*Invited* Thermomechanical Behavior of NiTi Textiles and Elastomeric Composites

Flat, cylindrical or complex-shaped textile structures can be made using textile processing of thin Nitinol wires. Nitinol textiles inherit functional properties of shape memory alloys such as superelasticity or shape memory effect and transform them into 2D or 3D. Constitutive behavior of textile structures (strongly anisotropic) can be tailored through adjusting internal textile architecture and functional properties of the NiTi wires by heat treatment. On top of that, functional composites may be engineered by embedding NiTi textiles into compliant elastomeric matrices. SMA textiles and SMA textile composites thus represent very interesting objects for structural design and modeling of smart materials. Provided that their thermomechanical behavior is well understood, they may find applications in many fields for example as highly stretchable superelastic NiTi textiles, active NiTi textile membranes, large stroke R-phase NiTi textile actuators or NiTi elastomeric composites with tissue-like constitutive behavior.

In this work, we are going to report on thermomechanical properties of NiTi textiles manufactured by weft knitting and weaving and NiTi textile elastomer matrix composites. A complete manufacture route is described showing the possibilities to manipulate the internal morphology of NiTi textiles through shape setting and textile processing parameters. Methods for multiaxial thermomechanical testing of NiTi textiles and composites will be introduced and experimental results will be given. Special attention will paid to the effect of the internal architecture of NiTi textiles on their macroscopic behavior. Particularly, the conditions upon which martensitic transformations and reorientation processes are activated in NiTi textiles and elastomeric composites as well as interactions between elastomeric matrices and NiTi textiles will be analyzed.