Behavior of Pleated Strips of Wool Fabric in an Extensometer

Abstract

Certain aspects of the elastico-mechanical behavior of pleated strips of worsted wool fabric have been examined using a specially constructed extensometer. On subjecting the pleat specimens to cycles of extension and retraction, the load-vs.-extension charac teristic settled down to a repeatable hysteresis loop after about eight cycles. The loop area being relatively small, a study was made of an ''ecluivalent hysteresis-free" mean characteristic. This was found to indicate behavior which to the first order was that expected of a flat strip of linear-Hookean material having a fixed "pleat angle" at the midpoint. It should be possible to develop a relatively simple apparatus to examine pleat sharpness using the technique described here of taking successive superimposed flash photographs while extending the pleat specimen.