SMART MATERIALS

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SMART MATERIALS




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Introduction-

• Nature is full of magic materials.
• Smart materials can sense, stimulate, process
  and actuate a response.
• the properties can be easily altered.

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Shape memory alloys (SMAs)-

• Metals which exhibit 2 unique properties
• (1) Pseudo-elasticity.
• (2) Shape Memory Effect.

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Working of SMAs-

• The properties are due to the solid state phase
  change.
• There are two phases-
• (1) Marten site and
• (2) Austenite.

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• Marten site is relatively soft and exist at low
  temps
• The molecular structure is as below

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• Austenite is the stronger phase, occurs at high
  temps.
• Cubic structure.

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Shape Memory Effect-

• The un-deformed marten site and the austenite
  have same size and shape.
• Shape memory effect is absorbed when it is cooled
  
• down to less than Mf.

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Pseudo Elasticity-

• It occurs in the alloys which completely consists
  of Austenite.
• It occurs without a change in temperature.
• Applications of pseudo elasticity
• (1) eyeglass frames.
• (2) orthodontic arches.

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Applications of shape memory alloys-

• In air craft maneuverability.

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• In Robotic muscles

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• Points of consideration-
• The method of controlling movement with the limb.
• Emulating real human movements.
• The gripping force required to hold any object.

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• Creating human motion using SMA wires is a
  complex task.
• The wire is heated by passing the current through
  it.

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• In Bone plates

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• advantages of sma-
• Bio-compact ability
• Good Mechanical properties.
• dis-advantages of sma-
• These alloys are expensive.
• poor fatigue properties

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Conclusion-

• The SMAs have a major say in the field of
  precision engineering.
• These play a vital role in the surgical
  operations.
• These act as best alternatives in the field of
  manufacturing.

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References-

• Material Science and Manufacturing
• by M.Moallem.
• Material Science and Engineering
• by K.M.Guptha, Umesh Publications.
• Elements of Material Science and Engineering
• by Van vik / Adison Wesley.

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