UNE-EN ISO 13934-2:2014

Constant rate of elongation test apparatus (VCA)

• Grip test: Tensile test in which only the central part of the sample is held in the jaws of the testing apparatus.
• Maximum force: The maximum force recorded at the moment the sample breaks during a tensile test carried out under the specified conditions (EN ISO 13934-1).
• Test length: Distance between the two useful clamping points of a test device.

• 5 samples will be taken randomly from a lot or batch.
• A laboratory sample of at least 1m length and full width (from a randomly picked position, but at least 3m from one end of the piece) should be cut from each bulk sample piece. Areas that are wrinkled or have any visible defects should not be included in the sample.
• Two sets of specimens are cut from each laboratory sample, one set in the warp direction and the other in the weft direction (or, as appropriate, in the machine direction and cross direction). machine). Each set must comprise at least five specimens.
• No test piece shall be cut closer than 150 mm from any edge of the laboratory sample. No test piece taken in the warp direction shall contain the same longitudinal threads and no test piece taken in the weft direction shall contain the same courses.
• The width of each sample must be 100 mm + 2 mm and its length must be sufficient to allow a test length of 100 mm.

Apparatus at constant rate of elongation (VCA)

• The apparatus must be able to operate at a constant rate of elongation of 50 mm/min, with an accuracy of ± 10%
• The apparatus must be capable of operating with a test length of 100 mm ±  1 mm, or, by agreement, 75 mm ± 1 mm.
• For the grip test, the dimensions of the surface of the tissue clamped in the jaws should be (25 mm ±  1 mm) x (25 mm ±  1 mm). This surface can be obtained by one or other of the methods a) or b) described below and illustrated in Annex C:

o A clamp (25 mm) x (40 mm minimum, preferably 50 mm), positioned so that its widest side is perpendicular to the force application axis. A second jaw of the same dimensions is placed perpendicular to the first, so that its widest side is parallel to the axis of force application.

o A clamp (25 mm) x (40 mm minimum, preferably 50 mm), positioned so that its widest side is perpendicular to the line of application of force; a second jaw of 25 mm x 25 mm.

The maximum force is to be recorded in Newtons. The test is carried out on at least five specimens from each direction of the fabric.

All test results in which the specimen breaks less than 5 mm from the clamping line of the clamps are recorded, considering the result as breakage in the clamps. After five trials, the results obtained are examined. If one of the jaw break results is higher than the lowest “normal” break result, it can be taken into account. If one of the jaw break results is less than the lowest “normal” break result, it should be rejected and further tests made in order to obtain five “normal” breaks.

If all results are jaw breaks or if it is not possible to obtain five “normal” breaks, the individual results should be recorded without the coefficient of variation or confidence limit.

For wet tests, the specimen is immersed for one hour in class 3 water, in accordance with ISO 3696, at a temperature of 20ºC ±2ºC.

Calculate the arithmetic mean of the maximum force, in Newtons, for each direction tested. The results are rounded for values:

< 100 N                                   up to the nearest 1 N;

³ 100 N hasta < 1000 N          up to the nearest 10 N;

³ 1000 N                                 up to the nearest 100 N;

1. The test report must include the following information:
2. The reference to this part of ISO 13934-2 and the date of the test
3. Identification of the sample assay and method of sampling, if requested
4. The state of the specimens (conditioned or wet)
5. The number of specimens tested, including the number of rejected tests with the reasons for the rejections
6. The test length used if it differs from 100 mm.
7. Any deviation from the described operative procedure
8. The arithmetic mean of the maximum force, in newtons.
9. If necessary, the coefficient of variation of the mean value, in percent.
10. If necessary, the 95% confidence limits of the mean value, in newtons.