Multibody modeling and its numerical simulation for the unwinding motion of flexible yarn considering twist

要旨

In this paper, a model of yarn considering stretching, bending and twisting motions is constructed. The proposed yarn model is based on rigid multibody dynamics and expresses the dynamical behavior of flexible yarn. The yarn model is made of successive computational units. The computational unit consists of a rigid sphere with mass, a massless cylinder and three sets of springs and dampers for stretching, bending and twisting motions. In the numerical simulation of the unwinding motion of a yarn from bobbin, the computational units located at the ends of a yarn are easily generated or extinguished. The proposed yarn model has the following features: it can easily treat the contact force interacting with walls, and it can reduce the computational cost. In this study, validity of the proposed yarn model is confirmed by comparing the numerical simulation results of unwinding motion of the yarn with the experimental ones. Furthermore, the torsional angles of the yarn rolling on the eyelet guide wall, which is difficult to be measured in experiments, is numerically investigated. Particularly, the occurrence of false twist is observed and explained.

主題