The m/c used here is a vertical strength tester .Therefore, the experiment has two objects:
1. To find out the strength of the fabric.
2. To be precise in testing.
Theory:
Strength is a measure of the steady force necessary to break a material and is measured in pound. The m/c works in Pendulum lever principle with constant rate of extension.
Assuming the specimen to be extensible and an absence of any dynamic effects, we get from the figure:
Fr = Mgr = MgRsinq
As the value of M,g,R and r are constant, therefore
F ยต sin q.
According to the applied force the m/c dial gives us the strength in lb on the basis of this q.
Apparatus:
1. Cotton fabric
2. Fabric strength tester
3. Scissors
M/c specification:
- The Fabric Strength Tester
- Goodbrand & Co. Ltd.
- Capacity: 250lb
Testing atmosphere:
Temperature – 29oC and relative humidity – 76%
Standard atmosphere: temperature – 20oC and relative humidity - 65%.
Sample:
Size – 8inch X 2inch.
No. of sample – 20 (For warp way-10, For weft way-10).
Working procedure:
1.At first 12inch × 2inch fabric was cut out from a big piece of fabric. The excess amount of fabric was cut because the two jaws will require at least 2inch each to grip the fabric. Thus 10 samples were cut down for testing.
2.Now, the first sample is fixed with the upper jaw J1 and the lower jaw J2.
3.The m/c is started and observed the dial until the sample is torn out.
4.When the sample is torn out the m/c is stopped and the reading is taken.
5.By this way the others’ reading are taken.
6.At last average and CV% are calculated.
Data:
Warp way:
Reading | Fabric strength (lbs) | Avg strength (lbs) | SD | CV% |
1 | 80 | 82.3 | 3.23 | 3.92 |
2 | 87 | |||
3 | 86 | |||
4 | 78 | |||
5 | 80 |
Weft way:
Reading | Fabric strength (lbs) | Avg strength (lbs) | SD% | CV% |
1 | 71 | 70.4 | 2.9 | 4.24 |
2 | 64 | |||
3 | 69 | |||
4 | 72 | |||
5 | 74 |
Calculation: 
Result:
The warp way fabric strength= 82.3 lbs
The weft way fabric strength= 70.4 lbs
The CV% for warp way fabric strength=3.92%
The CV% for weft way fabric strength=4.24%
Remark:
The strength of a fabric varies with (1) EPI variation,(2) PPI variation, (3) Count variation. The strength of the fabric also varies if the length and width of the fabric to be tested is changed. If we take a sample which size is 3inch×6inch and another sample size 2inch×6inch then the strength of the first sample will be greater than the second one. Thus if we increase the length of the second sample then the strength of the second sample will be decreased. The strength of the fabric also depends on the construction of the fabric.
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