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Determination of fabric stiffness by Shirley Stiffness Tester

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Determination of fabric stiffness by Shirley Stiffness Tester.

Introduction:

Stiffness is a special property of a fabric. It is the tendency of the fabric to keep standing without any support. It is a key factor to study of handle and drape.

Object:

  1. To measure the stiffness of the given sample.

Theory:

A rectangular strip of fabric, 6” ×1”, is mounted on a horizontal platform in such a way that it over change, like a cantilever, and bends downwards as shown in figure.

From the length l and the angle θ  a number of values are determined. Here the length of the fabric that will bend under its own weight to a definite extent is called bending length. It is a measure of stiffness that determines draping quality. The calculation is as follows.

Three specimens in warp way and three in weft are usually tested and since the relative humidity can affect the results the test should be made in a standard testing atmosphere. The horizontal platform of the instrument is supported by two side pieces made of plastic. These side pieces have engraved on them index lines at the standard angle of deflection of, at which angle. Attached to the instrument is a mirror which enables the operator to view both index lines from a convenient position. The scale of the instrument is graduated in centimeters of bending length and it also serves as the template for cutting the specimens to size.

Apparatus:

  1. Stiffness tester.
  2. Scissor.
  3. Scale.

Sample:

Cotton woven fabric, Size: 6” ×1”.

Atmospheric condition:

  1. Wet condition: –   26 ° c. & Dry condition: – 30° c.
  2. Difference between wet and dry bulb = 30° c-26 ° c.  = 4° c
  3. So, relative humidity (RH) = 70 %

Procedure:

To carry out a test the specimen is cut to size 6” ×1” with the aid of the template. Both the template and specimen are transferred to the platform with the fabric underneath. Now both are slowly pushed forward. The strip of the fabric will commence to drop over the edge of the platform and the movement of the template and the fabric is continued until the tip of the specimen viewed in the mirror cuts both index lines. The bending length can immediately be read off from the scale mark opposite a zero line engraved on the side of the platform. Each specimen is tested four times, at each end and again with the strip turned over. In this way three samples are tested. Finally mean values for the bending length in warp and weft directions can be calculated.

Data:

Serial Number                Warp (CMS)                   Weft (CMS)
  Right Left   Mean Right Left Mean
 1    Face 2.10 2.15  

 

2.66

2.00 2.39  

 

2.51

   Back 2.25 2.25 2.68 2.75
 2    Face 3.10 3.15 2.40 2.20
   Back 2.89 2.97 2.75 2.90
 3    Face 2.50 2.89 2.20 2.25
   Back 2.75 2.95 2.71 2.85

 

Result:

  1. The bending length of the fabric in warp way is 2.66 CMS.
  2. The bending length of the fabric in weft way is 2.51 CMS.

Remarks:

If the bending length of the fabric is more than fabric stiffness is more and if less stiffness is less. From the experiment we see that the bending length of the given fabric is average both in warp and weft way. So the stiffness of the sample fabric is average.

Conclusion:

Stiffness is an important property of fabric for different end uses. This behavior can be imparted fabric by different finishes. We acquire the knowledge about how to find the bending length of the fabric both in warp and weft way. And we also examine the stiffness property of the given sample. This practical will help us in our study life as well as job life. Especial thanks to our teacher and his assistants for great co-operation.

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