Analysis and measurements of core and interlayer buckling defects in wound rolls.

摘要

Experiments were conducted using a laboratory-scale web transport system in order to study the formation of defects within wound rolls. Three roll conditions---no defects, starring, and v-buckling---can occur for different combinations of the web's winding tension, core thickness, and roll diameter. Repeatable demarcations between the stable and buckled configurations were identified as functions of tension and roll diameter. The elastic properties of the web and core obtained through measurements are key parameters in determining the state of stress within a roll; those experimentally-determined properties are used to validate the defect models developed in this thesis.;The v-buckling model treats the core as a thin ring subjected to the external pressure generated by the wound-in stresses, and a non-uniform elastic foundation represents core-web contact (or loss thereof). The core's critical buckling pressure and shape are calculated through the model and an iterative numerical technique. Slight geometric imperfections in the core can reduce its ability to resist compressive loads, and critical wavenumbers of such imperfections are shown promote v-buckling deformation.;Addressing the second mode of defects in wound rolls, the starring model considers a group of corrugated layers interior to the roll as multiple rings subjected to radial pressure arising from the wound-in stresses, and to the elastic support of the core and the roll's outer layers. Roll stability and the number of corrugated layers are determined by comparing the critical pressure to the resultant radial stress as calculated from the companion stress model. (Abstract shortened by UMI.).