what is a smart material?
a material with a property that is altered by an external stimulus
what properties change when exposed to a stimulus? [5]
- colour
- shape
- viscosity
- volume
- conductivity
what 4 factors affect smart materials?
- temperature changes
- levels of light
- moisture
- pressure
examples of smart materials [6]
- shape memory alloys
- thermochromic pigment
- phosphorescent pigment
- photochromic pigment
- electroluminescent wire
- Piezoelectric material
what are shape memory alloys?
materials programmed to remember a specific shape
what stimuli activates SMA?
- weather
- body temperature
- electrical current
what is the most common shape memory alloy?
Nitinol [nickel and titanium
how do you program shape memory alloys?
- shaped in a jig then heated [furnace/flame/electric] above transformation temperature
- once cooled the SMA will return to its jig shape when deformed by heat
- activation temperature for reforming is dictated by materials composition
uses for shape memory alloys
- glasses frames
- orthodontic braces wire
- heat sensitive valves
what does thermochromic pigment do?
changes colour or opacity when a temperature change occurs
where can thermochromic pigment be added? [not products] [6]
- materials
- finishes
- varnishes
- paints
- dyes
- polymers
what is phosphorescent pigment?
glow in the dark material that responds to light
uses for phosphorescent pigment
fire exit signs
stickers
toys
what is photochromic pigment?
changes colour or opacity due to UV light exposure [reversible]
uses for photochromic pigment
glasses
clothes
novelty items
stationary
what is electroluminescent wire?
copper wire coated in phosphor which glows when an alternating current passes through
how is electroluminescent wire different from LED ?
produces a 360 degrees unbroken thread of light
properties of electroluminescent wire and uses?
- flexible
- used outdoors
- lighting
- accessories
- bikes
- costumes
what are piezoelectric materials?
convert mechanical energy to electrical energy and vice versa
how do piezoelectric materials work?
pressure and vibrations are converted to electrical charge which can be stored for later use
what materials are piezoelectric ?
- crystal
- ceramic
- bone
- viruses
uses for piezoelectricity?
- sparks in lighters
- trip burglar alarms
- generate sound for fire alarms
how do ultrasonic submarine detectors work?
- grid of quarts held between steel plates
- resonates when electric current is applied
- cell emits sound underwater
- terrain measured by timing the echo return
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performance of wood39
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Stock forms - wood32
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Performance of Metals35
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Polymer characteristics58
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Paper and Boards28
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Polymers36
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Elastomers29
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Biodegradable Polymers27
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Composites33
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Finishes106
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Printing Processes30
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Smart Materials23
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Digital design and manufacture76
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Modern materials21
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performance characteristics of metal24
