A Study on the Bending Properties of Warp-knit Fabrics

Part 1 : Theory

Abstract

A theoretical analysis is given of the bending behavior of warp knit fabrics of two -bar tricot, and a method for making a prediction of the elastic component of the bending property is developed in the case when the radius of curvature is large.
The values required for calculation are the bending and torsional properties of the constituent yarns and the structural constants of the fabric.
In this analysis, the following are assumed : (1) a unit structure has three arcs of front -bar yarn and the same number of arcs of back-bar yarn, (2) the crossover region in unit structure is not deformed, (3) the deformation of an arc is, small and prefectly elastic, (4) no frictional restraint exists, (5) curling couple is zero. A theoretical expression is derived from the resistances to bend these arcs out of its plane of initial curvature, and to twist some part of the loop.
As a course-way bending and a wale=way bending differ in mechanism and also the behavior is markedly asymmetry, its differences are examined in details . Finally, some examples of the calculation are shown to account for its characteristics.