Tensile Behaviour of Spun Yarns under Static State - Journal of ...

a case where the interactions actually reduce system
property and I=0 means that the interaction does not
exist, so that the Eq. (13) degenerates in to the simple
ROM. The expression for I can be expressed as Eq.
(14):
I
4X
50%
X 2
2( X 1 X 2 ) 4[ X 50% 0.5( X 1 )]
4 [ X 50 % x ] 4X
(14)
Where, X 50% is the actual system property X s, when the
W 1 = W 2 = 0.5 and x = 0.5 X 1 + 0.5 X 2 are the
arithmetic mean of the property for homogeneous
constituents composed of X 1 and X 2 alone. If there are
no interactions of the two constituents, there will be
X 50% = x, so that X = 0 and I = 0.
Marom, Fischer, Tuler, and Wagner explained that the
alteration of the system’s overall properties caused by
the interaction of the different constituents can be
specified by using the concept of hybrid effect. One
definition of the hybrid effect is given as the deviation
of behavior of hybrid structure from the ROM. A
positive hybrid effect means the synergetic case, and
the actual property is above the ROM prediction, where
as a negative hybrid effect means the property is below
the prediction. Therefore, numerically the value of X
can used to indicate the hybrid effect and can be
written from Eq. (14) as:
X X x X 0.5X
0.5 ) (15)
50%
50% ( 1 X 2
The Eq. (13) can be normalized to eliminate the effect
of twist as follows Eq. (16):
X
sn
X s X 1
I
W1
( 1W1
) W1
(1 W1
) (16)
X X
X
2
2
The more efficient way of normalizing the Eq. (13) to
eliminate the effect of twist to develop the relationship
between relative tenacity and blend ratio is as follows
Eq. (17):
X
X
X
s 1
sn% W1
W
X 50% X 50% X 50%
2
I
( 1
1)
I
( 1W1
)
(17)
X
50%
properties, such as the tensile modulus. The increase in
modulus ratio leads to increase in interaction effect 33 .
Pan, and Postle derived a statistical model for
prediction of blended yarn strength. He explained that
the blended yarn strength y is a statistical variable
with a normal distribution function H ( y)
, which can be
expressed as Eq. (18):
1 ( y
)
H ( y ) exp[
(18)
2
2
y
y
2
y
Where, y is the average strength of blended yarn and
2
y
is the variance of yarn strength. The distribution
parameters can be calculated, according to the statistical
theory as follows Eq. (19) and Eq. (20).
1
E f 2
1
1
y
q V
1 V2
( l
c1
11)
exp (19)
E f 1
1
Where,
2
2 2
E f 2
1
1
y q 2 ( c1
11)
E f 1
V
1 V
l
1
1
exp
.(
a 1 N )
1
1
exp
1
(20)
q
is called the orientation efficiency factor; V 1
& V 2 , fiber volume fractions of type 1 & 2; E f1 and E f2
are the tensile modulus of type 1 & 2 fibers; is the
fiber length;
1
& 1
are the scale & shape parameter of
a 1
fibers respectively; , N are the number proportion of
fiber 1 and total number of fibers respectively.
According to the hypothesis on estimating the
maximum range of statistical distribution, based on this
normality of the strength distribution, there is a 99%
chance that the actual blended yarn strength will fall in
to the range of y 3 y . He also quantified the
strength hybrid effect by a new parameter y , which
predicts the deviation of the actual yarn strength from
the strength predicted by the Rule of Mixture. This can
be expressed as Eq. (21):
l c1
[X 50% include the effect of both twist and interactions],
the model indicated good correlation with the practical
observations. The nature and results of the interactions
of different fiber types are determined by their
l
y
l
c1
f
1
1
(21)
Journal of Engineered Fibers and Fabrics
Volume 5, Issue 1 - 2010
7
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