Finite-amplitude stability and draw resonance in isothermal melt spinning

The spinning of fibers from polymer melts is sometimes limited at high takeup rates by the onset of a flow instability known as “draw resonance,” which is characterized by large amplitude fluctuations in the takeup area and the force. In this work, the onset and growth of the spinning instability is analyzed for an isothermal Newtonian liquid by examining the nonlinear dynamics of the most unstable spatial mode. At draw ratios below the critical value D_R = 20·21 computed from linear theory the system is stable to finite-amplitude perturbations. At higher draw ratios all disturbances approach a stable finite-amplitude oscillation which agrees in period and magnitude with experimental observations of draw resonance.