1. Composite Materials Fundamental considerations
How do composite materials differ from other engineering materials?
What are the constituent materials, and how do their properties compare?
How do the properties of the composite depend on the type, amount and arrangement of the constituents?
How are composite products made, and why does manufacture affect quality?

2. Fibres have better stiffness and strength compared to bulk materials
Atomic or molecular alignment (carbon, aramid)
Removal of flaws and cracks (glass)
Strain hardening (metals)

3. As fibre diameter is reduced, so is maximum possible crack size in glass. Theoretical strength is achieved in defect-free material (zero diameter!).
D Hull: Introduction to Composite Materials
J Gordon: The New Science of Strong Materials
Carbon fibre – alignment of graphite sheets. Strong, in-plane covalent bonds; weak secondary bonds between sheets (cf polymer structures).

4. Carbon fibres seen under the electron microscope
Carbon fibres seen under the electron microscope. Note the irregular surface. Fibre diameters are around 5 – 7 microns (thousandths of a mm).

5. Glass fibres being drawn from the furnace
Glass fibres being drawn from the furnace. Molten glass emerges through a bushing – the rate of pulling determines the fibre diameter. Because the fibres are so small, they lose heat very quickly.

6. The surface of a fractured composite, containing both carbon and glass fibres. Note the larger, smoother glass, and regions where fibres have been pulled out of the plastic matrix.

7. steel
aluminium
heat-treated aluminium alloy
heat-treated alloy steel

8. Compare stiffness and strength per unit weight:
Tensile strength / density
Tensile modulus / density

9. Nominal properties – ‘high strength’ carbon fibres
tensile strength (GPa)
tensile modulus (GPa)

10. Nominal properties – ‘intermediate-high modulus’ carbon fibres

12. Young's Modulus (SWNT) ~ 1 TPa (1000 GPa)
~ 0.02 mm
Young's Modulus (SWNT) ~ 1 TPa (1000 GPa)
Young's Modulus (MWNT) 1.28 TPa
Maximum Tensile Strength ~ 30 GPa (30,000 MPa)

13. Most reinforcing fibres (and thermosetting resins) are brittle (elastic to failure)
Hollaway (ed), Handbook of Polymer Composites for Engineers

14. Types of Natural Fibre
Bast fibres (flax, hemp, jute, kenaf…) - wood core surrounded by stem containing cellulose filaments
Leaf fibres (sisal, banana, palm)
Seed fibres (cotton, coconut (coir), kapok)
modulus / density

15. Structures cannot be made from fibres alone - the high properties of fibres are not realisable in practice
A matrix is required to:
hold reinforcement in correct orientation
protect fibres from damage
transfer loads into and between fibres

16. COMPOSITES - A FORMAL DEFINITION (Hull, 1981)
1. Consist of two or more physically distinct and mechanically separable parts.
reinforcement (discontinuous phase)
matrix (continuous phase) +
fibres or particles
short, ‘long’ or continuous

17. Examples of particulate composites
Concrete - hard particles (gravel) + cement (ceramic/ceramic composite). Properties determined by particle size distribution, quantity and matrix formulation
Additives and fillers in polymers: carbon black (conductivity, wear/heat resistance) aluminium trihydride (fire retardancy) glass or polymer microspheres (density reduction) chalk (cost reduction)
Cutting tool materials and abrasives (alumina, SiC, BN bonded by glass or polymer matrix; diamond/metal matrix)
Electrical contacts (silver/tungsten for conductivity and wear resistance)
Cast aluminium with SiC particles

18. Alternative matrix materials
Ceramic (CMCs)
Metal (MMCs)
Polymer (PMCs)
Fibre: SiC; alumina; SiN
Matrix: SiC; alumina; glass-ceramic; SiN
Fibres improve toughness
Fibre: boron; Borsic; carbon (graphite); SiC; alumina (Al2O3)
Matrix: aluminium; magnesium; titanium; copper
Fibres improve high temp creep; thermal expansion.
thermoplastic
thermoset
Tough; high melt viscosity; ‘recyclable’
Brittle; low viscosity before cure; not recyclable
The matrix material largely determines the processing method…

19. Composite property might be only 10% of the fibre property:

21. COMPOSITES - A FORMAL DEFINITION (Hull, 1981)
1. Consist of two or more physically distinct and mechanically separable parts.
2. Constituents can be combined in a controlled way to achieve optimum properties.

22. COMPOSITES - A FORMAL DEFINITION (Hull, 1981)
1. Consist of two or more physically distinct and mechanically separable parts.
2. Constituents can be combined in a controlled way to achieve optimum properties.
3. Properties are superior, and possibly unique, compared those of the individual components

23. Addition of properties:
GLASS POLYESTER = GRP
(strength) (chemical resistance) (strength and chemical resistance)
Unique properties:
GLASS POLYESTER = GRP
(brittle) (brittle) (tough!)

24. ADVANCED COMPOSITES vs REINFORCED PLASTICS
Aerospace, defence, F1…
Highly stressed
Glass, carbon, aramid fibres
Honeycomb cores
Epoxy, bismaleimide…
Prepregs
Vacuum bag/oven/autoclave
Highly tested and qualified materials
Marine, building…
Lightly stressed
Glass (random and woven)
Foam cores
Polyester, vinylester…
Wet resins
Hand lay up, room temperature cure
Limited range of lower performance materials

25. Why are composites used in engineering?
Weight saving (high specific properties)
Corrosion resistance
Fatigue properties
Manufacturing advantages: - reduced parts count - novel geometries - low cost tooling
Design freedoms - continuous property spectrum - anisotropic properties

26. Anisotropic properties - fibres can be aligned in load directions to make the most efficient use of the material

27. Why aren’t composites used more in engineering?
High cost of raw materials
Lack of design standards
Few ‘mass production’ processes available
Properties of laminated composites: - low through-thickness strength - low interlaminar shear strength
No ‘off the shelf’ properties - performance depends on quality of manufacture

28. Material quality depends on quality of manufacture.
There are no ‘off the shelf’ properties with composites. Both the structure and the material are made at the same time.
Material quality depends on quality of manufacture.

29. Metal (steel, aluminium, titanium, magnesium…) Composite (carbon fibre / epoxy)?

30. Aluminium or composite?
2005: Airbus engineers are claiming Boeing has rushed the development of the 7E7 Dreamliner. In particular, they say composite technology is not mature enough to build an all-composite fuselage. But the claims may be no more than a marketing ploy, in response to Boeing's criticism of weight overruns on the Airbus A380.

31. SEATTLE, Jan. 11, 2005 –
Boeing recently completed the first full-scale composite one-piece fuselage section for its new 7E7 Dreamliner program, demonstrating concepts for 7E7 production that begins next year. The structure, 7 m long and nearly 6 m wide, is the 7E7's first major development piece.
"This is a piece of aviation history," said Walt Gillette, Boeing vice president of Engineering, Manufacturing and Partner Alignment. "Nothing like this is already in production. Hundreds of aerospace experts from Boeing and our partners developed everything, including the design, tools that served as the mold, programming for the composite lay-down, and tools that moved the structure into the autoclave."
He added that using composites "allowed us to create optimized structural designs and develop an efficient production process. We now see how all advanced airplanes will be built from this time forward."

32. Boeing's Revolutionary Lightweight Jetliner Faces Serious Problems
For Boeing, the 787 Dreamliner, with its radical new lightweight design, represents far more than a potentially juicy profit stream. The carbon-fiber-reinforced plastic aircraft is supposed to be the symbol of a new Boeing — a visionary company that has transcended its recent ethical scandals, designed the most innovative commercial plane ever, and devised the most sophisticated manufacturing process in history to produce the aircraft.
But as crucial deadlines loom, Boeing’s engineers are wrestling with several significant technical and production problems that could threaten the scheduled 2008 delivery of the jetliner.
At a time when Boeing has left itself with little margin for error, the wide-ranging series of glitches could create a domino effect if not resolved quickly. The most important piece of bad news — the fuselage section, the big multi-part cylindrical barrel that encompasses the passenger seating area, has failed in company testing. That’s forcing Boeing to make more sections than planned, and to reexamine quality and safety concerns.
Elsewhere in the aircraft, suppliers are struggling to meet Boeing’s exacting technological standards and ambitious production deadlines. The first two nose sections, for instance, were deemed unacceptable by Boeing. Software programs designed by a variety of manufacturers are having trouble talking to one another. And the overall weight of the airplane is still too high — especially the single biggest part of the 787, the carbon-fiber wing.
The first big sign of struggle with the 787 surfaced three weeks ago at Boeing’s Developmental Center in south Seattle. That’s when engineers discovered that worrisome bubbles were developing in the skin of the fuselage during the process of baking the plastic composite tape in big oven-like machines.
But the main challenge is the sheer size of the fuselage sections. These require multiple layers of carbon-fiber tape to assure structural integrity. However, each added layer increases the likelihood of variations or flaws, say composite experts, such as bubbles on the skin. Bubbles could weaken the material and eventually cause cracks by allowing water to seep under the surface, then freeze up and expand at high altitudes, raising the possibility that the fuselage could crack under extreme conditions. Bair says Boeing has located the source of the problem.
Seattle, Washington, USA, June 8, 2006

33. Composite – wood, glass, carbon?
Manufacture - prepreg, infusion…?

35. ADVANTAGES OF COMPOSITES (for construction applications)
Aesthetic appeal
Ability to mould complex shapes
Various surface finishes available
Lightweight
Durability / Corrosion resistance
Parts integration
Cost effectiveness
Electrical properties

36. POSSIBLE APPLICATIONS (in construction)
Roofs / canopies
Complete buildings
Cladding panels
Masts & towers
Domes
Unusual architectural features / structures
Radomes
Permanent or temporary formwork
Strengthening / repair of conventional structures
Tanks, covers, pipes, ducts etc

37. BRIDGE APPLICATIONS OF COMPOSITE MATERIALS

38. GRP LOUVRES AT LANCASTER UNIVERSITY

39. HARARE INTERNATIONAL AIRPORT ARCHITECTURAL GRP STRUCTURE ON THE TOP OF THE AIR TRAFFIC CONTROL TOWER

40. PHOTOS COURTESY OF NORTHSHORE COMPOSITES
FRP MOSQUE DOMES
PHOTOS COURTESY OF NORTHSHORE COMPOSITES

41. MILLENNIUM DOME HOME PLANET ZONE

42. FRP SPHERICAL RADOMES

43. FRP CYLINDRICAL RADOMES

44. FRP OBSERVATION CABIN & CARBON FIBRE MAST
GLASGOW SCIENCE CENTRE
FRP OBSERVATION CABIN & CARBON FIBRE MAST
Photo - Carrillion

45. GLASGOW SCIENCE CENTRE OBSERVATION CABIN

46. CABIN MANUFACTURE

47. CABIN INSTALLATION

48. CONCRETE COLUMN REINFORCEMENT

49. FRP LIGHTSTATIONS

50. FRP BRIDGE ENCLOSURES

51. FRP PULTRUDED STRUCTURAL FRAME

52. PORTSMOUTH SPINNAKER TOWER
SPIRE SECTION MAY BE MANUFACTURED IN COMPOSITES

53. Composite Materials for the construction industry Summary
Huge potential for polymer composites in civil engineering/construction applications.
Large structures need particular types of manufacturing process.
Raw materials are expensive – need low-cost manufacture and justification for composites.
Building industry is conservative – resistance to ‘new’ materials.
Design codes for composite structures – available but not widely adopted.
David Kendall, CETEC (2001)