GB/T 45711.1-2025Leather - Determination of tear load - Part 1: Single edge tear (English PDF)

6.2 Specimen Preparation

Use a die cutter (5.3) to cut six specimens from the grain surface (if the grain surface cannot be identified, cut from the usable surface). Three of these specimens shall have their long sides parallel to the ridgeline, and the other three specimens shall have their long sides perpendicular to the ridgeline. If the ridgeline direction cannot be identified, respectively take specimens from two mutually perpendicular directions.

If more than two samples from the same batch need to be tested, at least one specimen shall be cut from each sample in each direction, with a total of no less than three specimens in each direction.

6.3 Specimen Conditioning

Perform in accordance with the provisions of QB/T 2707.

6.4 Thickness Determination

Perform in accordance with the provisions of GB/T 45705.The measurement location is the two points between the endpoint A of the cut and the perpendicular distance of the short side (not the direction of the cut) of the specimen.

7.3 Operate the tensile testing machine, until the specimen tears. Record the force-distance

diagram during the test. If the specimen does not tear along the direction of the cut, re-perform sampling for the test. If the tear still does not occur along the direction of the cut, note this in the test report.

7.4 Repeat steps 7.2 ~ 7.3 to test the remaining specimens.

8.1 Tear Load

8.1.1 Calculation method

The tear load of the specimen is the arithmetic mean of the force values on the force-distance diagram and is calculated as follows.

Divide the force-distance diagram from the first peak to the last peak into four equal parts. The first and fourth parts shall not be included in the result calculation. Calculate the average force (i.e., tear load) from the two middle parts and express it in Newtons (N).

If the instrumental calculation method is used, consider all force data points in the two middle parts; this method is recommended for more accurate calculation results.

If the manual calculation method is used, respectively select and record the two highest peaks (maximum values) and the two lowest valleys (minimum values) from the two middle parts (a total of eight values). The peaks or valleys suitable for calculation shall show at least a 10% increase or decrease. Calculate their arithmetic mean. If this method is used, it shall be noted in the test report.

NOTE. different calculation methods use different force data points, so the results of the two calculation methods may differ.

In the event of a dispute or arbitration, the results obtained using the instrumental calculation method for standard-sized specimens shall prevail.

In some cases, the lack of discernible peaks and valleys makes it quite difficult to obtain valid values from the force-distance diagram. In such cases, perform re-sampling for the test.

8.1.2 Presentation of results

The results are the arithmetic mean of the test results for each specimen in each direction, accurate to 0.1 N.

If necessary (e.g., upon request by the customer), the results may be the arithmetic mean of the test results for all specimens.

8.2 Tear Strength

The tear strength of the specimen is calculated in accordance with Formula (1).

Where,

T---the tear strength, expressed in (N/mm);

F---the tear load, expressed in (N);

t---the specimen thickness, take the arithmetic mean of two measurement points, expressed in (mm).

The result is the arithmetic mean of the test results for each specimen in each direction, accurate to 0.1 N/mm.

If necessary (e.g., upon request by the customer), the result may be the arithmetic mean of the test results for all specimens.