Development of a Constitutive Theory for Short-fiber Yarns Part IV: The Mechanics of Blended Fibrous Structures.

This paper presents a thorough study on the prediction of the elastic-material constants ratios of blended short-fiber yarns, based on the theory developed by the author for yarns of a single fiber type by considering the structures as transversely isotropic and combined with the techniques used in dealing with hybrid composite materials. The mean tensile strengths of the blended staple-fiber yarns are also predicted, with the exclusion of the statistical and hybrid effects, which will be dealt with in a separate paper because of their extreme complexity. The so-called minimum blend ratio, below which the mean yarn strength will not follow the rule of mixtures, and the critical blend ratio, below which the mean yarn strength will be weakened rather than strengthened owing to the addition of the reinforcing fibers, are calculated, and the variables involved are discussed. Finally, the effects of the breaking strains between the blending-fiber types on the yarn properties are investigated. All results are schematically illustrated and the necessary parametric studies are provided. [ABSTRACT FROM AUTHOR]