Specific stress (breaking force), elongation at break, and work of rupture are the rupture characteristics of yarn and fiber, each of which can be decisive, important, and effective based on the final application of the yarn and fiber.

Examination of breaking force and elongation at break for filament yarns

For example, in the preparation of a rope that is used to lift heavy objects, force or tension should be considered when the yarn is torn, while for warp yarns in fabric weaving, the elongation at break should be considered. Or the climbing rope should be made of fibers that have a high work of rupture and it is not necessary that the tension to rupture be high.

Video of the steps of performing this test in the laboratory of Sirang Co.

Introduction of the constant rate of elongation (CRE) tester

CRE tester can be used to determine the breaking force (specific stress) and elongation at break of the yarn according to the international standards ASTM D2256 and ISO 2062 or the national standard of Iran ISIRI 29. The function of this device is such that one end of the yarn is placed in a fixed clamp and the other end is placed in a clamp that moves at a constant speed. This device is fully automatic and is equipped with a system for displaying and recording the breaking force and elongation at break. It is also able to draw a stress/strain diagram that can be used to analyze the elastic and plastic behavior of yarn.

Among the parameters related to this machine that must be adjusted before the test are the pretension, the initial length of the test sample, the speed of the movable clamp, and finally the linear density, which is adjusted according to the relevant standards.

For example, to measure the parameters of breaking force and elongation at break and work of rupture of 100% polyester FDY yarn with a certain density, gauge length of 500 mm, movable clamp speed of 500 mm/min, and pretension of 0.05 cN/dtex are set.

It is noteworthy that according to the national standard of Iran, the strength of FDY, POY, and dope-dyed DTY yarn is at least 4, 2, and 3.5 g/denier, respectively.

The allowable range of FDY, POY, and DTY yarn elongation at break is 18-48%, 100-170%, and 17-30%, respectively.

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