ASTM D2261 specifies a simple procedure for tearing a textile fabric. Woven and non-woven materials can be made from many different types of fiber materials including cotton, nylon, polyester, and wool. Fabric materials are often combined to create hybrid textiles with multiple characteristics. These hybrid materials must be tested to ensure both quality, as well as manufacturability. As with most textile testing, this method must be performed on a CRE machine, usually at 12 inches per minute. Other speeds can be used to simulate different real world scenarios.
Sample geometries for this test are usually either a 1 or 2 inches wide and over 6 inches long. The specimen is cut in the middle in order to create the two split tongues. One side is secured in the top grip, while the other is attached to the bottom fixture.
Vise grips are most commonly used for this test, similar to the other ASTM tests for textiles. Pneumatic vise grips work great because they allow for a more uniform lateral force on the sample which helps with standardization between data sets.
The analysis and calculation for this test involves taking an average of the 5 highest peak loads to determine tear strength. The reason for this is because as the test progresses, individual fibers will be subjected to tensile forces which pull and ultimately break the fibers. This will create a series of peaks and troughs on the force curve which correspond to the imperfect nature of a woven textile. Non-woven materials can also be tested under this standard, however their force curves tend to look more uniform and less volatile.