The Stress-Strain Relation in Textile Fibers

Stress-strain relations for eight common textile fibers are given (four rayons, silk, wool, cotton and ramie) under known humidity conditions. The method has two novel features: (1) In each experiment the section area was determined on the specific fiber under test, (2) the elongations were made in steps, with a relaxation interval of 30 seconds between stress observations, rather than at a constant rate which is the usual practice. The rayons exhibit an accurately linear initial curve from which Young's modulus can be determined, followed by a yield point and a long region of plastic flow. The curves for cotton and ramie are linear with no plastic yield in the range examined. In silk and wool there is no proportionality between stress and strain. Cellulose acetate exhibits the phenomena of ``cold working'' and marked increase of total and elastic energy with falling relative humidity. The application of Maxwell's relaxation equation is examined.