This is a single tear method to determine fabric tear force. This method specifies a procedure known as the wing test that uses a test specimen that is cut into two wings for clamping inclined at a defined angle to the thread direction. The tear force measured is the force required to propagate a previously started single tear.
In general, the method is mainly applicable to woven textiles fabrics, but it may be applicable to fabrics produced by other techniques. Is not applicable to knitted fabrics, woven elastic fabrics and nonwovens, to which the trapezoidal test method is preferably applied. Due to the clamping of the specimen wings inclined to the threads to be torn, the test can be used for most types of fabrics without causing a transfer of tear and it is less susceptible to withdrawal of threads than other tear tests.
In principle, a specifically shaped test specimen is cut form two wings and one side is mechanically stressed so that the stress is concentrated at a cut in such a way as to cause tearing in the desired direction. The wings of the specimen are clamped inclined to the direction of the threads to be torn. The force to continue the tear is over a specified distance at a constant rate of displacement, and the tear force is calculated from the force peaks. To record the test it is important to have a high-speed intelligent test data logging rate. This is the transfer data rate to the PC of 100 Hz or more to capture and record all the peaks and troughs.
We used pneumatic action grips with rubber coated jaw faces for clamping of the material fitted to a tensile testing machine. While manual action grips will work, many of our users prefer the pneumatic action grips for ease of use, productivity, and better repeatability. Pneumatic action grips allow you to set a clamping pressure, while the manually operated grips depend on the operator's strength (which may not be so repeatable). We find that gripping pressure and specimen alignment are very important in these tests. Too much gripping pressure can produce premature breaks, while not enough gripping pressure can lead to specimen slippage or breaks at or near the jaws.
These grips are usually fitted to single-column or dual-column table-top design. Using testing software, such as Bluehill® 2, test method is used to input specimen details, set the desired test control, automatically calculate the desired results and statistics, and produce a test report all in accordance with the standard.
We suggest reviewing ISO13937-3 to fully understand the test fixture and results requirements