Seam Puckering as a Mechanical Instability Phenomenon

Abstract

Results are presented from a study directed toward establishing quantitative relationships among the important systems parameters involved in the puckering of fabric seams treating the phenomena as a problem in mechanical instability. Using idealized models to simulate the mechanical behavior of a simple seam, the elastic stability problem encountered is that of a compressed member supported on a nonlinear foundation which is discontinuous and depends on the final shape of buckling. An energy method is used to obtain approximate theoretical solutions for the buckling behavior of such a model for the case of a straight edge seam subjected to excessive sewing thread tension. These solutions both identify the important system variables and predict what combinations will produce puckering. An experimental study conducted on simulated seam models to verify the theory shows acceptable agreement with predicted results.