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thermal engineering notes by nptel
Lecture Overview
• What are “composites”?
• Importance and areas of application
• Classification
• Advantages of fiber‐reinforced composites
What are “composites”?
• Composite: Two or more chemically different constituents combined macroscopically to yield a useful material material.
• Examples of naturally occurring composites
– Wood: Cellulose Cellulose fibers bound by lignin matrix
– Bone: Stiff mineral “fibers” in a soft organic matrix permeated permeated with holes filled with liquids liquids
– Granite: Granular composite of quartz, feldspar, and mica
What are “composites composites ?”
• Some examples of man‐made composites
– Concrete: Particulate composite of agg g re ates (limestone or granite), sand, cement and water
– Plywood: Plywood: Several Several layers of wood veneer glued together
– Fiberglass: Fiberglass: Plastic Plastic matrix reinforced reinforced by glass fibers
– Cemets: Ceramic and metal composites
– Fibrous composites: Variety of fibers (glass, kevlar,
graphite, nylon, etc.) bound together by a polymeric matrix
These are not composites! composites!
• Plastics: Even though they may have several “fillers”, their presence does not alter the physical properties significantly.
• Alloys: Alloys: Here the alloy is not macroscopically macroscopically heterogeneous, especially in terms of physical properties.
• Metals with impurities: impurities: The presence presence of impurities does not significantly alter physical properties of the metal.
Where are composites composites used?
• Automotive industry: Lighter, stronger, wear resistance, rust‐free, aesthetics
– Car body
– Brake pads
– Drive shafts
– Fuel tanks
– Hoods
– Spoilers
Where are composites composites used?
• Aerospace: Lighter, stronger, temperature resistance, smart structures, wear resistance– Aircraft: Nose, doors, struts, trunnion, fairings,cowlings, cowlings, ailerons, ailerons, outboard outboard and inboard inboard flaps,stabilizers, elevators, rudders, fin tips, spoilers,edges
– Rockets & missiles: Nose, body, pressure tanks,frame, fuel tanks, turbo‐motor stators stators, etc.
– Satellites: Antennae, frames, structural parts
Where are composites composites used?
• Sports: Lighter, stronger, toughness, better aesthetics, higher damp g in p p ro erties
– Tennis
– Bicycles
– Badminton
– Boats
– Hockey
– Golfing
– Motorcycles
Where are composites composites used?
• Transportation & Infrastructure: Lighter,stronger, toughness, damp g in
– Railway coaches
– Bridges
– Ships and boats
– Dams
– Truck bodies and floors
– RV bodies
Where are composites composites used?
• And many more industry sectors
– Biomedical industry
– Consumer goods
– Agricultural equipment
– Heavy machinery
– Computers
– Healthcare