ISO 3341 Tensile Textile Glass Yarn Test Equipment

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Glass yarn is yarn made from many interwoven glass fibers. This standard defines testing to determine breaking force, breaking strength and lengthening. The breaking force is the maximum force registered (or reached) during a breaking test on the test piece, carried out on a tensile testing machine with constant rate of traverse of the moving element. That constant rate is 200mm/min. The breaking force values given in the tables of glass yarn specifications are only valid when this type of testing machine is used.

The key challenge in testing glass yarn is gripping the material in a way that does not significantly reduce the strength of the material. Almost all grips will cause a stress concentration on glass yarn material because they must squeeze the sample enough to avoid slippage during loading. 2 gripping strategies have proven effective:

  1. The use of capstan bollard grips, where the material is wound around a cylinder with friction and then gripped. This reduces the tensile force at the edge of the grip jaws which encourages the material to break between the capstan cylinders at a force that is very close to the true tensile strength of the specimen material. A problem with capstan grips is that it is hard to determine the true gauge length of the material because some of the material along the capstan cylinder lengthens during the test.
  2. The use of potted tabs at both ends of the glass yarn material. We can recommend PMMA epoxy potting material. Use form that create tabs at both ends of the material. The shape of the tabs should be such that a vice grip can grab them well. The problem with this gripping strategy is the test preparation time is typically at least 24 hours for the epoxy curing time.

Equipment Required

Universal testing machine capable of a constant rate of extension of 200 mm/min +- 20 mm/min. The machine shall be capable of stressing the sample until failure occurs. If the test machine has a pre-tensioning capability, a pre-tension force of 5 mN/tex +- 22.5 mN/tex shall be applied to the specimen. Give our test engineers a call today for help configuring the best test machine and accessories according to your standard.

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