A generalized FEM model for fiber structural and mechanical performance in fabrication of slender yarn structures

Slender yarn structure made from natural fibers, nano-fibers, carbon nanotubes or other types of fibrous materials is all formed by twisting an assembly of short or long fibers and its performance is significantly influenced by the physical behavior of these fibers in the slender yarn forming region - a small triangle area called spinning triangle. In this paper, a new generalized FEM model of spinning triangle has been developed to theoretically analyze the fiber structural and mechanical performance in fabrication of these slender yarn structures. In this proposed model, a geometrical model of spinning triangle is developed and the initial conditions are formulated together with algorithms for fiber buckling. Compared with the earlier models, some important parameters ignored previously such as the inclined angle of spinning tension and fiber torsional strains are considered. Fiber tensions predicted by the model are in good agreements with earlier models while the predicted torque of slender yarns is generally more close to experimental measurements. In addition, the effect of the parameters neglected previously has also been fully analyzed by using the proposed FEM model.