Engineering the geometry of novel yarns for flexible, hybrid composites Part I: Multiple breaks

This study reports on the development of a novel form of yarn reinforcement for making super tough, flexible composites. The concept is based on the rupturing of components of the composite yarn many times before totally breaking. The composite yarn structure has a configuration of three main components − helical, straight and sinusoidal. The components are not restricted by the type of raw material, and any type of fibre or blend can be used. Experimentally, the hollow-spindle spinning system was used to make nine variants of this composite yarn. These variants were tested for their tensile behaviour at an extension rate of 250 mm/min. It was found that the core component of two of the nine variants had eight breakages, while the core component of the remaining variants had four to five breakages before the final break of the core component. The main mechanism that allows the core component yarn to break so many times is a locking applied to it by the wrapping yarn during stretching. The gain in strength for these variants was 21–81% in comparison with a typical twistless composite yarn. Flexible composites made of such yarn configurations can find numerous uses in construction, geotextiles, ballistic protective garments, aerospace, automotive and shipping industries.