Fibre-reinforced composite materials

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ENMAT101A Engineering Materials and ProcessesAssociate Degree of Applied Engineering (Renewable Energy Technologies)Lecture 24 – Fibre-reinforced composite materials


Fibre-reinforced composite materials

EMMAT101A Engineering Materials and Processes

Reference Text Section

Higgins RA & Bolton, 2410. Materials for Engineers and Technicians, 5th ed, Butterworth Heinemann

Ch 24

Reference Text Section


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).

http://woodmagic.vt.edu

http://woodmagic.vt.edu/


Fibre-reinforced composite materials (Higgins 24)


24.1.1 Man-made fibre-reinforced composites• Matrix materials, such as thermosetting or thermoplastics polymersand some low-melting point metals, reinforced with fibres of carbon,glass or organic polymer.• Polymers, usually thermosetting, reinforced with fibres or laminatesof woven textile materials.• Vehicle tyres in which vulcanised rubber is reinforced with woventextiles and steel wire.• Materials such as concrete reinforced with steel rods.


24.2 Unidirectional Composites (Higgins 24.2)


24.2.1 Relative density of composite24.2.2 Tensile strength of composite24.2.3 Modulus of composite

Higgins


24.3 Fibres (Higgins 24.3)


24.3.1 Glass fibre24.3.2 Carbon fibre24.3.3 Boron fibre24.3.4 Aramid fibre (Kevlar)24.3.5 Other fibres

Carbon Aramid (Kevlar) Glass

http://en.wikipedia.org/wiki/File:Kohlenstofffasermatte.jpg

http://en.wikipedia.org/wiki/Glass_fiber

http://en.wikipedia.org/wiki/Kevlar


24.3 Fibres (Higgins 24.3)


Higgins


24.4 Matrix materials (Higgins 24.4)


• It should be stable to a temperature at which the properties of thefibre begin to deteriorate.• It must be capable of resisting any chemical attack by itsenvironment.• It should not be affected by moisture.

24.4.1 Thermosetting resins24.4.2 Thermoplastic polymers24.4.3 Metals

http://www.glowpaint.com.au


24.5 Mechanical properties (Higgins 24.5)


Higgins


24.6 Fibre-composite manufacture (Higgins 24.6)


Higgins

• Rovings. A 'roving' of glass fibres, which may be several kilometresin length, consists of 'strands', or bundles of filaments wound on to a'creel'. A 'strand' contains some 200 filaments, each about 10 um indiameter. 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 onlyproduce composites which are anisotropic in their properties,strength being in a direction parallel to the fibre direction.

Composites manufactured as individual components. Here the fibremay be woven into a 'preform' which roughly follows the mould ordie contour. In this case, the mechanical properties will tend to bemulti-directional.




Higgins

24.6.1 Poltrusion




Fibreglass/polyester Boat Hull http://rampageous.com

24.6.2 'Hand-and-spray' placement24.6.3 Press moulding24.6.4 Resin-transfer moulding24.6.5 Metal matrix composites


24.7 Uses of fibre-reinforced composites (Higgins 24.7)


Higgins

The most important of these materials commercially are polymer matrixcomposites 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 modulusof elasticity.• Good resistance to corrosion.• Good fatigue resistance, particularly parallel to the fibre direction.


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

http://www.solaripedia.com/13/25/dangers_of_wind_power.html

http://www.solaripedia.com/13/25/dangers_of_wind_power.html


24.8 Reinforced wood (Higgins 24.8)


Higgins

The development of strong synthetic resin adhesives some years agoresulted in much progress in the use of timber as a constructionalmaterial. Also called ‘engineered wood’.

24.8.1 Laminated wood24.8.2 Plywood, blockboard and particleboard

http://en.wikipedia.org/wiki/Composite_material


24.8 Reinforced wood (Higgins 24.8)


http://www.photos-public-domain.com

24.8.3 Corrugated cardboard

Laminated boards

Complex anatomy of a carton.

Image: Carton Council


24.9 Reinforced concrete (Higgins 24.9)


Higgins

Steel reinforcing is designed to take tension, while concrete assumed to have zero tensile strength but takes compression.



http://en.wikipedia.org/wiki/File:RebarCloseup.jpg



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 ConcreteWikipedia

24.9 Reinforced concrete (Higgins 24.9)



Concrete TestHigh 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 ConcreteYou Tube

rutgerscivilengr

OfflineOnline

http://www.youtube.com/user/rutgerscivilengr

http://www.youtube.com/watch?v=WC6AgX2N1Go

http://www.youtube.com/watch?v=WC6AgX2N1Go



Resources.

Ashby diagrams

Young's modulus - DensityYoung's Modulus - CostStrength - DensityStrength - ToughnessStrength - ElongationStrength - CostStrength - Max service temperatureSpecific stiffness - Specific strengthElectrical resistivity - CostRecycle Fraction - CostEnergy content - Cost

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/stiffness-density/default.html

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/stiffness-cost/default.html

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/strength-density/default.html

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/strength-toughness/default.html

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/strength-ductility/default.html

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/strength-cost/default.html

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/strength-temp/default.html

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/spec-spec/default.html

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/resistivity-cost/default.html

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/recycling-cost/default.html

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/energy-cost/default.html

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/spec-spec/basic.html



Composite MaterialsCook, Jerome T. [US]: Society of Manufacturing Engineers, c2005. DVD (17 min.). Part A: Hand lay-up, theory, open mould chopped roving, marine, vacuum baggingPart B: Resin infusion, resin transfer, compression moulding, pultrusion, filament winding, continuous profile, bulk casting, centrifugal castingFeatures 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 620.192/COMPRecommended Viewing: All sections.

Videos

http://wsilibraries.tafensw.edu.au/mount-druitt/



Wikipedia: Fibre-reinforced plastic

Resources.

Wikipedia: Composite material

Ashby diagrams

http://en.wikipedia.org/wiki/Fibre-reinforced_plastic

http://en.wikipedia.org/wiki/Composite_material

http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/spec-spec/basic.html


Glossary


AnisotropicChopped fibreRovingsUnidirectionalWoven matChopped strand matFilament woundMatrixPoltrusionAramidCarbon fibre


QUESTIONSHiggins Ch24, Newell, Timmings, Sheedy, Callister, Ashby

1. Define all glossary terms2. 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.

3. 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.

4. Give five reasons for a particle to be added to a matrix – include a range of different types of particle composites.

5. Explain how small particles can strengthen a ductile metal matrix even when the particles are rounded. (Dispersion hardened material).

6. 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.

7. Explain why fibres are available in woven mat, chopped strand mat and filament. Give examples of each.

8. Polyester is common with glass and epoxy with carbon. Give reasons. Give advantages and disadvantages of each matrix resin.



QUESTIONS: Fibre CompositesHiggins Ch24, Newell, Timmings, Sheedy, Callister, Ashby

9. Compare and contrast the advantages and limitations of the following systems of reinforcing concrete: (a) simple reinforcement, (b) prestressed reinforcement, (c) post-tensioned reinforcement.

10.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.

11. 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


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




Fibre-reinforced composite materials

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