Failure of Dyneema® SK76 single fiber under multiaxial transverse loading

This article investigates the failure of ultra-high molecular weight polyethylene Dyneema® SK76 single fibers widely used in protective armor applications. Indenter geometry and the associated stress concentration are known to have a significant effect on the average axial tensile failure strain of Dyneema® SK76 fibers subjected to quasi-static transverse loading experiments by three indenter geometries. In this study, a 3D finite element model is developed to predict the degree of multiaxial loading at the location of fiber failure in these experiments. A failure criterion based on maximum axial tensile strain considering the statistical strength distribution and multiaxial loading (transverse compression and transverse shear) induced degradation effects is applied to predict the fiber failure. The influence of transverse compression on the tensile strength of single fibers is experimentally determined. The average failure strains predicted by the model are found to agree well with the experimental results indicating fiber failure may be initiated based on a gage length dependent maximum axial tensile strain in the fiber.