Dynamic control of active textiles: The integration of Nickel-Titanium Shape Memory Alloys and the manipulation of woven structures.
Tony Anson (external)
The creation of controlled patterns of movement in woven textiles, through the integration of wire-form, nickel titanium (Ni/Ti), shape memory alloys (SMA), offers the potential to generate unique properties in this bi-material composite. The combination of two materials, one of which can be modified in regards to its stiffness and elastic behaviour, gives further latitude, for the textile designer to adapt, a combination of functional and aesthetic properties in constructed textiles. Little work has been done to understand the relationship and behaviour of an SMA wire integrated into a woven structure. The interaction between the SMA wire and the host structure is critical since most of the proposed applications require a transfer of force from the wire to the woven structure.
This thesis investigates how the woven structure and supporting yarn of a flexible material could be used to facilitate or impede the movement and control of an integrated NiTi wire. Composite samples of different weave structures, supporting yarn, NiTi cross sections and finishes were successfully produced. Mechanical properties of the NiTi integration were investigated through a series of bend and tensile tests using a basic mechanical mass loading and resultant extraction of the integrated NiTi from the woven materials. This was supplemented by computer controlled tensile / compression testing machines. Subjective evaluations of, visual and tactile properties were also carried out, together with comparative topography and morphology investigations using a scanning electron microscopy system. Investigations regarding composition, of the shape memory alloy were conducted at the same time, using energy dispersive X-ray analysis.
The tabulation of the results of this research, will support decision making in this emerging design field, and act as a foundation, for the development of the technology. Examples of actively controlled textile applications, such as integral textile fastenings and adaptive 3D skins are described and discussed.