The use of Recent Developments in conventional Weaving &
Shedding technology to create 3D one piece woven Carbon Preforms
Christopher McHugh
Sigmatex
Manor Farm Road
Runcorn, Cheshire WA71TE
ABSTRACT
The main objective of this paper is to demonstrate how 3 Dimensional Carbon fabrics can be
commercially manufactured using current design and manufacturing methods. Many fabric
forming methods exist to manufacture 3Dimensional structures, each with their own advantages.
Bespoke machines have been developed to lay fibers in 3 or more directions and are keen to be
called true 3D Weaving machines [1]. Other methods of creating 3D composites also have been
widely publicized including Multi-axial Fiber tow laying, Braiding, Knitting and Non-Woven,
however the inherent processing methods also have their limitations when processing Carbon
Fiber. During the course of this paper items for discussion will include the need for a range of
products to be developed without the need for many specialist fabric forming methods. By using
conventional machinery it is possible to move to the next level of composite manufacture by
creating One Piece Woven structures. These structures can be transported easily then expanded
to create many forms, eliminating the need for multiple layup of Carbon Fibers.
1. INTRODUCTION
Whilst 3D woven materials have been available for many years, the processing of Carbon Fiber
as a 3D woven structure has been limited. Conventionally, single layers of Carbon fabrics have
been bonded together to form various 3D structures, however the designs available for this
method of fabric forming have been limited using examples as Plain, Twill and Satin variants.
With recent developments in weaving technologies, carbon fiber processing has improved
substantially and allowed the manufacture of 3D structures in various forms to be produced.
During the course of this paper design methods will be illustrated for the different 3D structures,
with discussions surrounding the inherent characteristics of the fabric constructions and process
benefits. The Fabric forming process will be also discussed and include the use of state of the art
technology to assist in the fiber control as part of the primary weaving functions.
1.1 Purpose
Throughout the composites industry carbon fiber is used or can be used to improve the
functionality of the finished component. Most end users will see the material enter their process
already woven with resin pre-impregnated and ready to be laid up to form the required
component. This process of taking one or many layers of flat woven material and forming a
structure can be very time consuming and costly however by controlling the carbon fiber yarns
during weaving, their placement within a structure can be accurately achieved. By demonstrating
I hereby license SAMPE to publish this paper and to use it for all SAMPE’s current and future
publication uses. Copyright 2009 by Sigmatex. Published by Society for the Advancement of
Material and Process Engineering with permission.
the possibilities achievable using current manufacturing methods, the acceptance of 3D
structures will become more widespread within the composites industry. Although there are
obstacles to overcome, there are many opportunities and possibilities for 3D woven applications.
2. FABRIC FORMING
The weaving process consists of many different functions, and whilst these functions have the
same definition when weaving 2D and 3D fabrics, the method used to achieve each function can
be very different. This is especially true when weaving 3D structures. Primary functions include
Shedding, Pick Insertion & Beat-up with secondary consisting of Warp Control and Fabric Take
up. Another important factor and one becoming more essential is the Design Process. When
considering weaving One Piece Woven 3D structures, design is an essential function, influencing
many material properties and controlling weaving machine parameters.
2.1 Shedding
The Shedding function is usually achieved by using crank, cam, dobby and Jacquard, whilst
Multiphase weaving systems are also available for weaving high volume simple fabrics [2]. Each
different method is used to separate the warp threads in such a manner that the weft pick can be
inserted clearly, without interference from fibers or threads. To enable the maximum possible
range of opportunities it is necessary to use Jacquard shedding technology. Simple Jacquards use
mechanical systems to lift harness cords connected to springs. Between the spring and harness
cord are heddles, through which the fibers are drawn. By connecting each of these harness cords
to its own lifting unit, single thread control is possible. The Shedding possibilities have been
improved substantially over recent years and new advances allow even more thread control to be
possible. For the purpose of weaving a range of 3D structures, single end jacquard control is
essential for maximum flexibility.
2.2 Pick Insertion and Beat up
Pick or Filling insertion is the method used to insert the 90 degree fiber into the structure. This
can be achieved in several ways including Water Jet, Air Jet, Projectile, Shuttle and Rapier
systems. The type of fiber requiring insertion will however dictate the suitability of the insertion
method. The positive action of the Rapier method allows more accurate fiber tow placement and
is more suited to Carbon Fiber Filling insertion. The Beat-up function is performed by a reed
which is used to beat the inserted filling into the fell of the fabric during shed crossing.
2.3 Warp Control
When weaving 3D structures, warp control ensures the fiber tows are delivered under the
optimum tension. When considering weaving Orthogonal or Angle Interlock structures with
different Z binder configurations, standard warp delivery is unsuitable. Each of the Binder
threads requires individual control within the structure. Again this can be achieved during the
design process.
2.4 Fabric Take up
The method of delivering the woven fabric from the beat up position is controlled by the Take up
system. Take up is measured by pick density or picks per unit length. When weaving 2D fabrics
the rate of take up is usually constant, however 3D structures can require multiple pick densities.
In order to achieve maximum control of this function it is important to control it within the
electronic design of the structure. This enables pick rate to be changed for each pick inserted and
can have a great influence on the dimensioning of One Piece Woven 3D components. When
weaving multiple layers of fabric the take up should not contain tight radii, to prevent
manipulation of the internal fiber structure.
2.5 Design
The 3D design process for technical applications requires greater understanding of the weaving
process and loom functions. The weave designs used to create 3D structures can be very complex
and unlike plain weave 2D weave repeats of 2 ends and 2 picks, can repeat over hundreds of
ends and picks. When considering weaving component structures the yarn paths have to be
considered in 3 planes. The CAD design is also used to program certain loom parameters and
Jacquard functions.
3. CLASSIFICATION OF 3D WOVEN STRUCTURES
3D woven structures have been classified as Solid, Shell, Hollow and Nodal [3], each very
different in appearance and construction, however most 3D woven structures will fall into one of
these categories. Constant Cross Section 3D structures can be added to this list and 3D
component structures, where a product is woven to specific dimensions and may involve a
design containing multiple 3D structural elements.
3.1 Solid 3D Woven Structures
This type of structure is constructed using multiple Layers of stuffer warps and wefts, combined
with a through thickness binder. The way by which the through thickness binder links the layers
within the structure, determines the definition of the weave design. These structures can be
manufactured using well known 3D weaving techniques [4], whilst also woven using
conventional methods [5]. More complex solid structures are possible by using a Ply Drop Off
method, where the solid structure is tapered by reducing the amount of layers of warp and weft.
Although it is possible to weave these structures on single sided weft insertion systems, excess
threads need to be removed to achieve the taper.
3.2 Shell Structures
Typically this type of structure is created by changing the weave style combined with differential
let off and take up mechanisms. This combination of technology and design allows greater
formability of the finished product. Bespoke machinery is available for creating this type of 3D
shell [6], which is well publicized.
3.3 Hollow Structures
This type of structure is one where the material is woven as a relatively flat fabric and opened
out to form a more voluminous structure. Spacer fabrics using multi-beam technology can also
be classified as hollow structures where the length of the binding thread between layers
determines the expandable depth. Recent work has been carried out on honeycomb structures
woven using cotton to demonstrate the 3D effect [7].
3.3.1 Cellular
Cellular structures can take the form of honeycombs in warp, weft or both directions. The
distance between the outer structure surfaces is determined by the combination of fabric sett and
internal structure weave repeat size. Figure 1 shows Honeycombs A & B with different tether
lengths T1 & T2, the greater the tether length the greater the depth achieved between outer
profiles. The interface between the layers and the weave construction used at the layer
interlacing points within the structure will also have an impact on end use performance.
Figure 1. Different Depths of Honeycombs
3.3.2 Tapered Cellular
When creating expandable structures, the distance between the outer layers can be changed by
altering the length of the internal tethers T1 & T2 through the design as seen in Figure 2. The
contoured effect will be achieved by combining multiple layers of hexagonal elements and by
reducing the tether length to reduce depth or increase length to increase outer profile distance.
Figure 2. Combined depths to achieve Tapered Honeycomb structure
3.4 Constant Cross Section
These structures are can be woven in both warp or weft directions and have a defined cross
section which remains continuous throughout the structure. The structure in Figure 3 and Figure
4 are examples of a constant cross section profile, where the product is woven as a flat structure
with the required thread separation to form the desired cross section.
Figure 3. Carbon Fiber I Beam
Figure 4. Carbon Fiber Pi section
3.5 3D Component Structures
A 3D Component structure uses a combination of weave and design elements to form a
component of the required dimension. The component structure can contain a number of the 3D
elements already outlined which when combined form a component part. Although further work
will be required to machine the part, the inherent structure is woven in one piece. Component
structures can be created with different profiles and designed to specific dimensions with the use
of design protocols and weave CAD software. By importing the image of the component directly
into weave CAD software, different areas within the design are allocated different weave
structures to provide the required 3 Dimensional geometry.
4. WEAVING AND SHEDDING TECHNOLOGY
For the purpose of this work the main focus will be how the combination of weaving design and
shedding technology allows the weaving of complex 3D woven Carbon Fiber structures. All the
structures woven for this work used Standard Modulus 12K Carbon fiber in both the warp and
the weft directions. Machine information is shown in Table 1.
Table 1. Loom and Jacquard type Loom Type
Control Panel
Jacquard Type
Controller
Dornier PTS 1/J Rapier Loom 1.5M
weaving width
Dialog Panel 2
Staubli Unival 100
Type JC6U 100
4.1 Carbon Fiber Properties affecting Weaving Functions
Carbon fiber composites rely on the carbon content to provide the strength associated with the
structures. Any processing which affects the carbon fiber strength will ultimately have an impact
on the strength of the finished application. This is particularly relevant for 3D structures where a
greater mass of filaments are processed. The Carbon Fiber used for this application has an
elongation of 1.8%, as such it is very difficult to weave when compared with other higher
elongation fibers. This is due to the opening of the fiber mass when shedding occurs, as
illustrated in Figure 5.
Figure 5. Thread separation as shedding opens for pick insertion
Another prohibitive property of the Carbon Fiber is the compressive strength and lack of
resistance to abrasion during the weaving process. During weaving, Carbon warp threads pass
through guides, warp delivery systems, heddles and reed. As the fiber contacts these weaving
components it is abraded resulting in fiber and fabric damage.
4.2 Loom Setup
For the purpose of the weaving trial, the warp was delivered from a separate creel and fed to the
loom at a minimum tension. The thread paths were determined by the use of yarn guides and a
roller mechanism at the rear of the loom to ensure minimal fiber to fiber contact. The warp yarns
were then fed into the Jacquard heddles and drawn 2 threads per heddle at a total warp density of
32ends/cm. The loom pick rate varied according to the design being woven. The Jacquard has
5000 hook capability with harness of 35.46hooks/cm at a weaving width of 141cm.
4.3 Jacquard Function
By using Jacquard shedding mechanisms with individual thread control, each Carbon Fiber can
be positioned at any location in a multilayer assembly. The jacquard was setup to weave 2X12k
per heddle to maximize the carbon content of the structure. 18 hooks/cm were used resulting in
17.46 hooks/cm being unused or cast out. By drawing in the threads in this way greater
consolidation of fiber was possible. The Unival 100 uses actuators to lift the thread as opposed to
electro-magnetic jacquard and hook and knife methods. Each hook is controlled individually to
maximize the design and shedding capabilities.
5. EXPERIMENTAL WEAVING TRIAL
The first weaving trial used a 9 warp layer Angle Interlock design with a weaving sett of 32 body
ends/cm, 2binder ends/cm and 32picks/cm. The Angle Interlock structure was designed with
through thickness binding to provide a surface characteristic shown in Figure 6. Each weft stack
was 9 layers thick and the binder was stepped to provide even through thickness binding. The
loom speed was set at 70picks/minute.
Figure 6. Binder surfacing Repeat
Shed geometry was set to ensure upper and lower shed displacement was equal reducing
variation in warp extension. Although the procedure of offsetting shed height is common
throughout weaving to promote high density fabrics, the procedure is not suitable for Carbon
Fiber weaving.
5.1 Weaving Trial Results
After weaving for 10cm, excess filamentation was evident between reed and harness as seen in
Figure 7.
Figure 7. Broken Filaments during weaving
Due to the location of the filamentation, the fiber degradation must have been caused by the fiber
passing through the harness, as no filamentation was evident between the warp creel and rear of
jacquard harness. Due to the nature of the weave structure, the stuffer threads remain in an upper
or lower dwell period during 33 pick insertions, depending on their position within the design.
The Fabric take up is pulling the fiber through the heddle which could account for the fiber
degradation evident. A trial was conducted to examine the effect on filamentation when a
contoured close shed profile was used.
5.1.1 Close Shed Profile Changes to Reduce Filamentation
Figure 8 shows the Open shed profile of the Jacquard during 1 machine cycle. The blue line
shows the Close shed profile and the green line shows the shed crossing profile. The shed
crossing profile is the profile followed by the heddles crossing from upper shed position to lower
shed position during the weaving cycle. The close shed profile indicates that the heddles remain
in the upper or lower position until a shed change is required.
Figure 8. Flat close shed profile
To reduce the drag and abrasion on the Carbon threads the Close shed profile was configured to
provide a more continuous movement as the threads pass through the harness. Figure 9 shows the
close shed profile and the hook movement through a machine cycle. The crossing shed profile
remains the same opening by 87% at 60 degrees of machine rotation in both flat and contoured
shed profiles.
Figure 9. Contoured Close shed profile
The structure was then woven and the reduction in filamentation was clearly evident as seen in
Figure 10 below.
Figure 10 – Clear warp sheet after profile change
By having the ability to control the shed geometry in this way it is evident that the ability to
weave Carbon Fiber has been improved.
5.1.2 Tension Peaks within Multilayer 3D Structures
One of the main concerns when manufacturing multiple layer structures is the need to ensure the
non-visible yarns within the structure are woven in the correct location. Although design
software is readily available to check the weave design itself, thread placement errors due to
Material or machine fault are impossible to identify. Obstructions caused by broken filaments or
tight warp threads can result in misplacement of threads in both warp and weft directions. The
Unival jacquard monitors the torque required to lift the Warp ends and if the amount is excessive
the jacquard will stop the loom and identify the location of the problem thread. Figure 11 shows
the percentage of Maximum torque used by the actuator to lift the thread when a tight thread is
evident. The red lines indicate the highest loads identified, green indicate the average torque for
the top 10 highest loads and the blue is the total average load. A load at 120% peak in required
torque causes the loom to stop and the faulty thread is lifted automatically for repair.
Figure 11 – Peak loading caused by tight thread
This method of fault prevention is a necessary step toward identifying problems in thread
placement through a 3D structure.
6. WEAVE DESIGN METHOD FOR TAPERED EXPANDABLE ONE
PIECE WOVEN STRUCTURE
The Design process is continuously evolving for complex Technical structures. Different Weave
CAD providers offer solutions to assist in the development and design of 3D structures and will
tailor the software to suit the application. Examples commercially available including ScotCAD,
EAT and TexEng. For the purpose of this work Ned Graphics CAD was used to program the
jacquard. The method of design for 3D structures varies and is dependent on dimensioning
requirements, weaving method and type of structure required. A typical Design Process flow for
a One Piece Woven design is illustrated in Figure 12.
Figure 12. Design Flow
6.1 Structure Definition
The material specification requirements need to be determined to ensure the correct fiber tows
are allocated to the correct layer of the structure. For this example a plain weave construction
was used within a honeycomb structure. The Honeycomb definition is identified by the layer
configuration of the structure. In this instance the Honeycomb geometry is defined as a 4-8-5-8-4
configuration, hence the fabric was woven 4 layers deep splitting to 8 layers, 5 layers, 8 layers
and back to 4 layers as seen in Figure 13. For this structure the pick rate was 16picks/cm in total,
distributed throughout each layer.
Figure 13 - Shape Configuration Geometry 6.2 Design Protocol
Sett data in the form of threads per cm in warp and weft directions is transferred into linear
dimensions. For dimensioned parts, finished customer geometry is converted to the weave design
using sett data. The crimp associated with each weave can also be used to calculate the
shrinkages and finished sett data which will allow more accurate dimensioning of One Piece
Woven structures. The weave design can be manipulated to compensate for the differences in
sett at each level if required. For the purpose of this trial the protocol will reflect the dimensions
of the flat structure with the sett data changing at each depth zone.
6.3 Weave Creation
The finished product requires threads to be in predetermined locations in defined weave styles.
For the purpose of this design multiple areas with different weave styles were used to create the
tapered structure. The primary concern when creating this type of multi-weave structure is the
repeating length of each of the weave styles and the continuity of thread path. The design was
split into 25 separate weave zones with 5 design repeat sections containing 3 weave designs, one
for each of the depth zones. By increasing the number of weave repeats within each depth zone,
a greater depth is achieved whilst ensuring thread path continuity.
6.4 Design Import and Modification
The design was created so that each weave zone was a multiple of the weave pick repeat. Figure
14 shows the 25 separate weave zones, each containing a defined number of picks in the vertical
direction to match the weaves used. The different colors are then assigned to a weave and CAD
software used to create a JC6 file output for the Jacquard. When there is a requirement to
increase the pick density at a certain point in the design, the design is manipulated by stretching
or shrinking the zones to ensure the correct dimensions are achieved.
Figure 14 - Weave Zones
6.5 Design Export
The Weave Design Software uses multiple programs which are used to ensure the design input
matches the required output. The process includes input of warp and weft data, weave allocation
to specific colored design areas and linking all the data into a machine readable format. In this
instance the output file is .JC6 format. When all parameters have been entered into the design the
JC6 file containing the Jacquard lift information is loaded into the jacquard either by USB or via
Network.
7. WEAVING RESULTS OF THE ONE PIECE EXPANDABLE
STRUCTURE
By using the improved close shed methods of weaving combined with the method of linking the
individual weave styles, a design was created and woven. When removed from loom the
structure was mounted between two composite materials then force was applied to separate the
structure and separate the layers. Figure 15 is an image of the structure demonstrating the type of
shape that can be achieved with this method of weaving 3D expandable structures.
Figure 15 – Tapered Carbon Fiber Honeycomb structure
The image shown in Figure 16 shows the split zone where the 4 layer zone split to 8 layers.
Whilst the depth achieved by using this method tapered from 0mm to 90mm, theoretically any
depth could be achieved when the cells are woven in the warp direction up to the length of the
warp threads in the creel. When woven in the weft direction the limitation on depth would be
dictated by the width of the loom and jacquard constraints.
Figure 16 – Close up of Split zone
The image shown in Figure 17 shows a Carbon Fiber structure woven using the same method but
increasing the repeat lengths of the depth zones. When expanded the structure had a depth
between the outer layers of 600mm, without a taper.
Figure 17 Woven Carbon Fiber Honeycomb structure
8. DISCUSSIONS AND CONCLUSIONS
The possibility to weave component structures and supply direct to the component manufacturers
for resin infusion and assembly is very attractive. By creating One Piece Woven structures as
demonstrated, the outer layers are linked by an internal fiber weave eliminating the need for
internal joining and laying up. The shedding technology used has been shown to improve the
process of converting Carbon Fiber into a three dimensional structure whilst monitoring for tight
ends and weave faults. Although production rates will be low compared to weaving conventional
textile fibers, loom output will be offset by improved material properties and reduced component
manufacturing times. Improvements in material performance could also be realized by
combining alternative fibers and weave styles into the One Piece Woven Structure. However,
this method of creating structures requires development and investments in new resin
technology. Whilst some work has been carried out on impregnating hexagonal structures [7],
the commercialization of a resin infusion system needs establishing. It is possible to impregnate
the structure using a vacuum infusion method, then expand the structure prior to curing to the
desired depth. Other methods will be developed as the use of 3D structures becomes more
widespread. Another area needing research is the determination of structural properties.
Although the test methods will be determined by the requirements of the end use application,
some experimental analysis on 3D Honeycomb structures has already started [8]. The
dependency of commercial success on availability of machines has been highlighted previously
[9], however by using current weaving technology, success can more easily be achieved.
Examples of rapid growth within 3D woven structures are evident already within the UK and
USA. Autoliv, manufacturers of automotive components are responsible for investing in over
150 weaving looms and Jacquard shedding machines to weave 3D Inflatable Airbags at their UK
facility. The recent investments in Unival Technology and new manufacturing facility with
expansion capability at Sigmatex, demonstrates supplier commitment to this technology and
positive expectations for future growth in the 3D Carbon Composites Market.
9. REFERENCES
1. Khokar, Nandan. Second-Generation Woven Profiled 3D Fabrics from 3D-Weaving: The
First World Conference on 3D Fabrics and Their Applications. Manchester: UMIST,
2008.
2. Sulzer Textil. Weavers Digest. 2002. 27 Nov. 2008.
<http://www.sultex.com/wd_02_03_e.pdf>
3. Chen, Xiaogang. CAD/CAM of 3D woven fabric for conventional looms: The First
World Conference on 3D Fabrics and Their Applications. Manchester: UMIST, 2008.
4. Mohamed, Mansour, H et al. Method of forming variable cross-sectional shaped threedimensional fabrics. USP 5085252. 04 Feb. 1992.
5. Chiu, Chang-Hsaun. “Weaving Method of 3D woven performs for advanced composite
materials.” Textile Research Journal. 73(1) (2003): 37-41.
6. Busgen, Alexander. Simulation and realisation of 3D woven fabrics for automotive
applications: The First World Conference on 3D Fabrics and Their Applications.
Manchester: UMIST, 2008.
7. Chen, X., Sun, Y. & Gong, X. ”Design, Manufacture, and Experimental Analysis of 3D
Honeycomb Textile Composites Part 1: Design and Manufacture” Textile Research
Journal. 78(9) (2008):771-781
8. Chen, X., Sun, Y. & Gong, X. “Design, Manufacture, and Experimental Analysis of 3D
Honeycomb Textile Composites, Part II: Experimental Analysis” Textile Research
Journal. 78(11)(2008):1011-1021
9. Bogdanovich.A.E., Mungalov.D. & Duke.P.W. “New 3-D Rotary Braiding Technology
for High-Speed Manufacturing of Unitary, Complex Shape Preforms and Composites”:
The First World Conference on 3D Fabrics and Their Applications.Manchester: UMIST,
2008.