and Audrey Steinberger, delved into the challenge of predicting the resting shape of knitted fabric. This problem, rooted in a 1959 research paper, has been difficult to address due to the complexity arising from the many contact zones within the textile.
To simplify the modeling, the team focused on a Jersey stitch knit, also known as stockinette, composed of interconnected loops. Employing both experiments and numerical simulations using discrete elastic rods with dry contact, researchers analyzed how frictional forces affect the fabric's shape when no external stresses were applied.
The study revealed that frictional forces within the fabric play a key role in stabilization, and there isn't just one final resting shape. The fabric's shape is determined by its history of folding, stretching and handling. "Knitted fabrics do not have a unique shape when no forces are applied, contrary to the relatively common belief in textile literature," explains Crassous. The findings, published in Physical Review Letters, shed new light on the mechanics governing the behavior of everyday knitted materials.
