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Oral Poster Presentation

Wavy knits – enabling the production of auxetic materials

Wednesday (07.10.2020)
19:10 - 19:13

The application of weft-knitted structures is well-established in different industrial sectors like automotive, medicine or space. For example, a current research project develops a “fishing net” for space which collects space debris and thus protects i.e. the ISS and satellites. An advantage of knits is near-contour production during the manufacturing because of the versatility of the structuring options. A main characteristic for wavy knits is the directional dependence of the properties because of their structure. If the structure is loaded across the wave direction, the elasticity increases and the total surface expanse due to the unfolding of the structure, what is limited or disabled along the wave direction. The mechanical behaviour of the knitted fabric results from the arrangement of the meshes. A well-defined assembly of the meshes enables the implementation of an auxetic behaviour of the fabric.

This work compares auxetic wavy knits with auxetic pattered sheets. The auxetic structures are manufactured in a knitting machine and a thermoforming machine respectively. As knitting material, a polyester monofilament with a diameter of 0.15 mm and for the patterned sheets a thermoplastic polyurethane is used. The mechanical behaviour of each structure is investigated in tensile tests and the influence of mesh order and the geometry of the pattern of the sheet on deformation and stiffens are evaluated. This paper gives an overview about the comparability between weft-knitted structures and patterned sheets.

Speaker:
Angela Schwarz
Fraunhofer Institute for Chemical Technology ICT
Additional Authors:
  • Daniela Schön
    Fraunhofer Institute for Silicate Research ISC
  • Kevin Moser
    Fraunhofer Institute for Chemical Technology ICT