DT Modern and Smart Materials 1.1

Modern
1. Fibre optics
  1. transmit light as a digital signal (in pulses)
  2. more data can be sent because each glass fibre in the cable can carry data
2. Liquid Crystal Displays (LCD)
  1. allow light to pass through when aligned 'naturally''; when a small voltage is applied the path of the electron flow changes, blocking light
  2. reflective or backlit
  3. e.g. calculator displays, TV screens
3. Kevlar
  1. has 5x the strength-to-weight ratio of steel
  2. fibres are woven together flat
  3. used for bulletproof vests
  4. Nomex (a deriavtive) protects against heat and is worn by racing drivers
4. Carbon fibre
  1. made up of carbon woven into a cloth, impregnatted with resin to hold them together
  2. very lightweight
  3. high strength
  4. often used in F1 racing and sports equipment
5. Polymorph
  1. a low melt polymer (60˚c) which can be remoulded easily
6. Man made boards
  1. Flexible MDF
    1. thin grooves cut into the material, allowing it to bend
    2. usually the grooves cannot be seen as they are inside
    3. only able to bend at 90˚ to the grooves
  2. Flexi ply
    1. as with ordinary plywood, there is an odd number of layers - usually 3
    2. two outer layers are open grained, and are much thicker than the core
    3. direction of grain determines direction of curvature
    4. expensive
    5. used for aesthetics and on furnitiure
Smart
1. Thermochromic pigments
  1. Change colour in response to heat
2. Phosphorescent pigments
  1. absorb light and then release the light energy over a period of time
  2. e.g. emergency warning signs, 24hr clock faces
3. Shape memory alloys
  1. e.g. nitinol wire
    1. shrinks in length by 5% when an electrical current is passed through it
  2. e.g. stent
    1. bio-engineering - it shrinks when chilled, so when placed into a blocked/collapsed artery it returns to its original size
  3. e.g. memoflex glasses
    1. nickel/titanium alloy which will return to its original shape at room temperature after being deformed. A 'superelastic' alloy
4. Piezoelectric devices
  1. Produce an electrical signal when compressed
  2. e.g. sensors on bridges - will produce a signal when the load is above a certain amount
5. Quantum tunnelling composites
  1. change from an insulator to a conductor when a deliberate force is applied
    1. e.g. touch sensitive clothing

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DT Modern and Smart Materials 1.1

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	Created by Niamh Walsh over 9 years ago

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