The Exchange Test Method
A-11: Tear Strength
Issue Date: 30 Apr 1993
Revision Date: 09/30/2011
-
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.
-
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.
-
REFERENCE:
3.1 ASTM D 1424-09, Standard Test Method for Tearing Strength of Fabrics by Falling-Pendulum Type (Elmendorf-Type) Apparatus.
-
APPARATUS:
- 4.1 Falling pendulum (Elmendorf) tear tester - See 8.
- 4.2 Cutting die
-
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:
- 0-1600g capacity (20g divisions) - no add-on weight
- 0-3200g capacity (50g divisions) - one add-on weight
- 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.
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.
REPORT:
Report the above figure as tearing strength of the sample or item tested.
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