Wound roll stresses from displacement measurements

Abstract

Previous wound roll models required a known Wound-In-Stress boundary condition that is easily obtainable only for the restrictive case of pure center winding with measured incoming web tension and caliper. A new boundary condition and model were defined that allows wound roll stresses to be predicted for any winding case from roll diameter and web caliper measurements. These measurements are made during winding using an instrument similar to a density analyzer but extended to include web caliper. These measurements as well as material properties are input into winding models which have been extended to also calculate displacements. The net result is a measurement technique at least an order of magnitude more sensitive that previous methods, as well as fundamental outputs of radial and tangential stresses and strains at any point in the roll and at any time during the winding process.