1 Scope
This part of GB/T 3917 describes a single tear method to determine fabric tear force, known as the wing test using a test specimen cut to form 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 tear.
The test is mainly applicable to woven textile fabrics. It may be applicable to fabrics produced by other techniques. 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 general the method is not applicable to knitted fabrics, woven elastic fabrics and nonwovens, to which the trapezoidal test method is preferably applied.
The method only allows the use of constant-rate-of-extension (CRE) testing machines.
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this part of GB/T 3917. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, the parties to agreements based on this part are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.
GB/T 6529 Textiles — Standard atmospheres for conditioning and testing (GB/T 6529-2008, ISO 139:2005, MOD)
GB/T 16825.1 Verification of static uniaxial testing machines — Part 1: Tension/compression testing machines — Verification and calibration of the force-measuring system (GB/T 16825.1-2008, ISO 7500-1: 2004, IDT)
GB/T 19022 Measurement management systems — Requirements for measurement processes and measuring equipment (GB/T 19022-2003, ISO 10012: 2003, IDT)
3 Terms and Definitions
For the purposes of this part of GB/T 3917, the following terms and definitions apply.
3.1 Constant-rate-of-extension (CRE) testing machine
Tensile-testing machine where one clamp is stationary whilst the other is moving with a constant speed throughout the test.
3.2 Gauge length
Distance between the two effective clamping points of a testing device.
Note: The effective clamping points (or lines) of jaws can be checked by clamping a test specimen under defined pretension with carbon copy paper.
3.3 Tear force
Force required to propagate a tear initiated under the specified conditions.
Note: The tear force is qualified as "across warp" or "across weft" according to whether the tear is made across the warp (warp threads are torn) or weft threads (weft threads are torn) respectively.
Foreword I
1 Scope
2 Normative References
3 Terms and Definitions
4 Principle
5 Sampling
6 Apparatus
7 Atmosphere for Conditioning and Testing
8 Preparation of Test Specimens
9 Procedure
10 Calculation and Expression of Results
11 Test Report
Appendix A (informative) Suggested Procedure for Sampling
Appendix B (informative) Example of Pattern for Cutting out Test Specimens From the Laboratory Sample
Appendix C (informative) Sample Calculation of Tear Force
