Smart materials Intelligent Structures Biomimetics

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Smart materialsIntelligent StructuresBiomimetics

• John Summerscales
• School of Marine Science and Engineering
• University of Plymouth

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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

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Smart materials

• 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

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photochromic glass
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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

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Goretex
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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

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Intelligent structures (IS)

• embed three elements of the system
• sensors
• signal processing and control
• actuators

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Sensors

• strain gauges
• microdieletric interdigitated sensors
• optical fibres
• piezoelectric crystals
• shape memory alloys
• electro-rheological fluids
• giant magnetoimpedance (GMI) wires

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Optical Fibre Bragg Grating (OFBG)
image from http//en.wikipedia.org/wiki/ImageFbg.
GIF
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Signal processing

• issues with data fusionfor large sensor arrays

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Control

• proportional integral derivative (PID)
• proportionaloutput (gain x error) bias
• integraloutput gain x (error ?error w.r.t.
  time)
• derivativeoutput gain x derivative x de/dt
• advanced systems ...

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Advanced control

• proportional integral derivative (PID)
• fuzzy logic control (FLC)
• sliding mode control
• artificial neural networks (ANN)
• genetic algorithms (GA)
• knowledge-based systems/artificial
  intelligence/expert systems

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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

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shape memory alloy http//www.mtm.kuleuven.ac.be/R
esearch/ADAPT/Video/05-11_11-05_1.avi
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Magneto-rheological (MR) fluidsElectro-rheologica
l (ER) fluids
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Intelligent Structures applications

• artificial hand
• SMA fingers controlled bynerve (myoelectric)
  signals
• vibration damping
• apply electric field to ER fluid
• skyscraper windows
• acoustic emission warning system

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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

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Biomimetics

• inspiration rather than imitation Janine
  Benyus.
• design inspired by nature BioNIS thematic
  network 

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Biomimetics

• Notable innovations from understanding nature
• Velcro
• Gecko tape
• Lotus effect self-cleaning surfaces
• Drag reduction by shark skin
• Platelet TechnologyTM for pipe repair
• Smart-fabric
• ElekTex

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Biomimetics

• Velcro
• small hooks enable seed-bearing burrto cling to
  tiny loops in fabric

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Gecko tapeimage fromhttp//www.netcomposites.c
om/news.asp?3922

• geckos to hang single-toed from sheer walls and
  walk along ceilings using fine hairs on feet
• University of California - Berkeley created an
  array of synthetic micro-fibresusing very high
  friction to support loads on smooth surfaces.

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Biomimetics Lotus effect

• most efficient self-cleaning plant great sacred
  lotus (Nelumbo nucifera)
• mimicked in paints andother surface coatings
• pipe cleaning in oil refineries (Norway)
• Images from
• http//library.thinkquest.org/27468/e/lotus.htm
• http//www.villalachouette.de/william/lotusv2.gif
• http//www.nees.uni-bonn.de/lotus/en/vergleich.htm
  l

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Biomimetics

• Lotus effect self-cleaning surfaces
• surface of leaf water droplet on leaf
• Image from http//library.thinkquest.org/27468/e/l
  otus.htm

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Biomimetics

• drag reduction by shark skin
• special alignment and grooved structureof
  tooth-like scales embedded in shark skindecrease
  drag and thusgreatly increase swimming
  proficiency
• Airbus fuel consumption down 1½when shark
  skin coating applied to aircraft
• Image from http//www.pelagic.org/biology/scales.
  html

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Biomimeticshttp//www.rarebirdphotography.co.uk

• Common Tern Ivory Gull
• Squacco Stone Curlew

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Aeroelastic tailoring

• Grumman X-29FSW aircraft 1984 to 1992
• http//www.globalsecurity.org/military/systems/a
  ircraft/x-29.htm

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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.
• YouTube videos
• animation the technology Yorkshire Water
  Scottish Water

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Smart-fabric

• pine-cone model
• adapts to changing temperaturesby opening when
  warm or shutting tight if cold

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ElekTex

• looks and feels like a fabric
• capable of electronic x-y-z sensing
• fold it, scrunch it or wrap it
• lightweight, durable, flexible
• cost competitive
• cloth keyboards and keypads
• details http//www.electrotextiles.com

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Acknowledgements

• Various websites from whichimages have been
  extracted

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To contact me

• Dr John Summerscales
• ACMC/SMSE, Reynolds Room 008
• University of Plymouth
• Devon PL4 8AA
• 01752.23.2650
• 01752.23.2638
• jsummerscales_at_plymouth.ac.uk
• http//www.plymouth.ac.uk/staff/jsummerscales