Influence of Bending Intensity on Stiffness of Textile Threads

A study was made of the bending stiffness of threads differing fundamentally in structure and fiber composition, such as textured threads, high-bulk yarn, mixed staple yarn, cotton yarn, and medical-purpose monofilaments and stitching threads. Bending diagrams were obtained at six levels of sample flexure, which was determined by the slope angle of the tangent to the sample edge relative to the vertical. It was found that the stiffness of textile threads is a variable quantity that increases with increase of sample curvature. The influence of curvature on the thread stiffness increases with increase of the degree of orientation of the macrostructure of the thread along its axis.