The trapezoidal test method of the fabric tear strength tester is carried out according to ASTM D5587-2003 by a constant rate elongation tester (CRE). Qisnun Precision Electromechanical Technology Co., Ltd. is a manufacturer of textile testing instruments, which can provide various textile testing instruments, welcome customers who need to inquire in time.
According to Standard Group R&D Technical Engineer, this test method is applicable to most fabrics, including woven fabrics, airbags, blankets, pile fabrics, knitted fabrics, laminated fabrics and cut pile fabrics. The fabric can be raw, resized, coated, resin treated or otherwise treated. Instructions are provided for wet-treated and non-wet-treated specimens.
Tear strength tested by this method must be pre-tearede before the test. The test values obtained are not directly related to the force required for the pre-tear. There are two methods of calculating the tearing strength of the trapezoidal method: the force value of a single peak and the average force value of five peaks.
Test method: Mark an isosceles trapezium on the rectangular sample. The copy is torn with a notch in the middle of the short side of the trapezium, pre-torn. The two non-parallel sides of the trapezius are clamped onto the parallel clamps of the weight machine. The distance between the jaws increases continuously and the force applied causes the incision to enlarge in the sample. Simultaneously, force values are recorded and all forces for successive tears are calculated from an automated chart recorder or microprocessor based data collection system.
Laboratory samples: for access testingptation, a sample is taken from each batch of samples, the sample corresponds to the full width of the fabric, i.e. approximately 1 meter in length. For roll fabrics, the sample taken must not contain the outer layer or the inner core of the roll.
Test Specimens: From For each lab sample unit, select five samples each in the machine direction (warp) and perpendicular to the machine direction (weft).
Test direction: The length direction is the test direction.
Sample cutting test: If the sample is used for machine direction testing, the long side of the sample is parallel to the machine direction; if the sample is used for testing in the vertical machine direction, the long side of the sample is perpendicular to the machine direction. If the specimen is to be tested wet, cut the wet specimen next to the dry specimen. Keep the label for identification.
When machine cutting the fabric, be sure to keep the short side threads parallel to the gauge, so that when the tear is in the direction of the cut, the tear will occur between these wires and not transversely. For yarns, this consideration is especially important when testing curled fabrics.
Cut the sample in a direction representative of the length and width, and in a more advisable direction. The sand method consists of cutting in the diagonal direction of the sample and the distance from at the selvedge is not less than 1/10 of the width. Make sure the sample has no creases, creases or wrinkles, and avoid the sample being stained with oil, water, grease, etc. during operation.
Use the template to mark an isosceles trapezium on the sample and cut an incision 15 mm (0.625 in) long in the middle of the 25 mm (1 in) side.
Operational steps:
1. Test the preconditioned samples in a standard atmosphere with a temperature of 21±1°C (70±2°F) and a relative humidity of 65±2%. Unless otherwise stipulated in the standard or the contract.
2. Fix the sample along the non-parallel sides of the trapezium. The edge of the dart is aligned with the 25mm side of the trapezoid, so the cut is in the middle of the two darts. The short sides of the trapezoid are stretched out and the long sides are tucked in.
For wet testing, the sample is removed from the water, immediately mounted on the instrument according to normal procedures, and the test is performed within two minutes of removing the sample from the water. If the time between taking the sample out of the water and starting the weight system exceeds two minutes, the sample is invalid and a new sample is taken.
3. Start the machine and record the tear force. Theretear strength may be a single high value, or multiple large or small values may appear.
4. Once the sample has been torn to a length of approximately 6 mm (0.25 inches), record a series of maximum values of the single tear value. Once the tear is approximately 75mm (3 inches) long or the fabric* is damaged, reset the mandrel.
If the tissue slips in the forceps or if more than 25% of the tissue is broken within 5 mm (0.25 in) of the jaw, the jaw should be doubled and the tissue under the jaw must be padded. lay down or correct the clamping surface and note the changes made in the report.
After the correction in 6.4.1, more than 25% of the tissue is still fractured within 5 mm (0.25 in) of the jaws, so this test method cannot be used for this fabric.
If the tear is not in the direction of the applied force, save it.
Remove the sample and repeat steps 2-5 until 5 samples in two base directions from each lab sample group are tested.
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