What is the difference between the Tensile Testing Methods?
The Strip Method (AS2001.2.3.1)
The Strip Method uses a sample of fabric (50mm wide x 200mm long) and the complete width of the specimen is gripped in the jaws of the testing machine. The fabric is extended at a constant rate of 100mm/min* until the fabric ruptures, and the maximum force and the elongation at rupture is recorded in Newtons per 50mm (N/50mm).
* This is based on the fabric having a gauge length of 200mm and elongation at break between 8% and 75%.
The Grab Method (AS2001.2.3.2)
The Grab Method uses a sample of fabric (100mm wide x approx 100mm long) and the centre part of the specimen is gripped in the jaws of the testing machine. The fabric is extended at a constant rate of 50mm/min until the fabric ruptures, and the maximum force is recorded in Newtons (N).
It is important to recognise the differences between each method and to specify the method used as the results can vary, as demonstrated in the table below. The variation is due mainly due to the effective width of the fabric being extended, with a strip method effective width is limited solely to cut width of the sample (in the case above 50mm), whereas the grab method includes of the part of the sample held by the jaws as well as a proportional effect of the sample overhanging the jaws.