GB/T 13772.1-2008Textiles - Determination of the slippage resistance of yarns at a seam in woven fabrics - Part 1: Fixed seam opening method (English PDF)

6.1.1 Metrological confirmation of the constant rate of extension (CRE) testing machine

shall be performed in accordance with GB/T 19022.The constant rate of extension (CRE) testing machine shall have the general characteristics specified in 6.1.2 ~ 6.1.8.

6.1.2 The tensile testing machine shall have the function of indicating or recording the maximum force applied to the specimen to extend it until failure. Under conditions of use, the instrument shall be of class 1 accuracy in accordance with GB/T 16825.1.At any point within the full scale of the instrument, the error in indicating or recording the maximum force shall not exceed ±1 %, and the error in recording extension shall not exceed ±1 mm.

6.1.3 If a data acquisition circuit and software are used to obtain the force value, the data acquisition frequency shall not be less than 8 times per second.

6.1.4 The instrument shall be able to set a tensile speed of 50 mm/min with an accuracy of ±10 %.

6.1.5 The instrument shall be able to set a spacing length of 100 mm.

6.1.6 The center point of the instrument clamps shall be on the tensile axis, the clamping line shall be perpendicular to the tensile line, and the clamping faces shall be on the same plane. The clamping faces shall be able to hold the specimen without slippage, and shall be flat, without shearing or damaging the specimen. If a smooth clamping face cannot prevent specimen slippage, other types of clamps shall be used. Appropriate padding material may be used on the clamping faces.

6.1.7 The dimensions of the specimen clamped during the grab test shall be (25 mm ±

1 mm) × (25 mm ± 1 mm). This dimension can be achieved using one of the following methods.

a) The width of the rear clamping face is 25 mm, and the length is at least 40 mm (50 mm is preferred). The length direction of the clamping face is perpendicular to the tensile line. The dimensions of the front clamping face are the same as the rear clamping face, and its length direction is parallel to the tensile line.

b) The width of the rear clamping face is 25 mm, and the length is at least 40 mm (50 mm is preferred). The length direction of the clamping face is perpendicular to the tensile line. The dimensions of the front clamping face are 25 mm × 25 mm.

6.1.8 If the tensile testing machine is not computer-controlled, a device for recording the force-extension curve is required.

6.2 Equipment for cutting specimens.

6.3 Sewing machine. An electrically controlled single-needle lockstitch machine

capable of sewing the 301 stitch type in FZ/T 01019 (see Figure 1).

The 301 stitch consists of two threads. one needle thread and one bobbin thread. A loop of needle thread is passed through the fabric from the needle side, protruded on the other side to interlace with the bobbin thread; tighten the thread to position the interlaced loop in the middle of the fabric layer.

This stitch is sometimes formed with a single thread, in which case the first stitch differs from subsequent consecutive stitches.

At least two stitches shall be used to describe this stitch type.

Figure 1 -- 301 stitch type

6.4 Sewing machine needles. Throat plate and feed dog, see Table 1 and 9.1.

6.5 Sewing thread. Suitable thread, as specified in Table 1.

6.6 Measuring ruler. Graduation value of 0.5 mm.

9.1 Adjustment of sewing machine

When sewing double-layer test fabrics, the needle is passed through the throat plate and feed dog, and the machine is adjusted to ensure that the stitch density for the specimen complies with the provisions in Table 1.

Table 1 -- Sewing requirements

Remove the bobbin case from under the throat plate of the sewing machine, pinch the thread end protruding from the bobbin case, slowly unwind the bobbin thread a length from the bobbin, and adjust the spring clip on the bobbin case so that the bobbin thread unwinds from the bobbin at a uniform speed during sewing. Reinstall the bobbin case on the sewing machine and adjust the tension of the needle thread passing through the needle. During sewing, interlace the needle thread with the bobbin thread. After shrinkage, ensure that the interlaced loops are in the middle of the fabric layer (see

Figure 1).

9.2 Cutting and sewing of specimens

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