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The dynamic response of a ballooning yarn: theory and experiment

Rotating yarn loops, which are called yarn balloons in the textile industry, play an important role in establishing yarn tension in textile yarn manufacturing processes such as ring–spinning, and two–for–one twisting. Recent theoretical work has brought the computational simulation of these processes to a high degree of refinement. In this paper, a simple experimental system consisting of a loop of yarn rotating about a fixed axis, without twist insertion, is described. This system exhibits a rich variety of bifurcation behaviours as the length of yarn in the loop is varied. It is shown that the theoretical bifurcation curves (which plot guide–eye tension vs the unstretched yarn length in the rotating loop) can be fitted to the experimentally obtained curves by an appropriate choice for the value of the air–drag parameter. For the almost inextensible yarns considered here the value of the elasticity parameter has only a very slight affect on the theoretical results. In particular, it is shown that the ‘fluttering’ oscillations of the experimental balloons, corresponding to certain sections of the experimental bifurcation curve can be identified with the limit–cycle behaviour of the theoretical balloons between Hopf bifurcation points on the theoretical bifurcation curve.