Determine Stiffness of the Fabric by Shirley Stiffness Tester

Last Updated on 07/04/2021

Name of the Experiment:
Determine stiffness of the fabric by Shirley stiffness tester

Introduction:
Stiffness is a special property of fabric. It is the tendency of fabric to keep standing without any support. It is a key factor in the study of handle and drape of fabric. The stiffness of a fabric in bending is very dependent on its thickness, the thicker the fabric, the stiffer it is if all other factors remain the same.

Objectives:

To determine the stiffness of the given fabric sample.

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

Figure: Fiber stiffness, cantilever principle

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 he 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 f {41(1/2)^o} = 0.5. 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:

Stiffness Tester
Scissor
Scale

Sample:

Cotton woven fabric
Size: 6 x 1″.

Atmosphere:

Temperature – 25^oC and relative humidity – 67%
Standard atmosphere: temperature – 20^oC and relative humidity – 65%.

Machine specification:

Name: Shirley Stiffness Tester

Shirley Stiffness Tester Working Principle:

To carry out a test the specimen is cut to size 6 in. x 1 in. 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 droop 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:

S/n		Warp (CMS)			Weft (CMS)
		Right	Left	Mean	Right	Left	Mean
1	F	2.1	2.15	2.66	2	2.39	2.51
1	B	2.25	2.25		2.68	2.75
2	F	3.1	3.15		2.4	2.2
2	B	2.89	2.97		2.75	2.9
3	F	2.5	2.89		2.2	2.25
3	B	2.75	2.95		2.71	2.85

Table: Bending length obtained from test

Results:

The bending length of the fabric in warp way is 2.66 cms.
The bending length of the fabric in weft way is is 2.51 cms.

Remark:
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.

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Mazharul Islam Kiron

Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.