Development of three dimensional woven fabrics with superior mechanical properties by using nitinol and steel wire core hybrid yarns

In this study, it was aimed to produce nitinol and steel wire core hybrid yarns and by using these yarns to develop three dimensional woven fabrics, which can be used as composite preform due to their superior mechanical properties. For this purpose, first, hybrid yarn structures, in which nitinol and steel wires in different diameters were used as a core material, were produced. Then these yarns were used as warp yarns in two different fabric constructions. After production, the fabric was supported and ensured to take a hollow form by placing auxiliary steel bars in two different diameters into the fabric gaps that were created depending on the woven construction. These fabrics with nitinol wire in their structure were also exposed to heat treatments to provide them shape memory and superelasticity properties. Within the scope of this study, yarn and fabric tests were carried out simultaneously to evaluate the mechanical properties of nitinol and steel wire core hybrid yarns and wire reinforced fabrics. Tensile tests were applied to all wire and hybrid yarn samples, and DSC and DMA analyses were conducted for only heat treated nitinol wires. Low velocity impact, tensile and pull-out tests were applied to fabric samples. In order to provide a point of comparison to the data from the mechanical properties of wire reinforced fabrics, reference fabrics with no wire were produced and evaluated by comparing with wire reinforced samples. Results obtained from the study were analyzed with regression analysis by using "backward method" and the parameters such as wire type, wire diameter, fabric gap width for optimum fabric production were determined.