This method is used to investigate the tear strength of flexible cellular polymeric materials that have a specified thickness. This test is for the determination of peak force and the tear strength characteristics of the product for a given rate of displacement.
In principle, the test specimen is clamped in the jaws of the testing machine, making sure that the test specimen is properly gripped. A force is applied at a constant rate of displacement - tearing the specimen until fracture. ISO 8067 allows for two types of specimens: Method A uses a trouser tear specimen, while Method B uses an angled test piece.
The challenges of testing to this standard:
- Data collection
- Specimen gripping
- Data collection – The tear force is calculated from the force peaks collected throughout the test. We recommend using a high-speed intelligent test data logging rate found in Bluehill® Universal so users can be sure all critical peaks are captured.
- Specimen gripping – We recommend pneumatic side 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 side action grips allow you to set a clamping pressure, while the manually operated grips depend on the operator's strength. 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 machines.
We suggest reviewing ISO 8067:2008 to fully understand the test fixture and results requirements.