Prediction of Amplitude and Wavelength of Troughs on Polyethylene Webs

Abstract

Out-of-plane deformations occur in free spans of webs, which may be composed from polymers, during their transportation through process machinery. These troughs may become wrinkles when they transgress a roller. As the amplitudes of these out-of-plane deformations increase the propensity for web wrinkles increase. The goal of this research is to determine if the amplitude and wavelengths of the troughs can be estimated. Closed form expressions for amplitude and wavelength of troughs in case of a stretched web were obtained from the literature. Experiments were conducted to stretch the web and measure the out-of-plane deformation. Simulation of troughs formation was done using ABAQUS Explicit. The out-of-plane deformations from both experiments and simulations were obtained at different strain levels for different specimen lengths. Amplitude and wavelength were inferred from the out-of-plane deformations. These amplitudes and wavelengths were compared with the closed form expressions. From the comparisons it was concluded that the wavelength expression was accurate in predicting the wavelengths of the troughs in the elastic and in the inelastic range of the material. The amplitude expressions given by Cerda or developed by Gotimukul are not accurate in predicting the amplitude of the troughs. However these expressions are aids for overestimating the amplitudes of the troughs.