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Textile hand is related to such

fabric properties as smoothness,

softness, hardness, roughness,

thickness, weight, warmth, sharpness,

rigidity, etc. The most important of them

are considered to be smoothness (28%),

and softness (22%), while the importance

of the rest properties (the total number of

which is 21 [1]) gradually decrease, down

to 0.3%. In the meantime, fabric handleand performance properties change after

their nishing treatment [2,3].

The method of testing fabric by extract-

ing it through the hole of a ring has been

known from old times. Recently, new

textile hand evaluation methods based on

pulling a disc-shaped specimen through a

rounded hole have appeared [4]. Special

attention must be drawn to the works

of the Denkendorf Institute of Textile

Technology ITV (Germany) [5,6], which

present the original ITV-Griff-Tester ap-paratus and describe investigations of the

behaviour of socks and other garments

under pulling test conditions. Analogous

New Method for the Objective Evaluationof Textile Hand

Eugenija Strazdien,Matas Gutauskas

Kaunas University of TechnologyFaculty of Design and Technologies

Studentu str. 56, Kaunas LT-51424, Lithuania,E-mail: eugenija.strazdienija@ktu.lt

AbstractThe investigations presented show that pulling a disc-shaped specimen through the roundedhole can be considered as a perspective test method for textile hand evaluation. It was de-termined that the process of pulling a comparatively big specimen ( 113 mm) through arelatively small hole ( 20-40 mm) ends in the formation of a shell which has a complicatedtime-dependant shape. Under the stand of the test unit, the shell becomes cone-shaped, butabove the stand it obtains the shape of a waved disc, the roughness of which increases withthe decrease in its diameter. The aim of this research was therefore to reveal the applicationpossibilities of pulling the material disc through the round hole for the objective evaluation oftextiles hand, and to investigate the effect of fabric type, its anisotropy level, and the properselection of testing regimes upon the character of the pulling process.

Key words: hand, textile hand evaluation, pulling-through-the-hole-method, disk-shapedspeciman, textile features.

investigations have been performed

at the Kaunas University of Technol-

ogy (Lithuania) [7]. A universal test unit

(KTU-Griff-Tester), operating together

with either the standard tensile testing

machine or an individual drive, has been

created there. It allowed a specimen pull-

ing curve P-H (force-deection) to be

registered, and images of specimen shape

variations to be captured.

The KTU pulling test unit ensures even

changes of distance between the limiting

plates over the scale of 0-25 mm with the

accuracy of 0.05 mm. It has a set of con-

vertible pads and a digital camera, and

can be used to evaluate the hand of al-

most all types of textiles, both traditional

and technical (Figure 1).

At the rst stage of the research per-

formed at the Kaunas University of

Technology, theoretical investigations ofthe process of specimen pulling through

a rounded hole were performed:

three cases of specimen pulling through

a rounded hole were analysed [8];

the conditions of specimen jamming

in the hole of the pad or between the

limiting plates were dened [9];

the regularities of the specimens

outer contour roughness variations

were determined [10].

At the second stage of the research,

experimental investigations of the be-haviour of different textile materials

(woven, knitted and coated fabrics)

were performed, and optimal testing con-

a

b

c

d

e

h

g

f

Figure 1. Specimen KTU-Griff-Testerclamping device [12]; a - the attachment

to the force sensor, b - the indentor guides,c - the indentor, d - the table of the pad,e - the window for specimen, f - the scale forpads height adjustement, g - the supportingplate, h - the needle.

the supportingplate

h

the pad the hole

the specimen

the needle

Figure 2. Principal scheme of textile handevaluation in the pulling process [7].

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Figure 5. The dependency between the pulling height H and the calculated value of radius Rz.

Figure 3. The dependence between the thickness if the material and the value of intermediatespecimens radius , when it starts to jam in the hole of the pad.

Figure 4. The dependence between the /h and the value of intermediate specimens radius, when it starts to jam between the limiting plates.

ditions were selected. Additionally, the

parameters of the pad hole and its edges

were dened. Besides that, the effect of

the materials anisotropy level upon the

shape of the P-H curve and upon the vari-

ations of specimen outer contour rough-

ness was determined [11].

In this presentation, the main results of

the KTUs investigations in the eld of

the complex evaluation of textile hand

are presented; they reveal the applica-

tion possibilities of the method of pulling

material through the round hole for the

objective evaluation of textile hand.

n Test Method

Almost all the parameters of KTU-Griff-

Tester unit match those of other devices

for analogous purposes. The stand is

made of plexiglass while the supporting

plate is made of antireex glass. The

technical characteristics of test unit are

as follows (Figure 2): radius of specimen

- 56.5 mm; number of pads - 5; radiuses

of holes in pads - 7.5, 10, 12.5, 15, 20

mm; radius of the indentor - 5 mm; rateof deformation - 100 mm/min.

The radius rof the pads hole and the dis-

tance h between the limiting plates were

chosen in respect to the thickness of the

tested material:

(1)

and

(2)

The above conditions do not allow the

specimen to jam in either the hole of

the stand (equation 1) or between the

limiting plates (equation 2). The wavy

shape of the specimens outer contour

was dened and predicted, making the

assumption that it can be described as a

sine curve, the length of which is in close

relation with the arc length of a certain

ellipsis [10].

n Results and Discussion

On the basis of equations 1 and 2 optimal

testing conditions were chosen. Accord-

ing to these equations, the relationship

between the two parameters and

on one hand and specimens thickness

and ratio /hon the other were deter-

mined by showing the limits where the

specimen (R=56.5 mm) does not jam in

either the hole of the pad (Figure 3) or

between the limiting plates (Figure 4).The optimal radiuses (in millimetres) of

the pads hole for the material not to be

jammed are as follows:

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Figure 6.Typical pulling curves of knittedmaterials: a) when h=5.5; b) h=const=2 mm.

r= 7.5 mm, when 0.0

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a) b)

The sum of the above-mentioned criteria

(Figure 9) sufciently well characterisesthose material properties (smoothness,

softness, hardness, roughness, thickness,

weight, etc.), which are considered to be

related to fabric hand. For the determina-

tion of these criteria, a thickness gauge,

scales and a KTU-Griff-Tester test unit

are needed. The analysis of criteria and

the optimisation of their quantity and

structure is still ongoing. In the future the

quantity of criteria may be different.

The test data has proved that all the

mentioned criteria are reliable. This datastates that all six materials have a range

of hand degradation as follows: V (1.0)

- M(1.8) - R(2.4) - G-2(2.5) - G-1(3.4).

Figure 8. Typical shapes of specimens pulled through a rounded hole; a) knitted material,b) woven material .

Figure 9. Optimisation diagram of six different materials on the basis of the complex handcriterion.

Received 10.08.2004 Reviewed 01.02.2005

A comparative analysis of diagram areas

has shown that fabric V is better than the

rest by 1.8-3.4 times.

n Conclusions

The absolute values of the measured

P and H parameters are signicantly

affected by the quality of the holes

edges (chamfer angle and cleanness).

The anisotropy level of the mate-

rial tested greatly inuences not

only the shape of the HPcurve but

also the geometry of the deformed(i.e. pulled) specimen.

The selection of optimal testing condi-

tions must be carried out in respect to

the thickness of specimen, i.e. the r

and h values must be chosen accord-

ing to the value, e.g., and

h/= const.

A more qualitative evaluation of tex-

tile hand can be made on the basis of

the complex of criteria, the majority

of which are obtained in the pullingprocess.

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