Tear Strength Test Procedure

Scope and Principle

To determine the force required to tear a fabric, starting from a cut in the fabric. This test is for woven apparel fabric only.
Apparatus

Elmendorf Tear Strength tester with either
Pendulum B (Range 0 – 1631g) or
Pendulum C (Range 0 – 3262g)
or
Elmatear (Pendulum A, B or C)

Note: For accuracy, the tear strength of the samples must fall between 20% and 80% of the force range of the selected pendulum.

Metal Calibrated Ruler (150mm).
De-sized, bleached cotton lawn without any finish.
Tear Strength tester
 

 

 

 

 

 

 

 

 

 

 

 

Specimen Preparation

Do not use fabric within 5cm of the selvedge.

Prepare 3 specimens parallel to the warp direction and 3 specimens parallel to the weft direction.

Each specimen should measure 100mm x 63mm.

Weft Tears ~ specimens have the 63mm dimension parallel to the warp and the tear is across the weft threads.

Warp Tears ~ specimens have the 63mm dimension parallel to the weft and the tear is across the warp threads.

The 63mm dimension is critical to the test and must be frayed down. One of these edges is then trimmed to the last thread to give a smooth edge which sits on the base of the clamps.

It is not necessary to fray the 100mm dimension.

The specimens are cut randomly from the fabric, ensuring that they do not contain the same set of warp and weft threads.

Place a direction line, outside the test area, parallel to the warp on each sample before cutting from the main piece.
Conditioning

Condition the prepared test specimens for a minimum of 4 hours in a conditioned atmosphere of 20 + 2C and
65 + 4% RH before testing.

The equipment must be sited and the test carried out in this atmosphere.
Equipment Calibration

For the Elmendorf, calibrate before each use, as follows:-

1) Ensure that the spirit level is central within the defined circle. Use the right hand knob to adjust if necessary.

2) Check the pendulum is balanced centrally, by releasing it from the start position and lining up so that the reference mark in the centre of the pendulum is in line with the centre pointer on the base of the machine. Use the left hand knob to make any adjustments, ensuring that the release lever is depressed.

3) To check that the pointer is zeroing, place the pendulum in the start position. Ensure the specimen clamps are closed and the pointer is in the stop position.

4) Release the pendulum and allow to swing freely, allow one full swing cycle before releasing the stop to act as a brake.
Read off the scale with the pointer at eye level. The pointer must be + 3mm from the zero mark.
To adjust the pointer, move the pointer stop backwards or forwards as necessary.

Repeat steps 2 to 4 a minimum of 3 times to establish that the equipment is calibrated.
For the Elmatear calibrate according to the operators guide.
On ALL Machines Before Commencing the Test

Check the cut length of the knife is 20mm using a piece of cotton lawn.

To do this, fray along one edge of the cotton lawn, then trim up to the last thread to give a straight edge. Clamp this edge into the jaws and make a cut. Using the metal ruler, measure the length of the cut. If necessary adjust the blade backwards or forwards (taking care not to adjust the angle) to achieve a 20mm cut.
Test Procedure ~ Elmendorf

Clamp the specimen in the jaws so that the 100mm side of the sample with the trimmed edge is parallel to the base, i.e. sitting on the base of the jaws.

a) Tighten the clamps and place a 20mm cut in the sample.

b) Set the pointer to the starting position.

c) Depress the pendulum release and allow it to swing through fully, one cycle.

d) Read off and record the position of the pointer on the scale.

e) Repeat the procedure for the two remaining specimens.

Tear Test Procedure

 

 

 

 

 

 

 

 

 

 

 

Test Procedure ~ Elmatear

Refer to Operators Guide.

Calculation of Results

Elmendorf
Pendulum B
Record the average of the 3 results in each direction.
Multiply the average by 16 and divide by 9.81 to convert to grams

Pendulum C
Record the average of the 3 results in each direction.
Multiply the average by 32 and divide by 9.81 to convert to grams

Elmatear
Record the individual results from the machine and calculate the average.
Test Report

Report the test method number and title.

Report the average of the 3 results in each direction to the nearest 0.1g.

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