Dynamic failure of Dyneema SK76 single fibers under biaxial shear/tension

Dyneema SK76 single fibers have been subjected to various known levels of both torsional shear strain and axial tensile stress in efforts to determine the resulting combined loading effects. High rate axial tension experiments were performed on pre-twisted fibers utilizing a miniature tension Kolsky bar and MTS servo-hydraulic system, while the resulting torque generated by fibers loaded to specific degrees of shear strain was determined via implementation of a video-based torque sensing technique. Compilation of the two stress state environments has generated a biaxial failure surface criterion yielding the residual tensile strength of single fibers when subjected to a specific grade of shear stress. Further analysis of fiber surface damage reveals longitudinal surface striation development at elevated levels of shear strain. Propagation of these undulations has been also investigated in order to determine their penetration depth and resulting internal fiber damage.