a-jour warp knitted fabirc.pdf

8/16/2019 A-Jour Warp Knitted Fabirc.pdf

1/21

Spatial A-Jour knitted Structure

Specialty Knitting(After Mid)

National Textile University,Faisalabad


2/21

What are they???

• Spatial refers to “space”

•

Those knitted structures which contains space

2


3/21

Introduction

• These spatial products are manufactured inthe form distance knitted fabrics built of twoexternal layers and one internal layer

•

These fabrics are next stage of spacer fabrics

3


4/21

Manufacturing• Made on warp knitting machine• Having two or more needle bars• Thickness or space depends upon distance between

needle bars• Its external layers are of plain warp knit stitches• Internal layers have threads or multifilament yarns and

connecting link of the opposite loops of external layersof distance knitted fabrics’ stitches.

• The thickness of the external layers depends on thelinear density of threads used, as well as on thenumber of component stitches.

4


5/21

Manufacturing

• The internal layer is formed by introducing threadsbetween the external walls, therefore the numberof opposite arrangements of external layers

determines the maximum number of threadconfigurations of the internal layer.

• The inner layer may also be formed as only oneconfiguration of threads. There is also a possibilitythat in both arrangements, the I- I ‘and II -II’, threadsare not introduced to the internal layer.

5


6/21

Knitting concept with 4 needle bars

6


7/21

Geometry of fabrics

• The geometry of the knitted solid is strictlydefined by the number of external layers.

• Two different structures can be distinguishedin the construction of spatial knitted products:“open” and “closed”

7


8/21

8


9/21

Distance and Spatial warp knitting

9


10/21

Geometry of fabrics

• Spatial knitted solids can have basicgeometrical figures with triangles, tetragonsor polygons of their cross section or base.

• They may also take the form of more complexfigures, creating solids in the form of spatialreliefs and elements like channel bars, T-barsor double T-bars, Triangular Cross sections, C-bar, Solid in the form of spatial arc.

10


11/21

Geometry of fabrics

Spatial warp-knitted fabrics in the form ofregular prisms similar to a cylinder and spatialarc can be produced.

• Spatial warp-knitted structures are currentlymanufactured on new, multi-needle combwarp knitting machines.

•

There are two types of such warp-knittingmachines those with an even number ofneedle combs and those with an odd number

11


12/21

Geometry of fabrics

• Additionally, the machines are equipped withindividually controlled needle boards whichclose the edges of the spatial knitted fabricsformed.

• The warp knitting machines are also equippedwith a take-up device, which does not deformthe ready-made product when receiving it

12


13/21

Modelling

• Hi-tech computer software ProCAD warpknitt 5is used for modelling the spatial architecture ofexternal and internal layers of a knitted solid.

13


14/21

Novelty in Fabrics

• They are made in two or more regular or irregularexternal layers & having at least one internal layer

14


15/21

Cont.

• The external layers are built of warp knittedplain stitch fabrics.

• Whereas the internal layer consists of threadsegments running between the externallayers.

15


16/21

Property

• In Spatial fabrics, the free spaces created not onlydecrease the mass of the product but are alsotechnological openings through which, for example,

electric wiring can be led in the building beam

16


17/21

Cont …

• An a-jour structure guarantees a small massand low coefficient of the volumetric feelingof the internal layers, therefore less rawmaterial is used than in the case of fully filledstructures

17


18/21


19/21

Engineered Properties

19


20/21

Application

• After being hardened the composites of spatialfabrics are used as ready made composite forbuilding and industry

• Frameworks can be made as elements of machines and devices.

• Spatial reinforcement for fibrous composites,applied in lightweight yet high-strengthengineering structures of various types

20


21/21

a-jour warp knitted fabirc.pdf

Documents