2. Composite Material
• Two inherently different materials that when
combined together produce a material with
properties that exceed the constituent
materials.
4. Fiber Reinforced Polymer Matrix
Matrix
• Transfer Load to Reinforcement
• Temperature Resistance
• Chemical Resistance
Reinforcement
• Tensile Properties
• Stiffness
• Impact Resistance
5. Textile Preform
• In the recent years, the use of textile structures made from high
performance fibres is finding increasing importance in composites
applications. In textile process, there is direct control over fibre
placements and ease of handling of fibres.
• Besides economical advantages, textile preform technologies also
provide homogenous distribution of matrix and reinforcing fibre. Thus,
textile preforms are considered to be the structural backbone of
composite structures.
• This technology is of particular importance in the context of improving
certain properties of composites like inter-laminar shear and damage
tolerance apart from reducing the cost of manufacturing.
6. Materials Used for Preforms
• High performance multifilament fibres, such
as glass, aramid and carbon, which provide
high tensile strength, modulus, and
resistance to chemicals and heat to various
types of preforms.
7. Techniques Used For Preforms
Weaving
Direction of yarn introduction : Two (0°/90°) (warp and weft)
Fabric formation principle : Interlacing (By selective insertion
of 90° yarns into 0° yarn system)
Knitting
Direction of yarn introduction : One (0° or 90°) (warp or weft)
Fabric formation principle : Interlooping (By drawing loops of yarns
over previous loops)
8. Techniques Used For Preforms
• Braiding
• Direction of yarn introduction : One (machine direction)
• Fabric formation principle : Intertwining (Position displacement)
• Nonwoven
• Direction of yarn introduction : Three or more (orthogonal)
• Fabric formation principle : Mutual fibre placement
• Stitched fabrics (non-crimp fabrics)
9. Fabric description
• warp fibres
picks (shots) run full length of the fabric
• weft fibres (shuttle direction in weaves)
ends run across the fabric
• fabrics are designated by areal weight
normally grams/square metre (gsm)
Weft in weave
Course in knitWarp in weave
Wale in knit
10. Balanced fabric
a balanced fabric would have
• equal numbers of
equal weight tows/metre
in both warp and weft
Crimp
crimp ratio = yarn length/cloth length
11. Woven fabrics 1: weave
styles
• Plain
o high crimp, poor mechanical properties
• Twill
o intermediate properties
• Satin
o low crimp, good mechanical properties
o but beware of orientation of each face
• also matt, leno, flow-enhancement …
12. Woven fabrics 2
• plain weave
• 2 orthogonal sets of fibres (ηo = 1/2)
• high crimp, hence
out of plane orientation (∴ηo < 1/2)
18. Three-dimensional fabrics
• 3-D weaving
o usually multi-layer
3D angle interlock (shown)
3D orthogonal (90° binder)
o used for preforms
Layer to layer interlock weave Angle interlock weave Orthogonal non-crimp interlock weave
19. Braid
• interlacing three or more threads to produce
a tubular reinforcement
with fibres at ±45° to the principal axis of the tube
20. Knitted fabrics
• knitting is intermeshing of loops of yarn
• Marvin (1961-69) knitted rocket nose cones
• can form complex shapes
or create a matrix for aligned fibres:
• WIWK = weft-insertion warp knit
or = warp-insertion weft knit
•
21. Stitched (non-crimp) fabrics
detail of the stitch photo of real fabric cross-section of laminate
•unidirectional layers stitched together
• Beware! stitch fibre
may be incompatible with the matrix
•
22. Bonded/felted fabrics
• Chopped strand mat
• Unifilo continuous random swirl fibre mat
• Bonding reinforcing scrims (e.g. Crenette)
23. Properties of some textile performs
Textile
Preform
Advantage Limitation
Low crimp,
uniweave
High in-plane properties; good
taliorability; highly automated
preform fabrication process
Low transverse and out-of-plane
properties; poor fabric stability;
labor intensive ply lay-up
2-D Woven Good in-plane properties; good
drapability; highly automated
perform fabrication process;
integrally woven shapes possible;
suited for large area coverage
and extensive data base
Limited taliorability for off-axis
properties ; low out-of-plane
properties
24. Properties of some textile performs
Textile
Preform
Advantage Limitation
3-D Woven Moderate in-plane and out-of-
plane properties; automated
preform fabrication process and
limited woven shapes are
possible
Limited taliorability for off-axis
properties and poor drapability
2-D Braid Good balance in off-axis
properties; automated preform
fabrication process; well suited
for complex curved shapes; good
drapability
Size limitation due to machine
availability and low out-of-plane
properties
25. Properties of some textile performs
Textile Preform Advantage Limitation
3-D Braid Good balance in in-plane
and out-of-plane properties;
well suited for complex
shapes
Slow preform fabrication
process; size limitation due
to machine availability
Multi-axial warp knit Good taliorability for
balanced in-plane
properties; highly automated
preform fabrication process;
multi-layer high throughput;
material suited for large
area coverage
Low out-of-plane properties
Stitched fabrics Good in-plane properties;
highly automated process;
provides excellent damage
tolerance and out-of-plane
strength and excellent
assembly aid
Small reduction in in-plane
properties; poor accessibility
to complex curved shapes
26. Conclusions
• Optimization of traditional textile technologies and development of new textile
production techniques will help to reduce manufacturing cost of advanced
composites.
• With the advancement in geometrical modeling and predictive calculations of the
physical and structural properties of textile preforms, desired textile preforms can
be tailored with essential modifications in preform specifications as well as in
structure and properties of fibres and yarns.
• Although simple 2D textile preforms are finding extensive usage in the
commercial applications, the advanced 3D textile preforms are being used mostly
in defense and aerospace applications only.
• As composites with 3D textile preforms can effectively replace conventional
materials, it is necessary to develop cost effective ways of producing complicated
3D textile preforms and evaluating the properties relevant to commercial
applications.
