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Fabric Tensile Properties Testing ISO 13934: Complete Guide

Testing the tensile properties of fabrics of ISO 13934 is divided into two parts: determination of maximum force and elongation at maximum force using the strip method and determination of maximum force using the grab method, the most complete guide to this standard will be given here.

 ISO 13934-1 Textile – Tensile properties of fabrics – Part 1:

Determination of maximum force and elongation at maximum force using the strip method

Scope, principles, terms, and definition

ISO 13934-1 uses the strip method to test the maximum force and elongation at maximum force of fabric, using a constant-rate-of-extension (CRE) tester, fabric specimens of specified dimensions are stretched at a constant elongation rate until breakage. Record maximum force and elongation at maximum force, and if required, record the force at rupture and elongation at rupture, including tests in both equilibrium and wet states in a standard atmosphere for testing.

This standard applies to woven fabrics, including elastic woven fabrics, but also to fabrics produced by other technologies, usually not applicable to geotextiles, nonwovens, coated fabrics, glass fiber fabrics, and carbon fiber and polyolefin flat wire fabrics.

1 Constant-rate-of-extension tester: During the whole test, one end of the gripper holding the specimen is fixed, and the other end moves at a constant speed so that the elongation of the specimen is proportional to the time.
2 Strip test: tensile test in which the full width of the test specimen is gripped in the jaws of the testing machine.
3 gauge length: the distance between the two effective clamping points of the test device. Clamp the white paper with copy paper to produce clamping pattern on the paper, so as to check the effective clamping point/line of the jaws.
4 Initial length: The length of the specimen between two effective clamping points on the test device under the specified pretension.
5 Pretension: The force applied to the specimen before the test, pretension is used to determine the initial length of the specimen.
6 Maximum force: The maximum force recorded when the specimen is pulled off during the tensile test under the specified conditions, i.e., the fracture strength.
7 Force at rupture: force recorded at the point of rupture of a test specimen during a tensile test.
8 Extension: increase in length of a test specimen produced by a force.
9 Elongation: ration of the extension of a test specimen to its initial length.
10 Elongation at maximum force: elongation of a test specimen produced by the maximum force.
11 Elongation at rupture: elongation of a test specimen corresponding to the force at rupture.

5~11 as shown in the figure below

force-elongation curve

Requirements of test apparatus and test environment

1 Constant-rate-of-extension testing machine

It should have a device to indicate or record the force applied to the specimen and the corresponding elongation of the specimen, and the accuracy of the instrument should be in accordance with the requirements level 1 of ISO 7500. At any point within the full range of the instrument, the error of indicating or recording the maximum force should not exceed ±1%, and the error of indicating or recording the length of jaws should not exceed ±1mm, if the tensile tester of level 2 accuracy in ISO 7500 is used, it should be stated in the test report.

If a data acquisition circuit and software are used to obtain the data of force and elongation, the frequency of data acquisition should be not less than 8 times/sec. The instrument should be able to set the tensile speed of 20mm/min and 100mm/min with an accuracy of ±10%. The instrument should be able to set the gauge length of 100mm and 200mm with an accuracy of ±1mm.

The center point of the two jaws should be in the tension axis, the front jaw line of the clamp should be perpendicular to the tension line, the clamping surface should be in the same plane, the jaw surface should be able to hold the specimen without making it slip, not shear or damage the specimen. The jaw surface should be flat and smooth, when using flat jaws, specimens produce specimen slippage, it can use corrugated surface or groove surface jaws, can also be attached to the flat or corrugated surface other auxiliary materials (including paper, leather, plastic, or rubber) to improve the clamping force of the specimen, the width of the jaw surface of at least 60mm, and not less than the width of the specimen.

2 Apparatus, for cutting test specimens and for fraying them to obtain the required width. Apparatus, in which test specimens can be immersed in water preparatory to wet testing. Grade 3 water, in accordance with ISO 3696 for wetting test specimen, and nonionic wetting agent.

3 Atmosphere for conditioning and testing

The atmosphere for preconditioning, conditioning, and testing shall be as specified in ISO 139. The temperature of (20±2)℃, the humidity of (65±4)%, it is recommended that the specimen in the relaxed state at least 24H conditioning, for the test of wet state, it does not require preconditioning and conditioning.

Sampling and specimen preparation

1 Sampling

Randomly cut a full width of at least 1m from each pile of the batch as a laboratory sample. Ensure that the sample is free of creases and obvious blemishes.

2 Specimen preparation

Cut a group of specimens from each sample in warp and weft direction respectively, each group should include at least 5 specimens, if there is a higher precision requirement, the number of specimens should be increased. The specimens should be representative, avoiding wrinkle and wrinkle at least 150mm from the edge of the cloth. The warp specimen group should not be sampled on the same warp yarn and the weft specimen group should not be sampled on the same weft yarn.

The effective width of each specimen should be (50±0.5)mm, its length should be able to meet the gauge length of 200mm, if the elongation at maximum force of the specimen more than 75%, the gauge length can be 100mm. According to the relevant agreement, the specimen can also be used other widths, but should be stated in the experimental report.

The length direction of the specimen should be parallel to the warp or weft direction of the fabric, and its width shall be determined according to the width with fringes. An approximately equal number of yarns are removed from both sides of the specimen along the length until the effective width of the specimen is (50±0.5)mm. During the test, the width of the burlap should be such that the yarn does not come out of the fringes.

For the general woven fabric, the fringes is about 5mm or 15yarn width is more appropriate; for the tighter woven fabric, narrower fringes can be, for the more loose woven fabric, the fringes is about 10mm.

For fabrics containing only a few yarns per centimeter, the width of the specimen should be as close as possible to the width specified in the specimen after fraying. Count the number of yarns in the whole width of the specimen, if ≥20, the number of yarns in the specimen should be the same after fraying; if <20, the specimen should contain yarns at least 20. If the specimen width is not (50±0.5)mm, the specimen width and the number of yarns should be stated in the specimen report.

For the fabric that can not be frayed, the specimen should be sheared in parallel with a width of 50mm along the fabric longitudinal or transverse. Some only tear to determine the yarn direction of the woven fabric, its specimens should not be used to shear method to achieve the required width.

3 Wet specimen preparation

If the maximum force of the wet fabric needs to be measured at the same time, the length of the cut specimen should be at least twice as long as that of the dry maximum force specimen. Number the two ends of each specimen, fraying to the specified width and cut them into two pieces along the transverse direction, one for determining the dry maximum force and the other for determining the wet maximum force.

Make sure that the length direction of each pair of specimens contains the same yarn. According to experience, it is estimated that the shrinkage of the fabric after soaking, the length of the specimen for determining the wet maximum force should be longer than the specimen for determining the dry maximum force. Wetting test specimens should be placed in the temperature (20±2)℃ of tertiary water wetting more than 1H according ISO 3696, it can also be used per liter containing no more than 1g of non-ionic wetting agent aqueous solution instead of tertiary water. For testing in tropical areas, the temperature can be set according to ISO 139.

Test procedure

1 Set the gauge length

For fabrics with elongation ≤75% at maximum force, the gauge length is (200±1)mm. for fabrics with elongation >75% at maximum force, the gauge length is (100±1)mm.

2 Rate of extension or elongation

Set the rate of extension or elongation of the tensile tester according to the elongation at maximum force of the fabric in the table below.

gauge length(mm) Elongation at maximum force of fabric(%) Rate of

elongation(%/min)

Rate of

extension(mm/min)

200 <8 10 20
200 8 to 75 50 100
100 >75 100 100

3 Specimen mounted

The test specimen can be mounted with pretension or with “slack mounted”, i.e. hanging freely under its own mass. Using slack mounted, one end of the specimen is clamped in the center of the upper jaw, and the other end is draped flat in the lower jaw by its own mass and parallel to the direction of tensile force to ensure that the center line of tension passes through the midpoint of the jaw, while closing the lower jaw.

The initial length of the elongation at maximum force is the sum of the gauge length and the elongation of the specimen up to the specified pretension. The extension of the specimen is measured from the point of the force-extension curve that corresponds to the pretensioning force. If an electronic device is used to record elongation, ensure that the correct initial length is used  for calculation of elongation.

Mounted with pretension, apply the appropriate pretension. Elastic fabric using 0.5N; non-elastic fabric, according to the mass per unit area of the specimen using the required pretension.

mass per unit area pretension
≤200g/m2 2N
>200g/m2 to 500g/m2 5N
>500g/m2 10N

4 Tessile tester operation

Start the tensile tester so that the moveable clamp moves and stretches the specimen until it rupture. Record maximum force, extension at maximum force or elongation at maximum force, and if required, record force at rupture, extension at rupture and elongation at rupture. Test at least 5 specimens in each direction, record the extension or the elongation at least to the nearest.

For elongation <8% 0.4mm or 0.2%
For elongation 8% to <75% 1mm or 0.5%
For elongation >75% 2mm or 1%

If the slip of the specimen along the jaw line is asymmetrical or the slip is greater than 2mm, discard the test result.

5 Test on wet specimen

Remove the specimen from the aqueous solution, placed on absorbent paper to absorb excess water, and immediately tested according to the above test procedure. For wet specimen, apply half of the pretension specified in the dry specimens.

6 Calculation and expression of results

Calculate the arithmetic mean of the maximum force and, if required, the arithmetic mean of the force at rupture, in newtons, for each direction tested. The calculation result is modified as follows.

<100N to the nearest 1N
100N to <1000N to the nearest 10N
≥1000N to the nearest 100N

Calculate the average value of elongation at maximum force in the warp and weft directions respectively, and if necessary, calculate the average value of elongation at rupture, and the calculation results are modified as follows.

0.2% for elongations <8%
0.5% for elongations 8% to <75%
1% for elongations >75%

If required, calculate the coefficient of variation to the nearest 0.1% and the 95% confidence limits of the relevant properties tested, rounded to the same precision as the mean values.

 ISO 13934-2 Textile – Tensile properties of fabrics – Part 2:

Determination of maximum force using the grab method

Scope, principles, terms and definition

Grab method test is a tensile test in which the central part of the width direction of the specimen is held by a clamp. The scope of application, test apparatus, gauge length, maximum force are the same as ISO 13934-1 strip method.

Apparatus and atmosphere for conditioning and testing

The constant-rate-of-extension tester has the same accuracy requirements as the strip method ISO 13934-1, but the equipment parameters requirements are different, the extension speed is 50mm/min (accuracy ±10%), the gauge length is 100mm or 75mm (accuracy ±1mm).

The requirements of the clamping device are the same as strip method ISO 13934-1, but the size requirements of the clamping device are different. The size is (25±1) mm * (25±1) mm.

Apparatus, for cutting test specimens and for fraying them to obtain the required width. Apparatus, in which test specimens can be immersed in water preparatory to wet testing. Grade 3 water, in accordance with ISO 3696 for wetting test specimen, and nonionic wetting agent.

The atmosphere for preconditioning, conditioning and testing shall be as specified in ISO 139. The temperature of (20±2)℃, humidity of (65±4)%, it is recommended that the specimen in the relaxed state at least 24H conditioning, for the test of wet state, it is does not require preconditioning and conditioning.

Sampling and specimen preparation

1 Sampling

Randomly cut a full width of at least 1m from each pile of the batch as a laboratory sample. Ensure that the sample is free of creases and obvious blemishes.

2 Specimen preparation

Cut a group of specimens from each sample in warp and weft direction respectively, each group should include at least 5 specimens, if there is a higher precision requirement, the number of specimens should be increased. The specimens should be representative, avoiding wrinkle and wrinkle at least 150mm from the edge of the cloth. The warp specimen group should not be sampled on the same warp yarn and the weft specimen group should not be sampled on the same weft yarn.

The effective width of each specimen should be (100±2)mm, its length should be able to meet the gauge length of 100mm. A marker line is drawn on each specimen along the yarn parallel to the length of the specimen, which is 38 mm from the long side of the specimen and runs through the entire length of the specimen.

Test procedure

1 Set the gauge length of the tensile tester to 100mm or the gauge length can be 75mm as agreed by the relevant parties with accuracy ±1mm.

2 Set the extension speed of the tensile tester to 50mm/min.

3 Clamp the specimen. Ensure that the longitudinal centerline of the specimen passes through the centerline of the clamp and is perpendicular to the jaw line, so that the mark line on the specimen is aligned with one side of the clamp. After clamping the upper jaw, the other end is draped flat in the lower jaw by its own mass and close the lower clamp.

4 Start the tensile tester, stretch the specimen to rupture, record the maximum force, each direction at least 5 test specimens.

Wet specimen test: Remove the specimen from the aqueous solution, placed on absorbent paper to absorb excess water, and immediately tested according to the above test procedure.

The calculation results are modified in the same way as ISO 13934-1.

The above is a complete guide to the ISO 13934 test standard, hope it can help you.

 

 

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