Strengths of twisted blend fibrous structures: Theoretical prediction of the hybrid effects

Hybrid structures have been applied in many areas such as textiles and composites. However, the mechanisms giving rise to the advantages associated with fiber blending, presumably due to the interactions between constituents of different types, are still poorly understood. This work is an attempt to look into the internal interactions through theoretical analysis. A twisted structure (yarn) of two distinct fiber types with statistically distributed strengths is studied. It has been established in yarns of the single fiber type that the interaction via friction between fibers will lead to a substantial increase of fiber effectiveness, and consequently the yarn strength. Incorporating this concept into the present hybrid case makes it possible to more accurately predict the strength and its distribution for the blended yarn. Moreover, it is revealed in this study that the interaction between fibers prior to the initiation of yarn failure may be the most important factor which causes the so-called hybrid effects. Predictions of the hybrid effect are provided and the influences of relevant factors are discussed in this paper. Although the present work is targeted at hybrid yarn structures, the conclusions drawn herein are in principle applicable to hybrid fiber composites as well.