Analyzing on Geometry Design and Tightness of Ramie Fabric

Yi Weng1,a , Lijun Li1,b, Fengfang Li1,c

1Zhejiang Textile & Fashion College，Ningbo, 315211 China

a wengyi@zjff.net, b ccl8325@yahoo.com.cn, c lifenfang@nbip.net

Keywords: ramie fabric; geometry structure; scratchiness; application of fabric tightness domain.

Abstract. The scratchiness of ramie fabric, to some extent, restricts the development of ramie

products, although it has been improved of the underwear ramie fabric to a certain degree, however,

it is at the cost of sacrificing the unique style of ramie fabric. How to keep the special style of ramie

fabric and eliminate scratchiness in the meantime is yet to be solved. This study analyzed the causes

for scratchiness, discussed how to choose the fabric’s geometry, density and tightness, and

established a theoretical formula for the geometric structure of non-tight structure ramie fabric, as

well as warp and weft density and tightness, further more, the study proposed a structural phase

range and maximum weave tightness to overcome the ramie fabric’s scratchiness. All of these

offered the theoretical basis for ramie fabric design.

Introduction

Ramie fiber has the properties of hygroscopic, antiseptic and antibacterial. Nowadays, more and

more people advocate nature and comfort, as a result, various types of ramie textile products have

been developed, which won the favorite of consumers. However, some of ramie fabrics produced

scratchiness, which greatly restricted its further development in the clothing fabrics field, especially

in high-grade of light and comfortable fabrics. Some technical measures such as biological enzyme

soft process can improve ramie fabric scratchiness to some extent, however, as the causes of

scratchiness is complex, the problem of ramie fabric scratchiness has not yet been resolved

thoroughly[1,2].

Ramie fiber is of high rigidity, and when subjected to mechanical actions such as tension,

bending and shear, it will cause stress concentration, so that the microfibril of ramie fiber will

fracture. The fracture point section of the ramie fiber microfibril is acute and rigid. When the

sensory nerve endings in the skin are stimulated by these sharp sections to certain intensity, the

nerve endings will generate excitement and scratchiness. Therefore, the fracture of microfibril under

the mechanical action is the main reason of scratchiness.

This study starts from the ramie fabric texture structure design, and make researches on the

weave density to provide a reasonable theoretical basis for further improve the ramie fabric prickle

and rational design of ramie products.

Analysis on the Geometric Construction and Weaving Density of Ramie Fiber

The deformation analysis on ramie fiber. According to the theories of textile materials, the up and

down cross banding of warp and weft yarn makes it bend. During the bending deformation process,

the outboard elongate after tension, and the inner side shorten after compression. The larger the

bending rate, the smaller the radius of curvature r0, and the larger the deformation variation between

Advanced Materials Research Vols. 175-176 (2011) pp 534-538Online available since 2011/Jan/20 at www.scientific.net© (2011) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.175-176.534

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each layer. When the fiber of outer layer elongates to a certain extent, it will be torn broken.

Therefore, to insure the fiber not to be fractured, the minimum permitted radius of curvature ro is[3],

ε

dr 50min0 > (1)

romin is the minimum curvature radius allowed for the ramie fiber (mm), ε stands for the ramie

fiber tensile elongation at break (%), d stands for the ramie fiber diameter (mm).

As the ramie fiber get thinner (smaller diameter) and the ramie fiber tensile elongation at break ε

increases, the smaller will be the allowed minimum curvature radius romin，and the fiber and yarn

will be difficult to be fractured, the scratchiness source will be less. From this point of view, there is

close relationship between the fibrous properties and scratchiness.

Analysis on the Ramie Fabric Weaving Density. According to the result of the fabric section,

for non-tight structure fabric, buckling properties of weft and warp yarn are calculated according to

the sinusoid[4].

The buckling wave height y0 of warp and weft yarn buckling state curve is: y0=h/2；the buckling

wave length is: x0=l，so

l

xhy

πsin

2×= (2)

Derivation twice, by mathematical operation, the minimum curvature radius r min of buckling

state curve is

2

maxmin )/()/2(/1 πlhKr ×== (3)

rmin is the minimum curvature radius(mm) of buckling state curve; h stands for the yarn buckling

wave height (mm); l stands for the yarn buckling wave length (mm). The warp and weft yarn

interweave to form a buckling wave, so the yarn buckling wave length l = 100 / M,

so

])([)102( 24

min Mhr π×÷×= (4)

M - fabric density (/10 ㎝).

When the yarn buckling wave height h is equal to the warp maximum buckling wave height hjmax,

and the fabric yarn density M is equal to the maximum weft yarn density Mwmax, then the warp yarn

buckling has a minimum curvature radius rjmin; when the yarn buckling wave height h is equal to the

weft yarn maximum buckling wave height hwmax and fabric yarn density M is equal to the maximum

warp density Mjmax, then the weft yarn buckling has the minimum curvature radius rwmin. Therefore,

in ramie fabric designing, in order to make sure ramie fiber not to be broken, then

επ

dMhr wjj 50])([)102( 2

maxmax

4

min ≥×÷×= (5)

επ

dMhr jww 50])([)102( 2

maxmax

4

min ≥×÷×= (6)

so

πε ÷×÷×≤2/1

maxmax )]()400[( dhM jw (7)

πε ÷×÷×≤2/1

maxmax )]()400[( dhM wj (8)

From the analysis, in the fabric weaving process, the yarn bending curvature radius r is related to

the fabric buckling wave height h and fabric density M. When the fabric density is fixed, as h

increases, then r decreases. If the yarn buckling wave height h is fixed, then r decreases with the

Advanced Materials Research Vols. 175-176 535

increase of fabric density M.

Analysis on the Ramie Fabric Weaving Tightness. According to the definition of fabric

tightness,

maxmax jjj MDE ×= (9)

maxmax www MDE ×= (10)

)100( maxmaxmaxmaxmax ÷×−+= wjwjz EEEEE (11)

Ejmax- maximum warp-wise tightness of ramie fabric (%),

Ewmax- maximum weft tightness of ramie fabric (%),

Ezmax- maximum total tightness of ramie fabric (%),

Dj - warp yarn diameter (cm),

Dw - weft yarn diameter (cm).

Use formula (7),(8)to substitute (9)，(10)，(11)，then

)()(2/1

maxmax π×÷×= jjj hADE (12)

)()(2/1

maxmax π×÷×= www hADE ( 1 3 )

])()100/([)( 2/1

maxmaxmaxmaxmax wjwjwwjjz hhADDhDhDAE ××××−×+××÷= ππ (14)

In the formula, 2/1

maxmax )](400[ wj hhdA ××÷×= ε

If D= Dj = Dw h= hj = hw；

Then

]1002[)( 2/1

max ππ ÷×−×÷×= hDhDAEz (15)

The Relationship between Fabric Geometric Structure and Weaving Tightness. According

to (12) (13) (14), the maximum weft and warp yarn tightness of ramie fabric are related with the

warp and weft yarn buckling wave height hj, hw and ramie yarn thickness. Meanwhile, the warp

yarn buckling wave height hj and weft buckling wave height hw mainly depend on the fabric

geometrical structure.

According to Table 1, raw materials are used to spin (Yarn Number: 28tex) and analysis on the

plain weave fabric are shown below

The maximum density variation curve of warp and weft are shown in Fig. 1 and Fig. 2.

The fabric tightness variation curve are shown in Fig. 3, Fig. 4 and Fig. 5.

Table 1 Properties of Ramie Fiber

Item Average fineness

（tex）

Average length

（mm）

Intensity

（cN/dtex）

Elongation at

break（%）

ramie 0.63 89 7.1 2.6

According to the Fig. 1, Fig. 2, Fig.3, Fig.4 and Fig.5, if 28tex ramie yarn is used to design the

plain fabric, the overall tightness of the fabric will be minimum with the fifth structure phase.

In the process of Ramie fabric design, if the ramie fabric tightness is less than the maximum warp

and weft weaving tightness and total tightness, then the bending and scratchiness of fibers and yarns

536 Silk

Fig.1 the Maximum Weft Density can be Woven Theoretically

Fig. 2 The Maximum Warp Density can be Woven

Fig.3 The Maximum Weft Tightness can be Woven

Fig.4 The Maximum Warp Tightness can be Woven

0

20

40

60

80

100

120

0 L/8 L/4 3L/8 L/2 5L/8 3L/4 7L/8 L

weft buckling wave height(mm)

war

p t

igh

tnes

s(%

)

0

20

40

60

80

100

120

0 L/8 L/4 3L/8 L/2 5L/8 3L/4 7L/8 L

weft buckling wave height(mm)

war

p t

ightn

ess(

%)

0

20

40

60

80

100

120

0 L/8 L/4 3L/8 L/2 5L/8 3L/4 7L/8 L

weft buckling wave height(mm)

war

p t

ightn

ess(

%)

0

20

40

60

80

100

120

0 L/8 L/4 3L/8 L/2 5L/8 3L/4 7L/8 L

warp yarn buckling wave height(mm)

wef

t ti

gh

tnes

s(%

)

Advanced Materials Research Vols. 175-176 537

Fig. 5 The Maximum Total Tightness can be Woven

can be reduced. In conclusion, the ramie fabric warp and weft density and tightness should be set

reasonably according to the different raw materials, texture, special parameters and so on.

Meanwhile, to select the appropriate fabric structure phase and to control the buckling wave height

of ramie yarn is also an effective way to prevent scratchiness.

Summary

For ramie fabric, warp and weft yarn woven density and tightness are related with the bending

degree of the yarn interwoven. The higher the buckling wave height, the more severe the flexural

deformation, and warp and weft yarn woven density and tightness are smaller, and vice versa. When

the bending buckling wave height curvature radius is smaller than the permitted minimum fracture

resistance curvature radius romin, the ramie fiber will be broken and induces scratchiness. Therefore,

in order to reduce scratchiness, we should choose the warp and weft density and tightness probably,

and select the appropriate fabric structure phase, so as to avoid overbending in the process of

interweave, as a result, prickle will be improved.

Acknowledgements

A Project Supported by Scientific Research Fund of Zhejiang Provincial Education Department

(y200908537).

References

[1] L. Han, WD. Yu, YM. Zhan, et al: Journal of Donghua University, Natural Science. Vol.28(2)

(2002), p. 135

[2] YL. Jiang: Clothing Industry World. p. 57(1994. 12)

[3] H. Zhu, FL. Wu, et al: Textile Material Science．Beijing: China Textile and Apparel Press. p.

351(1994)

[4] HJ. Wu, PF. Zheng, et al : Principles of Fabric Structure Design．Shanghai：Tongji University

Press. p. 110(1990)

0

20

40

60

80

100

120

0 L/8 L/4 3L/8 L/2 5L/8 3L/4 7L/8 L

warp yarn buckling wave height(mm)

tota

l ti

gh

tnes

s(%

)

538 Silk

Silk 10.4028/www.scientific.net/AMR.175-176 Analyzing on Geometry Design and Tightness of Ramie Fabric 10.4028/www.scientific.net/AMR.175-176.534