1.Instrument

1.1 Pendulum-type tearing force testing machine, the test cloth sample is fixed between two jaws, one side is movable and the other side is a fixed structure. The movable jaws are connected with the pendulum that can fall due to the influence of gravity. . The pendulum provides the force to tear the fabric during testing. This instrument consists of the following components.

1.1.1 A sturdy frame to support the pendulum and fixed jaws, as well as a cutter and measuring tape for notching, installed horizontally and to prevent movement during testing.

1.1.2 The pendulum can swing freely along the horizontal bearing, that is, the pendulum is raised to the starting position (the pendulum stops) and released immediately.

1.1.3 Mechanical or electric device used to measure the maximum amplitude of the first swing, that is, the maximum ability to tear the cloth sample, and give a direct reading of the tear.

1.1.4 The movable clamp is integrated with the pendulum. The fixed clamp is integrated with the frame. The distance between the clamps is 3 ± 0.5 mm so that the knife edge can pass through. After the cloth sample is placed in the clamp, it is aligned with the rotating axis of the pendulum. Parallel, this plane forms an angle of 27.5 ± 0.5° with the vertical line of the rotating axis. The distance between the rotating axis and the upper edge of the clamp is 104 ± 1 mm. There is no exact specification for the size of the clamp face. The width is generally 30-40 mm. A height of 20 mm, but no less than 15 mm is suitable.

1.1.5 Use a sharp blade to make a 20 ± 0.5 mm incision between the two clamps before tearing the cloth sample.

2. Conditions for equilibration and testing

Climatic conditions for equilibration, testing, etc. are described in ISO 139.

3. Preparation of test fabric samples

3.1 Two sets of test fabric samples need to be cut from each piece of test cloth, one set in the warp direction and one set in the weft direction. The short side of the fabric sample should be accurately parallel to the warp or weft direction to ensure that the tear is within the notch.

3.2 Each set of cloth samples should include at least 5 pieces of test cloth or more, and the samples should be taken according to Clause 5 or Appendix C. Each pair of test cloth samples should not contain the same warp or weft yarns, and the cloth samples should be at least 150 mm away from the edge of the cloth. Cut.

3.3 Appearance dimensions: The fabric sample is cut as shown in Figure 1. Slightly different shapes are acceptable, as long as the torn length remains at 43 ± 0.5 mm; 100 ± 2mm; 5 ± 0.5mm; 12 ± 0.5mm; 43±0.5mm; 75±2mm; 20±0.5mm; 50±1mm;

3.4 Cut the fabric sample. The short side of each test fabric sample is parallel to the warp or weft direction. If the short side is parallel to the warp direction, the tearing direction passes through the weft direction, otherwise the tearing direction passes through the warp direction.

4.Testing procedures

4.1 Select the mass of the pendulum so that the measured value is within the range of 15% to 85% of the corresponding scale, check the zero position of the instrument, and raise the pendulum to the starting position.

4.2 To fix the cloth sample, put the cloth sample into the clamp (such as 1.1.4), make the long side of the cloth sample parallel to the upper edge of the clamp, clamp the cloth sample in the center of the clamp, and make the bottom edge close to the bottom of the clamp. , use a cutter to make a 20 ± 0.5 mm incision so that the torn length is 43 ± 0.5 mm.

4.3 Press down the pendulum stopper to release the pendulum, and restrain the pendulum when it swings back. Do not interfere with the pointer position. Use N to read the scale reading or the digital display reading. Depending on the type of instrument used, the scale reading should be multiplied by an appropriate The factor number is converted to the result value in Newton tons. Check whether the result is between 15% and 85% of the full scale value. Repeat the test on at least five cloth samples in each direction.

4.4 Observe whether the tearing process is in the direction of stress. The following conditions are correct: a) no yarn slips out of the fabric sample; b) no slippage at the clamp; c) the notch area remains after complete tearing Within 15mm width. Otherwise the result should be discarded.

4.5 This method does not apply if three or more test results are rejected.

5. Calculation and presentation of results

5.1 Calculate the arithmetic mean of the tear force in each test direction, represented by N, and retain two significant figures.

5.2 If required, calculate the coefficient of variation to the nearest 0.1% and the 95% confidence interval, expressed as N and retain two significant figures.

5.3 If required, the minimum and maximum tear strength of the fabric sample in each direction should be recorded.

6.Test report

6.1 The test report should include the following information.

a) Parts related to EN ISO13937 and test dates.

b) Certification of test fabric samples and sampling procedures (record sampling procedures if necessary).

c) Measuring range used.

d) The number of fabric samples tested and the number rejected and the reasons for rejection.

e) Observe abnormal tear behavior.

f) Any deviation from the procedures given.

6.2 Test results

a) The average tear force in the warp and weft directions, expressed as N. If only 3 or 4 test fabric samples are correctly torn, record the tear force results of the correctly torn fabric samples separately.

b) If required, record the coefficient of variation of tear force, expressed in %.

c) If required, record the 95% confidence interval of the tear force, expressed as N.

d) If required, record the minimum and maximum tear force values in each direction, expressed in N.

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