Increase in Regain during Vacuum-steaming

The importance of lateral pressure in the tension and bending behaviour of yarns and fabrics is discussed. To determine the lateral pressure between fibres, a specific model is considered, that of a filament helically wound around a cylinder. The equations governing the equilibrium of the filament are derived and both account for the helical geometry of the filament and allow for the variation of the helix angle. The filament is assumed to possess both bending and torsional rigidities. The special case of constant helix angle yields expressions for the lateral-force intensity as a function of the tension in the filament, bending and torsional rigidities, bending curvature, and torsion. Specific examples are considered to show the relative contributions of the bending and torsional rigidities to the lateral force