WHY COMPOSITE MATERIALS ARE USED IN DESIGNING THE AIRCRAFT STRUCTURE?

IN THIS POST I WILL DISCUSS INTERESTING PROPERTY ABOUT COMPOSITE MATERIALS!!
With what material the aircraft structure was built before composite material? WOOD, ALUMINIUM, TITANIUM, STEEL, AND THEIR ALLOYS ARE USED.
The key thing always should be remembered while designing is 'STRENGTH TO WEIGHT RATIO' 
while designing the aircraft.

Now to gain this property,'COMPOSITE MATERIAL' comes into the picture.

WHAT IS COMPOSITE MATERIAL?

Composite materials are high in strength to weight ratio(means strength should be more and weight should be less). Composites are a combination of two or more constituent materials with significantly different physical and chemical properties. When two or more materials combine it give other material which is completely different individual materials.

One Common Example is

Sand+Stones+Cement+Iron= Concrete Pillar.(while construction of building).

• Why aviation industry use composite materials?
• High strength to weight ratio
• High tensile strength and resistance to compression
• Saves Fuel consumption
• Improve the efficiency and performance of aircraft.

• First commercial aircraft which used composite materials?

Boeing 787 Dreamliner is the first commercial aircraft whose major structural components are made up of composites rather than aluminium alloys. Boeing 787 Dreamliner is going to use carbon laminates and carbon sandwich composites.

• The types of aircraft composite materials?

Aircraft structure mainly includes carbon laminates,glass fibers,Kevlar fiber.

• Testing of composite materials.
• the mechanical stress test will be done on composite material before designing the structure.
• Hydraulic machines are used to bend and twist composite material structures to check the worst expected conditions in real fights.

•  Properties of composite materials
• Composites have fairly very low electrical conductivity. That’s why a copper mesh is always integrated in aerospace laminates.to protect aircraft from lightning strike damage.
• Composites have relatively low thermal conductivity and thermal expansion coefficients in and out of the aircraft.
• Composites have a high strength to weight ratio, which is crucial for aircraft design.
• Composites are very damaging most tolerant.
• Composites are not very resistant to mechanical wear effects. That’s why External surfaces are treated with specific paints.

•  Advantages 
• Composites reduced the overall structural member weight by 20-50%.
• Composites are very corrosion and fatigue resistance.
• Composites have tolerable mechanical properties.
• Composites have lower assembly costs because it requires very few fasteners, bolts etc..
•  DISADVANTAGE
• Composites have higher material costs.
• Composites have very expensive repairs and maintenance.

• Future aircraft composite materials

Ceramic Matrix Composites:

                         This type of lightweight, high temperature composite materials is in the research process at  NASA for use in aircraft parts.

Spider Silk Fibers:

This future composite exhibits high ductility, allowing stretching of a fire up to 140% of its normal length. This is also under research process.

Hybrid Composite Steel Sheets

This future composite material can be stainless steel constructed with inspiration from composites and Nano tech fibers and plywood. This is again under research process.

   

Lastly there are some limitations of composites. Scientists are doing deep research on more advance composites which should be biodegradable, low recurring costs and easily available.

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