Woven Fabric Structure and Analysis

Last Updated on 11/04/2021

General Discussion on Fabric Structure and Analysis

Bilal Yakubu
Dept. of Textile Science and Technology
Ahmadu Bello University, Zaria, Nigeria
Email: billsurf.net@gmail.com

Introduction:
A woven fabric is formed by the interlacement of two sets of yarn, namely, warp and weft yarns. These yarns are interlaced with one another according to the type of weave or design. Fabric structure and analysis of woven fabric are discussed in this article.

1. Discuss Briefly the Following Weaves

WARP RIBS
Ribs & Cords are plain weaves structures in which considerable difference exist between the warp & the weft threads as regards to thickness, & number of threads per unit space. The term cord is frequently applied to a rib that runs the length of the cloth. These designs are found in unbalanced structures such as canvases & tarpaulin.

This is a plain weave in which two or more picks are inserted in the same shade. To form warp, rib the thick ends always passes over or under two or more, thick or fine pick as shown in fig-1 below & of 2-2 warp rib. Here the plain weave is extended for two picks. It is possible, however to have a 3-1-1-3 warp rib as shown in fig-2 below;

Warp rib weaves are made by running two or more picks together, a shown in Fig-3 This produces pronounced weft-way ribs, the surface of which consists of warp threads. The rib effect is emphasized by the use of a greater number of ends than picks and the insertion of coarser weft yarns. Consequently, the picks tend to lie rather straight with the ends bending round them, thus producing a warp rib structure in which the warp is mainly visible. The advantage of introducing two free weft yarns instead of one coarse yarn is that a broad rib is achieved without greatly increasing the thickness or weight of the cloth.

Since some confusion can arise in the terminology used, it is worthwhile drawing attention particularly to the fact that ‘warp rib’ weaves produce ribs running weft-way.

Rib effects result from extending the plain weave vertically. The weft is thicker causing the warp to bend and form a warp surface rib running from selvedge to selvedge.

• Warp ribs are woven with a high warp sett, in which the ends cover the weft almost entirely.
• The ribs can be emphasized even more strongly by use of alternate slack and tight ends and thick and fine picks.

If the number of inserted picks in each shed opening is identical, warp rib will be designated as regular; in the opposite case, it is designated as irregular warp rib.

Regular warp rib weave:
The numbers of inserted picks in an even shed opening do not exceed 4. Thereby, only three regular warp ribs exist: warp rib 2-2, warp rib 3-3 and warp rib 4-4.

Irregular warp rib weave:
The irregular warp rib can be classified in three ways:

1. The varied warp rib where the number of picks in each shed opening varies periodically.
2. The interrupted warp rib, where grooves are separated by one, two or several picks to only one fine weft.
3. The varied interrupted warp rib that is the combination of the two preceding cases

WEFT RIBS
This is plain weaves in which two or more ends weaves together as one. To form weft, rib the thick picks always pass over or under two or more thick or fine ends. Here the plain weave is extended for two ends as illustrated for 2-2 filling rib & a 3-1-1-3 filling rib below;

Weft rib is the amplification in width of plain weave. If the number of lifted or lowered yarns in each shed opening is identical, weft rib is designated as regular; in the opposite case, it is designated as irregular.

Regular weft rib weave:
The number of yarns lifting or lowering in the even shed does not exceed 4. Therefore, there exist only 3 regular weft ribs: the weft ribs 2-2, 3-3 and 4-4.

Irregular weft rib weave:
As for the warp rib, there are three types of irregular weft ribs:

1. The varied weft rib
2. The interrupted weft rib
3. The varied-interrupted weft rib

Difference between warp rib weave and weft rib weave:
The difference between warp rib weave and weft rib weave are given below:

Complementary weaves:
This structure, with its characteristically intricate patterns, has been used primarily for decorative borders–both on flat weaves and on the skirts of knotted-pile objects. It is not actually an ‘end finish,’ however. In a complementary-weft weave, weft yarns of contrasting colors are used in pairs, and each weft complements the action of the other exactly. If a light weft passes over four warps and under two, its dark-colored companion follows, passing under four warps and over two. The sequences are changed to vary the patterns: some wefts might go over and under 3 warps, or they might go over 5 and under 1, but they are always used in complementary pairs.

All wefts are allowed enough ease to cover the warps completely, making this a weft-faced weave. When only two colors are used, the back and front faces are similar. The interlacement pattern is the same on both; the position of the colors is merely switched. Small X’s, for example, may be light on one face and dark on the other. Typical patterns are very small: little triangles, diamonds and rosettes predominate. The blocky Qashqa’i so-called ‘domino’ border features one of the more complex motifs. Warps of two different colors are set up in two complementary sets that are integral to the structure of the fabric. Unlike supplementary weft, there is no ground cloth on top of which the pattern is created. Each warp has its counterpart on the opposite face of the cloth, and the design is achieved from the two sets of warps interlacing with the weft. The result is a design with the colors in reverse on each face.

2. Explain the Various Methods of Designation of Twill Weave and Give Reasons for the Construction of This:
Twill weaves are constructed upon any given number of threads exceeding two. The interlacing order of threads in the repeat in twills weaves is identical & the diagonal line is formed by advancing this order in step of one in either direction.

Twill weaves can thus be designated by describing the interlacing of the first threads; using the following methods;

1. 2 up; 2 down
2. 2-& -2
3. 2./.2

The third method, however, is the more convenient method. The above methods of designations indicates that on the first two pick the first two picks the first two ends are up & the following two down or that the first end is raised for the first two picks & lowered for the following two.

Thus, for irregular twills the designation might be;

1. 1 up; 3 down; 2 up; 2 down
2. 1-& -3; 2-& – 2
3. 1.2./.3.2

There are basically two reasons for twill construction;

1. They are used for ornamentation purposes.
2. They are constructed for enabling cloth of greater weight; closer settings & better draping quality.

Twill weave are extensively used in manufacturing cloth for garments household cloth and industrial cloth:

1. Generally, Diamond, diaper and zigzag twill are used for making pillow, cover, screen, upholstery, bed sheet, towel etc.
2. Continuous twill are used for making fabric for shirting, suiting and pant in (denim, gaberdine).
3. For making various type of ornamental cloth, other derivatives of twill weave are used.
4. Hearing bone twill are used in the cloth of suiting and overcoats.

3. Explain Briefly the Major Constructional Differences Between Pointed and Herringbone Twill Weave:

Pointed Twill Weave:
It is the simplest and one of the most important modifications of twill weave produced by reversing the direction of twill at suitable interval A point is selected (usually the last warp is selected) as the reversing point and so it is sometime call as point twill. In this twill pointed or straight draft is used. This twill is produced by combining S and Z twist. According to reversing of direction there are two type of zigzag twill:

1. Horizontal zigzag twill.
2. Vertical zigzag twill.

1. Horizontal pointed twill:
When the reversal direction of twill line occurs upon the warp yarn, it results a horizontal zigzag twill, Here the basic twill is extended in warp direction. Here the number of warp yarn in a repeat is double of the number of wefts. In horizontal zigzag twill pointed draft is used.

2. Vertical pointed twill: 
When the reversal direction of twill line occurs upon the weft yarn, it results a vertical zigzag twill, Here the basic twill is extended in weft direction. Here the number of weft yarn in a repeat is double of the number of warps. In Vertical zigzag twill straight draft is used.

Hearing Bone Twill: 
This twill is constructed in a different manner from the ordinary zigzag twill. Though it also depends on reversal of twill direction Here reversal direction occurs after a middle line. Here at first the basic twill is drown then the number of central point is selected in zigzag twill. Rather in extended second half of basic twill the following matter happened.

• The floating point of first half become down in second half.
• The down of first half become floating in second half.

In hearing bone twill straight draft is used. There are two type of hearing bone design

1. Horizontal hearing bone twill.
2. Vertical hearing bone twill.

1. Horizontal hearing bone twill:
When hearing bone twill is created by extending the basic twill in warp direction, horizontal hearing bone result.

2. Vertical hearing bone twill:
When hearing bone twill is created by extending the basic twill in weft direction, horizontal hearing bone result.

4. Explain Fully the Various Reasons for the Construction of Twill Weave:
Twill weave are extensively used in manufacturing cloth for garments household cloth and industrial cloth.

1. Generally, Diamond, diaper and zigzag twill are used for making pillow, cover, screen, upholstery, bed sheet, towel etc.
2. Continuous twill are used for making fabric for shirting, suiting and pant in (denim, gaberdine).
3. For making various type of ornamental cloth, other derivatives of twill weave are used.
4. Hearing bone twill are used in the cloth of suiting and overcoats.

References

1. Textile design & Colors (Seventh Edition) by Watson & Gronski.
2. Woven Cloth Construction; by Robinson & Mark.
3. The American Cotton Handbook volume 2 by Dames S. Hamby.
4. Md. Enamul Haque “Twill Weave: Features, Classification, Derivatives and Uses” (https://textilelearner.net/twill-weave-features-classification-derivatives-and-uses/)

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3. Basic Elements of Woven Fabric Design
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Mazharul Islam Kiron

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

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