Determination of tear strength of fabric.

In this experiment the tear strength of the 100% cotton grey fabric was determined by using Falling Pendulum (Elmendorf's) Apparatus. Slit is centrally precut in a test specimen held between two clamps and the specimen is torn through a fixed distance. The resistance to tearing is in part factored into the scale reading of the instrument and is computed from this reading and the pendulum capacity.

Tear strength is the resistance of the fabric against tearing or force required to propagate the tear once it is initiated. The tear strength is required in high performance applications as well as in the conventional textiles i.e. in the industrial applications, bullet proof jackets, tents, worker jeans, sacks, aesthetic apparel and many more applications. This is also important in the industrial textiles where heavy duty work is performed. High tear strength of textiles make sure that the punctures in the fabrics doesn't propagates easily.

Tear strength depends upon:

• GSM of the fabric – more the GSM more tearing strength of the fabric.
• Specific strength of yarn – yarn strength is directly related to the tearing strength of the fabric, the more yarn strength relates to the more tear strength.
• Ends/inch and picks/inch – more ends/inch and picks/inch gives more tear strength when compact or filament yarns are used, but in case of simple ring spun yarn the tear strength may decrease.
• Weave type of fabric – plain weave has the lowest tear strength as compared to the other weave designs.
• Spun or filament yarn – the spun yarn if used in fabric has low tear strength as compared to the filament yarn.
• Knitted or woven fabric – it's easy to tear the knitted fabric as compared with the woven one.
• Type of finishes applied onto the fabric.

Tear strength can be imparted:

• By changing the fiber type at the yarn spinning process.
• By changing staple fibers with the filaments at yarn spinning process.
• By changing weave design, ends/inch or picks/inch and by changing the GSM of the fabric.
• Using composites.
• At the wet processing level using different finishes.
• By adding more layers of the fabric.
• By increasing the twist in the yarn.

The tensile strength of fabric was tested according to ASTM Standard – D1424. Here Elmendorf's Falling Pendulum Apparatus was used to calculate the tear strength of the fabric.

Materials & Equipment:

• Scissor
• Cotton fabric
• Elmendorf's tearing tester
• mm Scale

Procedure:

• Cotton fabric was taken.
• Warp and weft direction of the fabric was identified.
• Two strips were cut from the fabric in both directions having dimensions of 100 x 63.5 mm.
• The sample was then fixed in the jaws of the tearing tester.
• A cut of 20mm was made along the width of the fabric using the cutter in the tearing tester.
• By using falling pendulum of the tearing tester the fabric was tear and the readings were noted from the Elmendorf's tester's scale.

Observations & Calculations:

Fabric type:

Fabric = 100 % cotton

Count of yarn used in the fabric = 60 Ne

Weave Design = 4 x 1 Twill weave

Warp yarn = Sized

Weft-wise fabric Tear strength

Sr. #	Tear Strength (g)
1	1600
2	1800
3	1400
4	1500
Mean Values	1575

 

Warp-wise fabric Tear strength

Sr. #	Tear Strength (g)
1	2560
2	2360
3	2760
4	2600
Mean Values	2570

 

Results & Discussion:

Tear Strength

Weft-wise tear strength = 1575 Kg

Warp-wise tear strength = 2570 Kg

The results show that the warp-wise tear strength of the fabric is more than that of the weft-wise tear strength of the fabric. The fabric had a twill 4 x 1 weave design. This shows that the warp yarns are much more than that of the weft yarns, that's why the warp yarn strength is much more than that of the weft yarn.

Conclusion:

This experiments showed that the warp-wise tear strength of fabric is greater, hence the fabric is more stable along the warp-wise direction.