Knitted Textiles made from Nickel-Titanium (NiTi) shape memory alloy wires are a new structural element with enhanced properties for a variety of applications. Potential advantages of this structural form include enhanced bending flexibility, tailorable in-plane, and through-thickness mechanical performance, and energy absorption and damping. Inspection of the knit pattern reveals a repeating cell structure of interlocking loops. Because of this repeating structure, knits can be evaluated as cellular structures that leverage their loop-based architecture for mechanical robustness and flexibility. The flexibility and robustness of the structure can be further enhanced by manufacturing with superelastic NiTi. The stiffness of superelastic NiTi, however, makes traditional knit manufacturing techniques inadequate, so knit manufacturing in this research is aided by shape setting the superelastic wire to a predefined pattern mimicking the natural curve of a strand within a knit fabric. This predefined shape-set geometry determines the outcome of the knit’s mechanical performance and tunes the mechanical properties. In this research, the impact of the shape setting process on the material itself is explored through axial loading tests to quantify the effect that heat treatment has on a knit sample. A means of continuously shape setting and feeding the wire into traditional knitting machines is described. These processes lend themselves to mass production and build upon previous textile manufacturing technologies. This research also proposes an empirical exploration of superelastic NiTi knit mechanical performance and several new techniques for manufacturing such knits with adjustable knit parameters. Displacement-controlled axial loading tests in the vertical (wale) direction determined the recoverability of each knit sample in the research and were iteratively increased until failure resulted. Knit samples showed recoverable axial strains of 65–140%, which could be moderately altered based on knit pattern and loop parameters. Furthermore, this research demonstrates that improving the density of the knit increases the stiffness of the knit without any loss in recoverable strains. These results highlight the potential of this unique structural architecture that could be used to design fabrics with adjustable mechanical properties, expanding the design space for aerospace structures, medical devices, and consumer products.
Skip Nav Destination
ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems
September 10–12, 2018
San Antonio, Texas, USA
Conference Sponsors:
- Aerospace Division
ISBN:
978-0-7918-5195-1
PROCEEDINGS PAPER
Manufacture of Ultra-Dense Knitted Superelastic Structures
Henry Koon,
Henry Koon
University of Minnesota, Minneapolis, MN
Search for other works by this author on:
Jack Laven,
Jack Laven
University of Minnesota, Minneapolis, MN
Search for other works by this author on:
Julianna Abel
Julianna Abel
University of Minnesota, Minneapolis, MN
Search for other works by this author on:
Henry Koon
University of Minnesota, Minneapolis, MN
Jack Laven
University of Minnesota, Minneapolis, MN
Julianna Abel
University of Minnesota, Minneapolis, MN
Paper No:
SMASIS2018-8225, V002T08A013; 9 pages
Published Online:
November 14, 2018
Citation
Koon, H, Laven, J, & Abel, J. "Manufacture of Ultra-Dense Knitted Superelastic Structures." Proceedings of the ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. Volume 2: Mechanics and Behavior of Active Materials; Structural Health Monitoring; Bioinspired Smart Materials and Systems; Energy Harvesting; Emerging Technologies. San Antonio, Texas, USA. September 10–12, 2018. V002T08A013. ASME. https://doi.org/10.1115/SMASIS2018-8225
Download citation file:
25
Views
Related Proceedings Papers
Design and Analysis of SMA Woven Fabric
SMASIS2018
Related Articles
Seismic Vibration Control Using Superelastic Shape Memory Alloys
J. Eng. Mater. Technol (July,2006)
Shape Memory Alloy Based Morphing Aerostructures
J. Mech. Des (November,2010)
Shape Memory Alloy Expandable Pedicle Screw to Enhance Fixation in Osteoporotic Bone: Primary Design and Finite Element Simulation
J. Med. Devices (September,2012)
Related Chapters
Introduction and Definitions
Handbook on Stiffness & Damping in Mechanical Design
Subsection NG—Core Support Structures
Companion Guide to the ASME Boiler & Pressure Vessel Codes, Volume 1 Sixth Edition
Getting Ready for Production
Total Quality Development: A Step by Step Guide to World Class Concurrent Engineering