GB/T 7689.5-2013Reinforcements -- Test method for woven fabrics -- Part 5: Determination of glass fibre tensile breaking force and elongation at break (English PDF)

3.1 Initial gauge length

The length of the sample between the jaws at the starting positions of two

fixtures under the specified pretension.

3.2 Breaking force

The maximum load that is applied to the sample when the sample is stretched

to break.

3.3 Elongation; extension

The length increment of the sample when it is stretched; it is usually expressed

in the percentage of the original length.

7.1 Size

7.1.1 Type-I sample

The length of the sample shall be 350 mm, so that the effective length of the

sample is 200 mm ± 2 mm. The width of the sample, excluding the burrs (the

split portion of the sample) shall be 50 mm, see 7.2.7.

7.1.2 Type-II sample

The length of the sample shall be 250 mm, so that the effective length of the

sample is 100 mm ± 1 mm. The width of the sample, excluding the burrs (the

split portion of the sample) shall be 25 mm, see 7.2.7.

7.1.3 Alternative width

When the warp and weft densities of the fabric are very small (for example, less

than 3 pcs/cm), the width of the type-I sample may be greater than 50 mm, and

the width of the type-II sample may be greater than 25 mm.

Note: Test results for different sizes of samples and different tensile speeds are

not the same, and in most cases, there is no comparability.

7.2 Preparation

7.2.1 In order to prevent the end of the sample from being damaged by the

tester fixture, it is necessary to prepare the sample specially. It shall be handled

by the steps of 7.2.2 ~ 7.2.8.

7.2.2 Cut a piece of hard paper or cardboard, of which the sizes are larger than

or equal to the size of the template (5.2.1).

7.2.3 Lay the fabric completely on hard paper or cardboard; ensure that the

warp and weft yarns are straight, unbent and perpendicular to each other.

7.2.4 Place the template (5.2.1) on the fabric; make the entire template on hard

paper or cardboard; use the cutting tool (5.2.2) to cut a piece of fabric and hard

alternative width (see 7.1.3). In this case, the number of yarns of all the samples

of the same fabric shall be the same. The actual width of each sample shall be

measured; the arithmetic mean of the widths of five samples shall be calculated

and corrected to 1 mm, which shall be included in the test report.

8.1 Humidifying environment

Humidify under the standard environment, where the temperature is (23±2) °C

and relative humidity is (50±10) %, which is specified in GB/T 2918-1998; the

humidifying time is 16 h or agreed by stakeholders.

8.2 Test environment

The test shall be carried out in the same environment as the humidifying

environment.

9.1 Adjust the fixture (5.1.1) spacing; the spacing of the type-I sample is 200

mm ± 2 mm; the spacing of the type-II sample is 100 mm ± 1 mm. Make sure

that the fixtures are aligned and parallel. Pass the longitudinal axis of the

sample through the midpoint of the front edges of the two fixtures to clamp one

of the fixtures. Before another fixture is clamped, cut the lining paperboard from

the middle of the sample that is perpendicular to the longitudinal axis of the

sample; evenly apply pretension throughout the width direction of the sample;

the pretension shall be (1 ± 0.25) % of the expected force; then, clamp the other

fixture.

If the strength machine (5.1) is equipped with a recorder (5.1.3) or a computer,

the pretension can be applied by moving the movable fixture. The pretension

value shall be subtracted from the breaking load.

9.2 Under the condition that is compatible with different types of testers and

different type of samples (according to provisions of 5.1 and 7.1), start the

movable fixture and stretch the sample to break.

9.3 Record the final breaking force. Unless otherwise agreed, when the fabric

is broken in two or more stages, such as a double-layer or a more complex

fabric, record the maximum strength at which the first set of yarns breaks and

use it as the tensile breaking force of the fabric.

9.4 Record the elongation and accurate to 1 mm.

a) Description in accordance with this Part;

b) Identify the necessary details of the tested fabric;

c) Sampling methods that are different from this Part;

d) Humidifying and test environment;

e) If the humidifying time is not 16 h, the humidifying time shall be indicated,

and expressed in hours (h);

f) If the sample number in the warp or weft direction is lower than the

minimum number that is specified in the standard, the sample number

shall be indicated;

g) Sample type;

h) If the sample width is different from the width that is specified in the

standard, the sample width shall be indicated;

i) The type of adhesive and the method of application, and the drying and/or

curing system that is used;

j) The breaking force in each direction (warp or weft), and each effective unit

value;

k) The elongation in each direction (warp or weft), and each effective unit

value;

l) The number of samples that are rejected during the test;

m) The applied tester and fixture type; if it is CRL or CRT tester, provide the

breaking time;

n) Any operational detail that is not specified in this Part and condition that

may affect the test result.

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