Effects of Non-Uniformity on Trough Instability in Nonwovens
Abstract
A web is defined as a material whose length is very large compared to its width and the width is much greater than the thickness. Web material includes paper, fabric, metal, plastic film and composites. Nonwoven fabric is a fabric-like material made from long fibers that are bonded together by chemical, mechanical, heat or solvent treatment. In nonwovens, there exists thickness and modulus variations in many different regions over a length of web. In our research, we study on SMS nonwoven web. SMS refers to Spunbond-Meltblown-Spunbond which is a tri-laminate nonwoven web. Generally, web instability occurs between the rollers in the form of troughs and on the rollers in the form of wrinkles. The direction in which the web travels is called the Machine Direction (MD) and the direction perpendicular to the MD is called the Cross-Machine Direction (CMD). These instabilities can affect the web quality. Nonwovens have thickness and modulus variation in different regions in a span of web. Nonwovens are much more prone to the web instability than the uniform web. Understanding the effects of non-uniformity is needed to solve trough/wrinkling problems in nonwovens. To understand the localized instability problems associated with nonwovens, two major challenges remain: (1) how to characterize the non-uniformity of nonwovens and how to relate the non-uniformity to the thickness and material property variations, and (2) how to implement the thickness and modulus variations in FEA to simulate troughs if the information in the previous step is obtained. This research is designed to answer these questions. Here, the thickness is correlated with the modulus (MD and CD directions). This is achieved by performing experiments to characterize the thickness distribution in nonwovens, characterizing effective material properties for web samples of different thickness, and adopt finite element analysis by considering material as isotropic and orthotropic to find out how the variation in material properties and thickness is related to trough instability, and then compare the FEA predictions to experimental results on critical troughing load and trough profiles.
Collections
- OSU Theses [15752]