Effects of Repeated Extension and Recovery on Selected Physical Properties of ISO-301 Stitched Seams

Abstract

In order to examine the mechanisms by which seams age and fail under loads typical of those in use, factors and interactions among factors influencing the change in load required to extend an ISO-301 stitched seam (type ISO 1.01.01) during repeated lon gitudinal extension/recovery cycles at low loads are identified. Fabric type and exten sion limit have the greatest effect on the load required to reach maximum extension of the seam between 0-100 cycles, while fabric type is important over the range 100- 5000 cycles. Variables depending on inclusion of the seam (thread type, linear stitch density) have the most influence during the initial extension. Visual aspects of seam ageing are examined with optical and scanning electron microscopes, and two distinct processes occurring during tensile cycling are identified. Fabric type and thread type are the most important variables affecting the breaking load and breaking extension of cycled seams. Although interactions among variables are not important individually, together they account for 13% of the total variance in breaking extension.