Stress-strain relationships in yarns subjected to rapid impact loading: 1. Equipment, testing procedure, and typical results

Abstract

Equipment is d escribed for elongating yarns by longitudinal impact at velociti es ranging from 10 to 100 mcters p er seco nd . Th e ra te of straining at impact varies from about 100,000 to 500,000 precen t p er minute .A procedure is di scussed for obtaining load-elongat ion curves for loading and for unloadin g of t he specimen and for loading to rupture in a time interval of only a few mi ll iseconds. The res ul ts of a typicalloftding and un loading test are prese nted.

Impact Phenomena in Textiles

“…Modern high-speed stitching, in the commercial manufacture of textile articles of all kinds, subjects the thread to impact velocities which may be equivalent to even greater rates of extension. Stone, Schiefer and Fox [88] mention velocities ranging from 1 to 10 m./sec. being imposed on thread as often as 5,000 times/min.…”

“…These are given gjraphically by the distances between the curves A' and B, wh-,r' is curve' A transposed dow.-ward so that A' dnd B coincide for the Velocities of head and tail, as functions of time after impact of nylon yarn [88]. -63-period up to the instant of impact.…”

“…Typical such curves obtained by Stone Film strip showing motion of head and tail masses following impact, which occurred between frames 2 and 3, with maximum tension between frames 10 and 11 [88]. Fig.…”

“…As noted by Stone, Schiefer and Fox [88], the dimensions of laboratory rooms have limited the maximum velocity attainable with pendulums and falling weights to about 20,000 in./min. .…”

“…-Set up at the National Bureau of Standards is rotating-disk equipment with which can be obtained longitudinal impact velocities far exceeding any that could be obtained with a practical gravity device [88]. The central features of this apparatus are shuwn schematically in Fig.…”