Development of multi-material hybrid yarns consisting of steel, glass and polypropylene filaments for fiber hybrid composites

With the increased use of fiber-reinforced composites (FRPs), the design of a new generation of composite structures with high stiffness and a ductile material behavior is required to cope with complex load scenarios and high damage tolerances. This can be achieved, in particular, by a combination of conventional FRPs, which possess high stiffness and strength, with metallic materials characterized by their high ductility and associated higher energy absorption capacity. Currently, there are no solutions for the hybridization of high-performance filament yarns, metal filament yarns or thermoplastic filament yarns at the micro level. Therefore, the aim of this paper is the hybridization of multi-fiber components intermixed at the micro scale. For this purpose, three hybridization processes were investigated. They are conventional air-jet technology, air-jet technology based on a modified air nozzle and an additional pre-spreading device and a process based on a newly developed multi-level-intermixing device. The effect of different processing parameters, such as air pressure, air nozzle and type of manufacturing, on the tensile properties, appearance and damage of multi-material hybrid yarn was analyzed. The results show that the developed multi-material hybrid yarns have high potential for use in composites with high requirements for crash and impact properties.