Lecture 24 – Fibre-reinforced composite materials

1. Lecture 24 – Fibre-reinforced composite materials

2. Fibre-reinforced composite materials Engineering Materials and Processes

3. Fibre-reinforced composite materials (Higgins24) Wood can be thought of as a fibre composite: Fibres are the cells (tracheids) and glued together by the matrix (lignin). http://woodmagic.vt.edu Engineering Materials and Processes

4. Fibre-reinforced composite materials (Higgins24) 24.1.1 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 (Higgins24.2) 24.2.1 Relative density of composite 24.2.2 Tensile strength of composite 24.2.3 Modulus of composite Higgins Engineering Materials and Processes

6. 24.3 Fibres (Higgins24.3) 24.3.1 Glass fibre 24.3.2 Carbon fibre 24.3.3 Boron fibre 24.3.4 Aramid fibre (Kevlar) 24.3.5 Other fibres Carbon Aramid (Kevlar) Glass Engineering Materials and Processes

7. 24.3 Fibres (Higgins24.3) Higgins Engineering Materials and Processes

8. 24.4 Matrix materials (Higgins24.4) • 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. 24.4.1 Thermosetting resins 24.4.2 Thermoplastic polymers 24.4.3 Metals http://www.glowpaint.com.au Engineering Materials and Processes

9. 24.5 Mechanical properties (Higgins24.5) Higgins Engineering Materials and Processes

10. 24.6 Fibre-composite manufacture (Higgins24.6) • 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 (Higgins24.6) 24.6.1 Poltrusion Higgins Engineering Materials and Processes

12. 24.6 Fibre-composite manufacture (Higgins24.6) 24.6.2 'Hand-and-spray' placement 24.6.3 Press moulding 24.6.4 Resin-transfer moulding 24.6.5 Metal matrix composites Fibreglass/polyester Boat Hull http://rampageous.com Engineering Materials and Processes

13. 24.7 Uses of fibre-reinforced composites (Higgins24.7) 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 (Higgins24.7) This wind turbine blade is fibreglass – the fibres can be clearly seen. The tower itself is usually steel. Oldenburg in northern Germany 2006 http://www.solaripedia.com/13/25/dangers_of_wind_power.html Engineering Materials and Processes

15. 24.8 Reinforced wood (Higgins24.8) 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’. 24.8.1 Laminated wood 24.8.2 Plywood, blockboard and particleboard Higgins Engineering Materials and Processes

16. 24.8 Reinforced wood (Higgins24.8) 24.8.3 Corrugated cardboard Laminated boards http://www.photos-public-domain.com Complex anatomy of a carton. Image: Carton Council Engineering Materials and Processes

17. 24.9 Reinforced concrete (Higgins24.9) 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 (Higgins24.9) 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

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

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 Engineering Materials and Processes

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 thermosetfiber-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 620.192/COMP Recommended Viewing: All sections. Engineering Materials and Processes

23. Resources. Wikipedia: Fibre-reinforced plastic Wikipedia: Composite material Ashby diagrams Engineering Materials and Processes

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

25. 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

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 http://www.bushmantanks.com.au/web/page/there-is-a-difference-between-tank-materials-/news/4531 Engineering Materials and Processes