1. INTRODUCTION TO ADVANCED COMPOSITE MATERIALS
Dr. ZAFFAR M. KHAN

2. Industrial Application
Fabrication
Introduction
Processing/NDT
INDUSTRIAL
COMPOSITES
Industrial Application
Design Analysis

3. Scope Historical background, nature and advantages of composites
Types of matrices
Fibers and their characterization
Physical and mechanical properties of composites
Application in aircraft, sports goods, medical, civil engineering and automobile industries

4. First Composite Solo Flight

5. Relative importance of Engineering Materials with respect to time period

6. Trends of Carbon Fiber Composite Growth

7. Carbon Composites for Defence Systems

8. Composite Materials
Composite materials are macroscopic combination of two or more materials each having distinct properties. It is composed of:
Matrix (Black)
Reinforcement (White)
Iinterphase

9. Advantages of Composite Materials
Significant weight saving which increases payload and/or range along with fuel saving.
Maximum specific strength and stiffness make them lighter than aluminum, stronger than steel.
Permits aero-elastic tailoring of structural components.
Flexibility of Design
Integrated structures diminishes application of rivets.
Enhanced fatigue life.
Absence of corrosion.
Reduced operational, manufacturing
and maintenance cost.

10. Comparison of Composites with Metals

11. Aero-elastic Composite Structure
The composite structure is tailored to meet varying aerodynamic requirements in aircrafts, cars wind and rotor blades. It reduces drag and enhances energy conservation.

12. Flexibility of Composite Design

13. Influence of Vibrations on Composites
The vibration damping characteristics
of composites are far superior as
Compared to metals for following
reasons;
Matrix visco-elastic effects and
micro-cracking
Blunting of crack by in fibers
transverse direction
Debonding and sliding of fibers
in axial direction.

14. Integrated Structure
Integrated composite structure reduces rivets and associated weight which leads to integrated structure of aircraft, automobiles and other engineering systems.

15. Matrix Constituent Types: Roles: Ceramic (Temp < 6000°F)
Metallic (Temp < 4000°F)
Polymeric (Temp < 600°F)
Determine:
Environmental resistance
Shelf Life
Compressive & transverse mechanical properties of composite
Roles:
Binds and holds reinforcemaent together
Determines composite shape and geometry
Transfers stresses to reinforcement

16. Ceramic Matrix Oxides, carbides, nitrides, borides and silicates characterizes high degree of thermal and dimensional stability.
Manufacturing Process:
Cast from slurries or processed into shape with organic binder and then fired/ sintered/ cured at very high temperature.
Examples:
Silicon carbide filament in Silicate matrix
Boron carbide in Alumina matrix
Aluminum oxide in Alumina matrix
Metal particles in ceramic matrix  CERMETS
Applications:
Rocket nose cone and Nozzle
Combustion Chamber
Skin of space plane/ spacecraft
Problem Areas:
Interface problem

17. Metal Matrix
Relatively lower densities of aluminum, titanium and magnesium are reinforced by high strength/ stiffness fibers. Organic fibers are not used due to high processing temperatures. Most common fibers are;
Metal fibers of beryllium, molybdenum, steel and tungsten
Boron, silicon carbide, silicon boride coated fine wires
Whiskers of aluminum oxide, boron carbide or silicon carbide
Manufacturing Process:
Metal matrix may be coated onto fibers by electro deposition, vapor deposition or plasma spray followed by hot pressing
Fibers can be infiltrated with liquid metal under high process
Fiber pressed between metal foils and sintered with powder metals
Examples:
Aluminum, titanium alloys, silver, magnesium, cobalt and copper matrices
Applications:
Space shuttle, piston ring, connecting rods, suspension components

18. Composed of long chains of hydro carbons
Polymeric Matrix
Composed of long chains of hydro carbons
Thermoplastics:
Softens when heated and hardens when cooled.
Can be recycled.
Relatively tough
Low dimensional stability.
Styrenes, Vinyls, Acrylics,
Thermosets:
Hardens when heated.
Composed of long molecular cross links.
Cannot be recycled.
Relatively brittle.
Relatively greater dimensional tolerance.
Epoxies, urathanes, phenolics.

19. Comparison of Thermoset Versus Thermoplastic
PROPERTY THERMOSET THERMOPLASTIC
(FIBERITE 931 EPOXY) (ICI APC-2 PEEK)
Melt Viscosity Low High
Fiber Impregnation Easy Difficult
Prepreg Tack Good None
Prepreg Drape Good Poor
Prepreg Stability at 0° F 6 mos. -1 yr. Indefinite
Processing Cycle Hrs 15 sec 6 hr
Processing Temperature 350° F 700° F
Mechanical Properties Good Good
Environmental Durability Good Exceptional
Damage Tolerance Average Good
Database Large Average

20. Structural Performance Ranking of Materials

21. Temperature Response of Ceramic, Metallic & Polymeric Composites
Polymeric composites have maximum specific strength but has poor strength at elevated temperatures. Metal and ceramic composites retain their lower mechanical properties at elevated temperature. Selection of composites is determined by environmental temperatures.

22. Properties of Polymeric Matrices
EPOXY (THERMOSET)
Most widely used matrix in hi-tech applications
Outstanding adhesion
Low shrinkage during cure
Easy to process forgiving
Strong, tough
Extensive, reliable data base
POLYESTER (THERMOSET)
Most widely used matrix for less demanding applications
High shrinkage during cure
Poorer adhesion than epoxy
Very easy to process ; lower pressures and temperatures and shorter cure cycles than epoxy.
Lower cost than epoxy
In general, poorer properties than epoxy (and less expensive)
POLYIMIDE (THERMOSET)
Primarily for service at high temperature i.e. 600 F
Higher cost than epoxy
More difficult to process than epoxy ; more complex cure cycles, requires higher temperatures are pressures
Dark colours only
High brittleness
Propreg does not drape well ( tends to be a little shiff)
BISMALEIMIDE (THERMOSET)
Proposed to fill the gap between polyimide and high temperature epoxies i.e. 450 – 500 degrees F
Better strength than epoxy at high temperature
It has relatively simple are cycles more like epoxy than polyimide (Thus it is relatively easy to process
Application in X-wing vertical take off/landing sibors by Aircraft /copter.

23. URETHANE (THERMOPLASTIC)
PHENOLIC (THERMOSET)
Expensive and difficult to process; requires high cure pressure
Good electrical resistance
Self extinguishing and not toxic, thus it has received interest for aircraft interiors (for example :
graphite fabric reinforced phenolic facings for honeycomb floor panels )
URETHANE (THERMOPLASTIC)
Good toughness and abrasion resistance
Easily foamed and low heat transfer (thus, a common use is insulation )
Limited in service temperature
Commonly used in Reuction Injection Molding (RIM) to produce strong, stiff, light weight
“Self-skinned” structures
Reinforced with carbon fiber Ejection seats
PEEK (THERMOPLASTIC)
Tough, high impact resistance, high fracture toughness
Excellent abrasion resistance
Excellent solvent resistance
Low moisture absorption
Very high cost
New, not much data available
Requires very high processing temperature (600 degrees F) which complicates manufacturing
Prepregs are stiff (no drape); thus, flat laminates must first be made, then laminates
must be formed to shape with high temp and pressure. Manufacturing with prepregs
is still in development stage.

24. Thermoset Composites

25. Thermoplastic Composites

26. Thermoplastic Composites

27. Evolution of Epoxy Resin
Poly functional epoxy resin contains more than two epoxide group
FIRST GENERATION EPOXIES:
Example: NARMCO 5208, CIBA GEIGY – 914
Better dimensional stabile but inherently brittle.
Composed of:
 Tetra Glycidyl Derivative (Wt Fraction : 38.2 %)
 Triglycidyl Ether (33.4%)
 Dicyandiamide (5.0%)
 Poly Ether Sul Phone (23.4)
SECOND GENERATION EPOXIES:
Example: NARMCO 5245, CIBA GEIGY-924
 Addition of CTBN to original formulation
 Better damage tolerance, reduced hot /wet performance.
 Lead to phase separation which imparts desired toughness.

28. Reinforcement Constituent
Particulate: Good compression strength but poor tensile properties, and particles in cement.
Flakes: Effective solvent resistant but difficult fabrication.
Whiskers: High degree of strength but poor crack stopping properties.
Fibers: Better structural properties, crack stopping properties, flexibility of design requirement by changing orientation of fibers 0°, +45°, 90°
Stacking sequence
Types of fibers i.e. glass, carbon, kevlar & carbon

29. Milled Carbon Fibers
Carbon Fiber Pellets
Chopped Carbon Fibers
Carbon Fiber Mat

30. Micrographs of Carbon, Kevlar and Glass Fibers

31. Properties of High Performance Synthetic Fibers
CARBON
(2-Dimension)
KEVLAR
(1 Dimension)
GLASS
(3 Dimension)
ADVANTAGES
Max specific strength
Max specific modulus
High temp resistance
Tough
Light weight
No galvanic corrosion
Low notch sensitivity
DISADVANTAGES
Expensive
Low impact resistance
Promotes oxidation
Difficult machining
Poor compression
Absorbs moisture
Poor coupling to resin
High density
Low stiffness
APPLICATIONS
Rocket motors
Aircrafts members
Leading edges, ropes
Ballistic protection
Water tank, bathroom accessories, shelters
COST INDEX
High (6-7)
Intermediate (3)
Low (1-2)

32. Microstructure of Carbon Fibers
The covalently bonded aromatic chains of carbon fiber in the axial direction are held together by weak Wander wall bonds in transverse direction. The alignment of chains in axial direction determines their outstanding strength.

34. Fabrication of Carbon Fiber
Carbonization:
°F
Oxidation:
1000°C 
Graphitization:
°C 
Etching of fiber surface

35. Processing Temperature
The higher degree of temperature and tension during graphitization process leads to greater alignment of carbon chains and superior mechanical properties of carbon fibers, T-300 (Boeing-727, 737, 747 and Airbus-310) and T-800 (Boeing-777, Airbus-380, Osprey V22 and JSF).

36. Variation of Mechanical Properties of Carbon Fiber With Respect to Temperature

37. Chemical Kinetics of during Curing of CFRP

38. Kevlar Fibers
Kevlar: Aromatic carbon chains are held together by amide group (-CH-NH-).
Concentrated solution in strong mineral acid is processed through spinnerets into neutralizing bath. The fibers are washed, dried and heated in nitrogen at high temperature under tension.

39. Properties of Kevlar Fibers

40. Glass Fibers

41. Weave Architecture

42. Through Thickness Stitching

43. Fiber Architecture

44. Prepreg
Prepreg: The resin is impregnated in fibers by passing fibers through resin bath, oven and driers. The resin is advanced from A to B stage. The ready to mold material is stored for application.

45. Unidirectional and Fabric Prepreg

46. Composite Materials Summary

47. THANK YOU