Tear strength is the force required to advance a previously opened tear in fabrics. Tear strength of woven fabrics can be determined using different methods such as tongue method, trousers method, wing method and ballistic pendulum method. The method to be mentioned here is the tongue (double tearing) method. According to this method, the tear strength is determined according to the TS EN ISO 13937-4 standard. Tongue-shaped test specimens with double tear strength are used. ( TS EN ISO 13937-4 )
Universal tester, ruler, scissors and gripper jaws.
Samples should be conditioned for 24 hours under standard atmospheric conditions before starting the test. 5 sets of test samples are prepared, 5 of which are weft and 2 of which are warp. Care is taken to ensure that the samples do not contain the same weft and warp threads. Rectangular specimens with dimensions of 220 mm x 150 mm are marked as test specimens. It is marked across the width of the test specimen 20 mm before the long edge, then 70 mm below. Then the test sample is divided into 50 equal parts 3 mm wide and drawn with a 20 mm ruler under 100 mm along its length. A tongue shape is formed in the middle. It is cut starting from the marked 100 mm line with the help of scissors. Mark the end of the tear at which the tear will end, 25 mm above the uncut bottom edge of the rectangular test specimen. For the test specimen with the long side parallel to the warp, the tearing line is tested "Length to Weft" and for the test specimen whose long side is parallel to the weft, the tear is tested "Longitudinal Warp".
The test specimens prepared in the form of tongues are subjected to testing in the tensile device. The pulling device must be one with one of the holders stationary and the other moving at a constant speed. Here, the gauge length of the device is set to 100 mm and the elongation rate to 100 mm/s. Then, the prepared test specimens are placed symmetrically, with the tongue part parallel to the movable gripper jaw and the lower part parallel to the lower jaw of the device at the 70 mm marked parts. The values are reset by pressing the force and elongation keys on the PC screen of the device. Then the up arrow key is pressed and the test starts. In the meantime, the movable upper jaw of the pulling device moves upwards and starts to tear by forming peaks. When the tearing process reaches the point we marked as 25 mm from the bottom edge, the test is stopped and the tearing force is recorded. The test is considered to be correct if there is no slippage in the jaws, no yarn breaking from the fabric, tearing along a straight line and the tearing is completed while the sample is being tested. In this way, at least 5 test samples are taken and the test is repeated. The arithmetic average of all recorded yarns gives us the test result in Newtons.