ISO 3376-2011 pdf download.Leather – Physical and mechanical tests – Determination of tensile strength and percentage extension.
6 Procedure
6.1 Determination of dimensions
6.1.1 Using vernier callipers (4.5). measure the width of each test piece to the nearest 0.1 mm at three positions on the grain side and three on the flesh side. In each group of three measurements, make one at the mid-point E (as shown in Figure 1) and the other two at positions approximately midway between the midpoint E and the lines AB and CD. Take the arithmetic mean of the six measurements as the width of the test piece, w. For soft (“flexible”) leather, the width shall be taken as the width of the press knife.
6.1.2 Measure the thickness of each test piece in accordance with ISO 2589. Make the measurements at three positions, namely the mid-point E and at positions approximately midway between the mid-point E and the lines AB and CD. Take the arithmetic mean of the three measurements as the thickness of the test piece, t.
6.2 DetermInation of tensile strength
6.2.1 Set the jaws of the tensile testing apparatus (4.1) 50 mm ± 1 mm apart if using the standard test piece or 100 mm apart if using the large test piece. Clamp the test piece in the jaws so that the edges of the jaws lie along the lines AB and CD. When the test piece is clamped, ensure its grain surface lies in one plane. The length axis shall be parallel to the traction direction.
6.2.2 Run the machine until the test piece breaks and record the highest force exerted as the breaking force, F.
6.3 Determination of the percentage elongation caused by a specified load
6.3.1 Clamp the test piece between the jaws of the apparatus, as described in 6.2.1. Measure the distance between the jaws at least to the nearest 0,5 mm and record this distance. L0, as the initial length of the test piece for the purpose of the test.
6.3.2 Start the test. Unless the apparatus automatically draws a force/extension curve with the necessary accuracy (see 4.2), follow the distance between the pair of jaws or the sensors as the force increases.
6.3.3 Note the distance, in millimetres, between the pair of jaws or sensors at the instant when the force first reaches the specified value. This distance represents the length of the test piece at this force. L1. Do not stop the apparatus if results from the procedures described in 6.2 or 6.4 are also required.
6.4 DetermInation of the percentage elongation at break
6.4.1 Carry out the steps given in 6.3.1.
6.4.2 Run the tensile test machine until the test piece breaks.
6.4.3 Record the distance between the jaws or sensors at the instant when rupture of the test piece occurs.
This distance represents the length of the test piece at break. -2
6.5 Slippage
If there is slippage of the test piece in either jaw when tested according to 6.2, 6.3 or 6.4, and the slippage is greater than 1 % of the initial jaw separation, reject the result and repeat the determination with a new test piece cut using the large press knife (4.4).ISO 3376 pdf free download.