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ENGINEERING, AE 2024 HSC 22d

How does fibre metal laminate (FML) contribute to enhanced structural performance in aircraft?   (3 marks)

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→ FML offers several advantages over traditional aluminium alloys in aircraft construction.

→ Its key benefits include enhanced impact and fatigue resistance, better corrosion protection, and reduced weight.

→ The material’s strength comes from its directional layered construction, which can be customised for specific aircraft sections.

→ This ability to tailor FML’s properties during manufacturing makes it adaptable for various aircraft applications.

Show Worked Solution

→ FML offers several advantages over traditional aluminium alloys in aircraft construction.

→ Its key benefits include enhanced impact and fatigue resistance, better corrosion protection, and reduced weight.

→ The material’s strength comes from its directional layered construction, which can be customised for specific aircraft sections.

→ This ability to tailor FML’s properties during manufacturing makes it adaptable for various aircraft applications.

Mean mark 56%.

ENGINEERING, AE 2016 HSC 25aii

An image of a small drone is shown.
 


  

Nylon propellers are used on drones whereas carbon fibre composite propellers are used on commercial aircraft.

Describe a suitable manufacturing method for each type of propeller.   (3 marks)

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Nylon propellers

→ Injection moulded

→ A screw feeds nylon pellets into a heat chamber.

→ As the screw rotates, a combination of pressure, friction and external heat melts the nylon.

→ Molten nylon is pumped into multi-cavity moulds for setting. 
 

Carbon fibre composite propellers

→ A mould is laid with an impregnated carbon fibre sheet and placed into a vacuum bag.

→ An autoclave is used to evacuate the bag so the assembly can be heated and then allowed to set.

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Nylon propellers

→ Injection moulded

→ A screw feeds nylon pellets into a heat chamber.

→ As the screw rotates, a combination of pressure, friction and external heat melts the nylon.

→ Molten nylon is pumped into multi-cavity moulds for setting. 
 

Carbon fibre composite propellers

→ A mould is laid with an impregnated carbon fibre sheet and placed into a vacuum bag.

→ An autoclave is used to evacuate the bag so the assembly can be heated and then allowed to set.


♦♦ Mean mark 36%.

ENGINEERING, AE 2017 HSC 22b

Explain how a carbon fibre bicycle frame is manufactured.   (3 marks)

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→ A mould that is either a ‘bladder’ (deflated when frame cured) or a smooth steel mould is used.

→ Pre-impregnated carbon fibres are wrapped around the mould.

→ Fibre wrapping can utilise pre-manufactured sheets, hand laid over the mould or via roll-wrapping.

→ Alternatively, carbon fibre can be applied directly to the mould using filament-winding.

→ The frame is then put inside a pressure chamber (may be a heated autoclave) in a vacuum-proof bag.

→ A catalyst that may be UV light or heat sensitive, is then used to activate the resin.

Show Worked Solution

→ A mould that is either a ‘bladder’ (deflated when frame cured) or a smooth steel mould is used.

→ Pre-impregnated carbon fibres are wrapped around the mould.

→ Fibre wrapping can utilise pre-manufactured sheets, hand laid over the mould or via roll-wrapping.

→ Alternatively, carbon fibre can be applied directly to the mould using filament-winding.

→ The frame is then put inside a pressure chamber (may be a heated autoclave) in a vacuum-proof bag.

→ A catalyst that may be UV light or heat sensitive, is then used to activate the resin.


♦♦♦ Mean mark 23%.

ENGINEERING, PPT 2017 HSC 22a

Carbon fibre was originally developed to produce aircraft bodies and high performance vehicles. Carbon fibre is now used in a wide range of applications, including the manufacture of the type of bicycle frame shown.
 

Outline the advantages of carbon fibre bicycle frames over steel bicycle frames.   (3 marks)

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Advantages of carbon fibre bicycle frames

→ Excellent strength to weight ratio, which is a preferred feature and is superior to that of steel.

→ More intricate shapes can be moulded with carbon fibre than steel.

→ Rigid and resistant to corrosion.

→ Wide colour selection available.

Show Worked Solution

Advantages of carbon fibre bicycle frames

→ Excellent strength to weight ratio, which is a preferred feature and is superior to that of steel.

→ More intricate shapes can be moulded with carbon fibre than steel.

→ Rigid and resistant to corrosion.

→ Wide colour selection available.

ENGINEERING, AE 2019 HSC 25b

Some materials have properties that allow them to be used in the manufacture of both modern racing yachts and aircraft. These materials include Kevlar® aramid fibre, carbon fibre epoxy composites and aluminium alloys.

Complete the table by providing a property which makes each of these materials suitable for the manufacture of both yachts and aircraft.   (3 marks)
 

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Include one of the properties in the second column:

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Include one of the properties in the second column:

ENGINEERING, AE 2019 HSC 24a

An image of an aeroplane is shown with the position of the wing support beam indicated.
 

Assume the engines are supported by the single beam. The beam runs through the plane, wing tip to wing tip.

Compare the use of composite materials with the use of metals for the manufacture of the beam.   (3 marks)

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Answers could include 3 of the following comparisons:

Composite materials vs Metals 

→ Composite materials are lighter than metals.

→ Manufacture: Carbon fibre epoxy composite beams requires specialised equipment whereas metal based inputs can be manufactured using readily accessible tools such as welders, gas torches and plasma cutters.

→ Composite materials are easier to lift due to lighter weight. This allows workers to position them more easily during the construction process.

→ Equipment used for making carbon fibre epoxy moulds likely to be more accurate than in metal fabrication. However, it is possible to achieve similar accuracy in machining metals compared to that of composite materials.

→ Due to the nature of the wing support beam and the stresses placed on it, a metal beam is subject to stress weaknesses (such as scratches and corners of drilled holes) and flaws in welds that create fatigue. Carbon fibre not affected by fatigue cracking.

Show Worked Solution

Answers could include 3 of the following comparisons:

Composite materials vs Metals 

→ Composite materials are lighter than metals.

→ Manufacture: Carbon fibre epoxy composite beams requires specialised equipment whereas metal based inputs can be manufactured using readily accessible tools such as welders, gas torches and plasma cutters.

→ Composite materials are easier to lift due to lighter weight. This allows workers to position them more easily during the construction process.

→ Equipment used for making carbon fibre epoxy moulds likely to be more accurate than in metal fabrication. However, it is possible to achieve similar accuracy in machining metals compared to that of composite materials.

→ Due to the nature of the wing support beam and the stresses placed on it, a metal beam is subject to stress weaknesses (such as scratches and corners of drilled holes) and flaws in welds that create fatigue. Carbon fibre not affected by fatigue cracking.

ENGINEERING, AE 2019 HSC 15 MC

Titanium is used to manufacture aircraft undercarriages that support landing wheels.

Why is titanium used in preference to alloy steel for this purpose?

  1. It has lower density and lower strength.
  2. It has lower density and higher strength.
  3. It has higher density and lower strength.
  4. It has higher density and higher strength.
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`B`

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→ Lower density and higher strength, means the material has a very high strength to weight ratio, or specific strength.

→ This is one of the most beneficial characteristics associated with titanium alloys.

`=>B`

ENGINEERING, AE 2021 HSC 23d

Carbon fibre epoxy is an example of a composite material used in aircraft construction.

Describe the benefits of using this composite in aircraft construction in terms of both its manufacturing properties and its in-service properties.   (3 marks)

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→ Carbon fibre epoxy matrices can be formed into more complex shapes and are stronger than alternative materials. This results in an improved aircraft performance.

→ Carbon fibre is often added to resin to produce a material with higher specific strength than its predecessor. This weight loss decreases fuel consumption or allows for an increased number of passengers.

→ In-service properties of composites include non-directional strength or highly directional strength behaviour depending on the composite’s nature and layup.

Show Worked Solution

→ Carbon fibre epoxy matrices can be formed into more complex shapes and are stronger than alternative materials. This results in an improved aircraft performance.

→ Carbon fibre is often added to resin to produce a material with higher specific strength than its predecessor. This weight loss decreases fuel consumption or allows for an increased number of passengers.

→ In-service properties of composites include non-directional strength or highly directional strength behaviour depending on the composite’s nature and layup.