Standard Test Method for Breaking Force and Elongation of Textile Fabrics (Strip Method)

 

Theory:

 

The Strip Test for textiles and fabrics is very similar to the grab method however the material is gripped at the end, and the grip faces must be wider than the samples. The strip test is used to measure the breaking strength of the material. A Universal Testing Machine that is able to pull at a Constant Rate of Extension (CRE) is required for this test to be successful. The ISO version of this test is ISO 13934 - 1. 

 

There are several criteria that the test must meet beyond just a successful break somewhere in the middle of sample. One being the speed of the test. The speed of the crosshead does not matter so much as the time until break. If the tensile tester runs too slow or too fast, the individual fibers have time to readjust and slip which can corrupt the data. Generally the test needs to be performed within 20 seconds from start to stop. 

 

Geometry:

Sample specimens can be of varying width, however 1 inch wide samples are most common. Wider grip face inserts are available for samples of different sizes. Most test strips are between 8-12 inches long.

 

Solution:

Pneumatic grips are popular for these types of tensile tests since the material is flexible. The pneumatics are able to impart a constant lateral force on the sample that is typically higher than that of a vise. A mechanical vise grip can sometimes slip, causing the test to fail. Other common things to watch out for is the specimen breaking at the grip face. Other types of grips and fixtures are available for this type of procedural method when vise grips fail. The most common alternative textile testing fixture is the wrap grip, however usage of such will violate the exact ASTM specifications.