3. 1.Prediction of the maximum sett (density) of fabric and fabric
dimensions;
2.Find out relationship between geometrical parameters (picks
and ends);
3.Prediction of mechanical properties by combining fabric and
yarn properties;
4.Understanding fabric performance (handle and surface
effect.
INTRODUCTION
The objectives of fabric geometry is to:
Structure of a woven fabric is defined by weave pattern, thread
density, crimp and yarn count
3
4. Jammed structure
A woven fabric in which warp & weft yarns
don’t have mobility within the structure as
they are in intimate contact with each other
are called jammed structure. In such a
structure the warp & weft yarns will have
minimum thread spacing.
8. Jamming Condition of a fabric
• During jamming the straight portion of the
intersecting yarn will vanish so that-
Jamming warp direction Jamming weft direction
l1–Dθ1 = 0 h2 = D(1 –cosθ2)
l1/D = 0 p1= Dsinθ2
So,
h1 = D(1 -cosθ1)
p2= Dsinθ1
9. Jamming both warp & weft direction
D = h1 + h2
D = D(1 -cosθ1) + D(1 –cosθ2)
Cosθ1 +cosθ2 = 1
10. Square Fabric
• A truly square fabric has equal diameter of
both warp & weft, equal spacing, equal crimp
p2= p1 , c1=c2 , h1=h2 , θ1= θ2
D=2d= h1+h2=2*4/3 p √c
√c =3/4 * d/p
11. Square Jammed fabric
For a sq. jammed fabric θ1 =θ2
So,
Cosθ1 +cosθ2 = 1
Cosθ = ½
θ = π/3
p=Dsinθ
&
l=Dθ
12. Racetrack Model
• In the racetrack model, a and b are maximum and minimum diameters of
the cross-section. The fabric parameters with superscript refer to the zone
AB, which is analogous to the circular thread geometry; the parameters
without superscript refer to the racetrack geometry, a repeat of this is
between C and D.
Then the basic equations will be modified as under:
p2’ = p2 – (a2 – b2)
l1’ = l1 – (a2 – b2)
h1 + h2 = B = b1 + b2
Also if both warp and weft threads are jammed,
the relationship becomes
13. Crimp of sq. jammed fabric
• The crimp in fabric is the most important parameter which influences
several fabric properties such as extensibility , thickness , compressibility
and handle. It also decides quantity of yarn required to weave a fabric
during manufacturing.
The crimp of a sq. jammed fabric is about 20.9 %
we know,
Crimp (c) =l/p -1 [p=Dsinθ &l= Dθ ]
= Dθ/Dsinθ -1
= θ/sinθ – 1
= π/3/sin π/3 - 1 [θ = π/3]
=1.209 -1
= .209
So, c % = 20.9 %
14. Cover factor of square jammed fabric
• In fabric, cover is considered as fraction of the total fabric
area covered by the component yarns.
The fractional cover factor (d/p) = 1/√3
1 X n = 1/√3
28 X √N
n/ √N = 16.2
So, cover factor of both warp & weft is 16.2 AC = 2d
k1 = k2 =16.2 AB = d
And Fabric cover factor is 23 So, BC = √3 d
k1 + k2- k1k2/28 = 23 p = √3 d
15. Relation between warp & weft cover factor
• Where β = d2/d1
• For sq. jammed fabric d2 = d1
• So, β = 1
16. Application of jammed fabric
Jammed fabric are closely woven fabric & find
application in water-proof , wind- proof, bullet-
proof requirements.
17. References
• Woven Textiles: Principles, Technologies and
Applications :- Edited by K Gandhi
• Woven Textile Structure: Theory and
Applications :- By B K Behera, P K Hari
