20-12-2012, 11:52 AM
Smart materials Intelligent Structures Biomimetics
Smart materials.pptx (Size: 2.11 MB / Downloads: 89)
Smart materials
“smart responds to a stimulus with one predictable action”
normal materials have limited responses
smart materials have appropriate responses
... but response is the same every time
smart materials have appropriate responses
photochromic glass
darkens in bright light
low melting point wax in a fire sprinkler
blocks the nozzle until it gets hot
acoustic emission
sounds emitted under high stress
embedded optical fibres
broken ends reflect light back
microporous breathable fabrics
Waterproof clothing
Goretex®
micro-porous expanded PTFE discovered in 1969 by Bob Gore
~ 14 x 1012 micropores per m².
each pore is about 700x larger thana water vapour molecule
water drop is 20,000x larger than a pore
Intelligent structures (IS)
“intelligent responds to a stimulus
with a calculated response and
different possible actions”
composites made at low temp
can embed additional components
control can decide on novel response
Sensors
strain gauges
microdieletric interdigitated sensors
optical fibres
piezoelectric crystals
shape memory alloys
electro-rheological fluids
giant magnetoimpedance (GMI) wires
Control
proportional integral derivative (PID)
proportional:output = (gain x error) + bias
integral:output = gain x (error + ∫error w.r.t. time)
derivative:output = gain x derivative x de/dt
advanced systems ...
Actuators
hydraulic, pneumatic and electric
piezoelectric crystals
shape changes when voltage applied
shape memory materials
shape changes at a specific temperature
alloys = SMA .. polymers = SMP
magneto-rheological (MR) fluids
viscosity changes with magnetic field
electro-rheological (ER) fluids
viscosity changes with electric field
Biomimetics
a.k.a bionics, biognosis
the concept of taking ideas from nature to implement in another technology
Chinese silk cultivation begins c.4000BC
Colin Thubron, Shadow of the Silk Road, Chatto & Windus, 2006.
Daedalus' wings - early design failures
gathering momentum due to theever increasing need for sympathetic technology
Platelet TechnologyTM
Brinker Technology Platelet TechnologyTM
discrete particles released into pipe flow
when particles encounter modified flowat a leak, fluid forces entrain them intothe leak and hold them against the pipe wall
seals and marks the positionof the leak for subsequent detection.