A Mechanical Model Analysis of Crepe Puckering.

Abstract

The formation of pucker in a crepe fabric is analyzed as a post-buckling phenomenon which is induced by self-untwisting torque in the constituent yarns over-twisted. The potential energy of the fabric after buckling is composed of three terms, two correspond to the bend and torsion of yarns and the third to the shear deformation of the fabric, where the detwisting torque of yarn is treated equivalently as the pre-loaded or residual torsion. The equilibrium shape of the fabric is determined by the conditions minimizing the potential. The analysis can estimate the critical level which the residual torsion should exceed for the post-buckling state to exist. The parameters which characterize the equilibrium pucker are expressed as functions of the residual torsion relative to the critical value. The results are also compared with experimental information available.