3. Composite materials –
Introduction
• Definition: a material composed of 2 or more
constituents
– Reinforcement phase (e.g., Fibers)
– Binder phase (e.g., compliant matrix)
• Advantages
– High strength and stiffness
– Low weight ratio
– Material can be designed in addition to the structure
– Can manufacture structures and eliminate joints
4. Methods of Reinforcing Plastics
Figure 9.2 Schematic illustration of methods of reinforcing plastics (matrix) with (a) particles, (b)
short or long fibers or flakes, and (c) continuous fibers. The laminate structures shown in (d) can
be produced from layers of continuous fibers or sandwich structures using a foam or honeycomb
core (see also Fig. 16.50).
5. Introduction
FRP Composite materials - are known as
Fiber Reinforced Composite materials which
consists of fibers of high strength and modulus
embedded in or bonded to a matrix with distinct
interfaces between them
6. Constituents of Composite Materials
• Major constituents are:
a) Fiber
b) Matrix
c) Fillers
d) Coupling agents
e) Coatings
7. FIBER
• Principal load carrying member.
• Main constituent and occupy largest volume
fraction.
• The diameter of a fiber will be around 10μm.
• Commercially available fibers are of various
types such as glass, carbon and kevlar 49.
• Fibers may be of Continuous or Discontinuos
(chopped lengths) in lengths
8. • Fibers are reinforced inside the matrix
• Keeps fiber in desired location and orientation.
• Acts as a load transfer medium
• Protects fiber from environmental damages due
to elevated temperatures and humidity.
• Matrix material may be
a) Metal matrix
b) Polymeric matrix
c) Ceramic matrix
MATRIX
9. COUPLING AGENTS AND COATINGS
• These are applied on the fiber to improve their
wetting with matrix
• To promote bonding between the fiber-matrix
interface
• Protect the fiber from moisture and reactive fluids
• Coupling agent used with glass fiber is silanes
(Organo functional silicon compound)
10. FILLERS
• To reduce cost
• Dimensional Stability
• Increase modulus
• Reduce mold shrinkage
• Control the viscosity
• Produce smoother surface
• Common filler material – Ca Co3
12. TERMINOLOGY
• Lamina or Ply – incorporation of fiber into a thin
layer of matrix [ 0.1 – 1 mm thick]
• Laminate – obtained by stacking a number of
thin layer of fibers and matrix (Ply) for desired
thickness
• Strand – Commercial form of fiber, produced by
gathering number of filaments (10μm) – 204 or
more
• Roving – a group of untwisted parallel strands
wound in cylindrical forming
13. • A lamina (laminae) is any
arrangement of unidirectional
or woven fibers in a matrix.
Usually this arrangement is
flat, although it may be
curved, as in a shell.
• A laminate is a stack of
lamina arranged with their
main reinforcement in at least
two different directions.
19. CHARACTERISTICS OF COMPOSITES
i) Substitution for Metals due to
Low Specific Gravity
High Strength to Weight ratio
High Modulus to Weight ratio
An – iosotropic in nature
ii) Properties depend strongly on direction of
measurement (directional dependent)
For example tensile strength is maximum in
longitudinal direction
20. CHARACTERISTICS OF COMPOSITES
iii) Greater design flexibility
Opportunity to tailor its property
according to the need for example
selectively reinforcing to attain maximum
stress, Increased stiffness
iv) Heterogeneous nature provides
mechanism for high energy absorption
comparable to yielding. Therefore
composite exhibit gradual deterioration
21. CHARACTERISTICS OF COMPOSITES
v) Coefficient of thermal expansion are lower
than metals therefore exhibits higher
dimensional stability over a wide range of
temperature
vi) High internal damping – resulting in
reduced noise and vibration
vii) Non – corroding behavior
22. APPLICATION
• IN THE FIELD OF MILITARY AND
COMMERCIAL AIR CRAFT [ Weight reduction
and Dynamic frequency tailoring]
Carbon fibers and Kevlar 49 used in
wing, fuselage and empennage components
Fiber reinforced epoxies are used in
rotor blades for military and commercial
helicopters [ Manufacturing flexibility]
Kevlar 49 or S-glass fibre reinforced
epoxies used in filament wound motor cases
23. APPLICATION
• SPACE APPLICATIONS
Boron fiber reinforced Aluminium tubes for
mid fuselage trusss structure
Aluminum honey comb in combination with
Carbon fiber reinforced epoxy face sheets for
pay load bay door
Carbon fiber reinforced epoxy tube for
manipulator arm, Artificial satellites
Kevlar 49 Fiber reinforced epoxy pressure
vessels
24. APPLICATION
• AUTOMOTIVE APPLICATION
E- Glass Fiber Used To Replace Leaf Spring
• SPORTING GOODS [ Better damping and to
store elastic energy]
Tennis racket – Carbon or Boron fiber
reinforced epoxies as Skin material and
Urethane foam as core material leads to weight
reduction as well as greater stiffness.
• MARINE APPLICATION
Boat hull, deck, bulk head ,frames etc
25. • Strength of composite material depends
upon
• Orientation of the fiber
• Type of fiber
• Amount of fiber present.
• Fiber orientation in each layer as well as
stacking sequence of the plies plays a
major role in the strength and modulus of
the composite laminates.
26. Comparison of Composites
with Al
• Density of aluminum alloy approximately 2800 kg/m3
• Density of carbon/epoxy approximately 1580 kg/m3
• Tensile strength of aluminum alloy 7075-T6 is 570
MPa
• Tensile strength of carbon/epoxy 1830 MPa
• Strength Weight Ratio of Al Alloy is 0.204
• Strength Weight Ratio of carbon/epoxy is 1.158
27. • Vehicles
• Highway structures
E- Glass Fiber Used to Replace Leaf
Spring
Body parts, drive shaft, springs
TRANSPORTATION
34. COMPOSITE MATERIALS IN MEDICAL APPLICATIONS
EXAMPLE OF HARD TISSUE
Total Hip replacement
- It is the most common artificial joint in humans.
35. COMPOSITE MATERIALS IN MEDICAL APPLICATIONS
EXAMPLE OF HARD TISSUE
Total Hip replacement
36. COMPOSITE MATERIALS IN MEDICAL APPLICATIONS
EXAMPLE OF HARD TISSUE
Total Hip replacement
- Metal is the most popular material for Hip
replacement but has “stress shielding problem”.
- Proposed composites:
Polyether-imide reinforced with glass and
carbon fibers.
Polysulfone reinforced with carbon fibers
