1. Lecture 24 – Fibre-reinforced composite materials
Prescribed Text:
Ref 1: Higgins RA & Bolton, Materials for Engineers and Technicians, 5th edition, Butterworth Heinemann. ISBN:
Readings:
Callister: Callister, W. Jr. and Rethwisch, D., 2410, Materials Science and Engineering: An Introduction, 8th Edition, Wiley, New York. ISBN
Ashby 1: Ashby, M. & Jones, D., 2411, Engineering Materials 1: An Introduction to Properties, Applications and Design, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN:
Ashby 2: Ashby, M. & Jones, D., 2411, Engineering Materials 2: An Introduction to Microstructures and Processing, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN:
Lecture (2 hrs):
Ref 1, Ch 1: Engineering materials;
Ref 1 Ch 2: Properties of materials.
Laboratory 1 (2 hrs): Hardness test
Callister: Ch 1, 2, 24-24
Ashby 1: Ch 1, 2
Ashby 2: Ch 1 1

2. Fibre-reinforced composite materials
Reference Text
Section
Higgins RA & Bolton, Materials for Engineers and Technicians, 5th ed, Butterworth Heinemann
Ch 24
Reference Text
Section
Engineering Materials and Processes

3. Fibre-reinforced composite materials (Higgins 24)
Wood can be thought of as a fibre composite: Fibres are the cells (tracheids) and glued together by the matrix (lignin).
Engineering Materials and Processes

4. Fibre-reinforced composite materials (Higgins 24)
Man-made fibre-reinforced composites
• Matrix materials, such as thermosetting or thermoplastics polymers
and some low-melting point metals, reinforced with fibres of carbon,
glass or organic polymer.
• Polymers, usually thermosetting, reinforced with fibres or laminates
of woven textile materials.
• Vehicle tyres in which vulcanised rubber is reinforced with woven
textiles and steel wire.
• Materials such as concrete reinforced with steel rods.
Engineering Materials and Processes

5. 24.2 Unidirectional Composites (Higgins 24.2)
Relative density of composite
Tensile strength of composite
Modulus of composite
Higgins
Engineering Materials and Processes

6. 24.3 Fibres (Higgins 24.3) 24.3.1 Glass fibre 24.3.2 Carbon fibre
Boron fibre
Aramid fibre (Kevlar)
Other fibres
Carbon
Aramid (Kevlar)
Glass
Engineering Materials and Processes

7. 24.3 Fibres (Higgins 24.3)
Higgins
Engineering Materials and Processes

8. 24.4 Matrix materials (Higgins 24.4)
• It should be stable to a temperature at which the properties of the
fibre begin to deteriorate.
• It must be capable of resisting any chemical attack by its
environment.
• It should not be affected by moisture.
Thermosetting resins
Thermoplastic polymers
Metals
Engineering Materials and Processes

9. 24.5 Mechanical properties (Higgins 24.5)
Engineering Materials and Processes

10. 24.6 Fibre-composite manufacture (Higgins 24.6)
• Rovings. A 'roving' of glass fibres, which may be several kilometres
in length, consists of 'strands', or bundles of filaments wound on to a
'creel'. A 'strand' contains some 200 filaments, each about 10 um in
diameter. Bundles of continuous carbon fibres are known as 'tows'.
• Woven fabrics in various weave types.
• Chopped fibres, usually between 1 mm and 50 mm long.
Continuously produced sections (rod, tube or channel), or sheet,
from which required lengths can be cut. Such a process can only
produce composites which are anisotropic in their properties,
strength being in a direction parallel to the fibre direction.
Composites manufactured as individual components. Here the fibre
may be woven into a 'preform' which roughly follows the mould or
die contour. In this case, the mechanical properties will tend to be
multi-directional.
Higgins
Engineering Materials and Processes

11. 24.6 Fibre-composite manufacture (Higgins 24.6)
Poltrusion
Higgins
Engineering Materials and Processes

12. 24.6 Fibre-composite manufacture (Higgins 24.6)
'Hand-and-spray' placement
Press moulding
Resin-transfer moulding
Metal matrix composites
Fibreglass/polyester Boat Hull
Engineering Materials and Processes

13. 24.7 Uses of fibre-reinforced composites (Higgins 24.7)
The most important of these materials commercially are polymer matrix
composites reinforced with either glass, carbon or aramid fibres.
The following characteristics of fibre composites commend their use:
• Low relative density and hence high specific strength and modulus
of elasticity.
• Good resistance to corrosion.
• Good fatigue resistance, particularly parallel to the fibre direction.
Higgins
Engineering Materials and Processes

14. 24.7 Uses of fibre-reinforced composites (Higgins 24.7)
This wind turbine blade is fibreglass – the fibres can be clearly seen. The tower itself is usually steel.
Oldenburg in northern Germany 2006
Engineering Materials and Processes

15. 24.8 Reinforced wood (Higgins 24.8)
The development of strong synthetic resin adhesives some years ago
resulted in much progress in the use of timber as a constructional
material. Also called ‘engineered wood’.
Laminated wood
Plywood, blockboard and
particleboard
Higgins
Engineering Materials and Processes

16. 24.8 Reinforced wood (Higgins 24.8)
Corrugated cardboard
Laminated boards
Complex anatomy of a carton.
Image: Carton Council
Engineering Materials and Processes

17. 24.9 Reinforced concrete (Higgins 24.9)
Steel reinforcing is designed to take tension, while concrete assumed to have zero tensile strength but takes compression.
Higgins
Engineering Materials and Processes

18. Engineering Materials and Processes

19. 24.9 Reinforced concrete (Higgins 24.9)
Compression tests on concrete
Ductile materials simply squash (barrel). Brittle materials often fracture at 45o (due to shear stress being much lower than compressive stress).
Compression is the standard test for concrete.
Compression test for Concrete
Wikipedia
Engineering Materials and Processes 19

20. Concrete Test High Strength Concrete
Concrete is not usually this strong, so it doesn’t usually explode like this…
The numbers: (Imperial/US units)
15.9 ksi or 200,000 lbs on a 4" diam cylinder.
Convert this to metric = 110Mpa
Concrete is usually about 20MPa, structural about 40MPa, and higher strength usually prefabricated since the W/C ratio must be very low (dry).
Compression test for Concrete
You Tube
rutgerscivilengr
Online
Offline
Engineering Materials and Processes 20

21. Resources. Ashby diagrams Young's modulus - Density
Young's Modulus - Cost
Strength - Density
Strength - Toughness
Strength - Elongation
Strength - Cost
Strength - Max service temperature
Specific stiffness - Specific strength
Electrical resistivity - Cost
Recycle Fraction - Cost
Energy content - Cost
h ttp://
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22. Videos Composite Materials
Cook, Jerome T. [US]: Society of Manufacturing Engineers, c2005. DVD (17 min.).
Part A: Hand lay-up, theory, open mould chopped roving, marine, vacuum bagging
Part B: Resin infusion, resin transfer, compression moulding, pultrusion, filament winding, continuous profile, bulk casting, centrifugal casting
Features an explanation of the mechanical properties of thermoset fiber-reinforced composites. The primary types of reinforcement materials are examined as well as the major matrix materials. The use of thermoplastic composite materials is also highlighted.
Mt Druitt College Library:
DVD /COMP
Recommended Viewing: All sections.
h ttp://
S how this website on screen. Will be using this later.
Engineering Materials and Processes 22

23. Resources. Wikipedia: Fibre-reinforced plastic
Wikipedia: Composite material
Ashby diagrams
h ttp://
S how this website on screen. Will be using this later.
Engineering Materials and Processes 23

24. Glossary Anisotropic Chopped fibre Rovings Unidirectional Woven mat
Chopped strand mat
Filament wound
Matrix
Poltrusion
Aramid
Carbon fibre
Engineering Materials and Processes

25. Define all glossary terms
QUESTIONS
Higgins Ch24, Newell, Timmings, Sheedy, Callister, Ashby
Define all glossary terms
Explain the issues of making strong concrete regarding water ratio, cement ratio, aggregate and sand, curing time and temperature, curing humidity. Explain what would be done to achieve high strength and low shrinkage.
What is a cermet and what are they used for? Give some examples of cermets and explain what properties they have that make them suitable for their purpose.
Give five reasons for a particle to be added to a matrix – include a range of different types of particle composites.
Explain how small particles can strengthen a ductile metal matrix even when the particles are rounded. (Dispersion hardened material).
Obsidian is a naturally occurring (usually dark) volcanic rock. Granite has large visible crystals and forms deep underground. Which one is more likely to be a glassy structure? Explain.
Explain why fibres are available in woven mat, chopped strand mat and filament. Give examples of each.
Polyester is common with glass and epoxy with carbon. Give reasons. Give advantages and disadvantages of each matrix resin.
Engineering Materials and Processes 25

26. QUESTIONS: Fibre Composites
Higgins Ch24, Newell, Timmings, Sheedy, Callister, Ashby
Compare and contrast the advantages and limitations of the following systems of reinforcing concrete: (a) simple reinforcement, (b) prestressed reinforcement, (c) post-tensioned reinforcement.
Explain what is meant by the particle hardening of a composite material and the dispersion hardening of a composite material. In each case give an example of such a material, together with a typical application.
Compare the four main types of water storage tank for domestic purposes: Polyethylene, fibreglass, galvanised steel and concrete. See
Engineering Materials and Processes 26