A Maple script that produces a geometrical model for 2-component helical auxetic yarns at arbitrary strain. The user may specify the following parameters:
- Elastic core initial diameter
- Winding diameter
- Thickness of optional coating on winding (dielectric layer)
- Initial pitch (helical length)
- Elastic core Poisson's ratio
- Final strain
- Number of turns
The geometry generator has the following assumptions:
- At 0% strain, the yarns contain an extensible elastic core fibre with an inextensible winding.
- The extensible fibre geometry is entirely defined by the extensible fibre (i.e. the inextensible fibre deforms as it would without the presence of the core).
- The fibres are locally stiff, so that the contact path between both is a line.
The script generates 3D renderings of the fibre geometries, an animation of extension from 0% strain to the requested final strain, and cross-sectional bitmap images that can be used to estimate electrical properties.
Please see the included presentation and paper below (with associated SI) for further details. Please cite if this work is useful to you. This script was used in the following publication:
Cuthbert, T. J., Hannigan, B. C., Shokurov, A., & Menon, C. (2023). HACS: Helical Auxetic Yarn Capacitive Sensors that Go Beyond the Theoretical Sensitivity Limit. Advanced Materials, 35(10). https://doi.org/10.1002/adma.202209321
Below is an example animation of a fibre with parameters (0.2, 2, 0.05, 4, 0.4, 1, 2)
©2023 ETH Zurich, Brett Hannigan; D-HEST; Biomedical and Mobile Health Technology (BMHT) Lab; Carlo Menon