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AAFES TEST METHOD
A-11: Tear Strength
| Issue Date: 30 Apr 1993 |
Revision Date:
08/18/2004 |
1. PURPOSE AND SCOPE:
To determine the tearing strength of woven fabrics. Tear strength
or resistance to tearing is of importance in fabrics such as those used for shirting,
blouses, dresses, interlining, etc. Tear strength tests are not suitable for knit fabrics,
felt, or non-woven fabrics with the possible exception of machine direction tears in some
light-weight non-woven fabrics.
2. PRINCIPLE:
Force required to propagate a rip starting from a cut in a woven fabric is
measured by grasping fabric with a movable clamp on one side, and by a fixed clamp on the
other side, with the fabric split centered between the two clamps. Then as the pendulum is
released, the specimen is torn at the split. The tearing force, in grams, is read directly
off of the graduated scale on the pendulum.
3. REFERENCE:
3.1 ASTM D 1424-96, Standard Test Method for Tearing Strength of Fabrics
by Falling-Pendulum Type (Elmendorf) Apparatus.
4. APPARATUS:
4.1 Falling pendulum (Elmendorf) tear tester - See 8.
4.2 Cutting die
5. PROCEDURE:
5.1 Cut three specimens in warp and filling (machine direction and
transverse direction in case of non-woven fabric), using a specially shaped die.
5.2 Indicate the direction (warp and filling, or length and width, or machine and
transverse) on each specimen with arrows.
5.3 Condition the specimens for a minimum of 2 hours at 21° +/- 1C (70° +- 2F)
temperature and 65% +/- 2% relative humidity.
5.4 Set the capacity of the tester to one of the following:
a. 0-1600g capacity (20g divisions) - no add-on weight
b. 0-3200g capacity (50g divisions) - one add-on weight
c. 0-6400g capacity (100g divisions) - two add-on weight
5.5 Raise the pendulum to the starting position and set the pointer on the zero mark,
at the center of the pendulum.
5.6 Fasten the conditioned specimen securely in the clamps.
5.7 Depress the pendulum stop as far as it will go, thus releasing the pendulum.
5.8 Hold down the stop until after the pendulum makes a complete forward swing, and
catch the pendulum on the return swing by the hand without disturbing the position of the
pointer.
5.9 Read the scale to the nearest whole scale division for the capacity used.
5.10 Repeat 5.5 through 5.9 and record data from 3 specimens.
6. EVALUATION:
6.1 Calculate the average tearing strength of the three specimens in
grams for both directions.
6.2 To convert tear strength, which is in grams, to pounds, divide it by 453.6.
7. REPORT:
Report the above figure as tearing strength of the sample or item tested.
8. NOTES:
The Thwing-Elmendorf Tear Tester can be obtained as Textile Model 60-400 from
Thwing- Albert Instrument Co., 10960 Dutton Road, Philadelphia, PA 19154, tel:
215-637-0100, fax: 215-632-8370, e-mail: thwingpa@aol.com
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