1. Smart materials
Intelligent Structures
Biomimetics
John Summerscales
School of Marine Science and Engineering
University of Plymouth

2. 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

3. 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

4. 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 than
a water vapour molecule
 water drop is 20,000x larger than a pore

5. Goretex:

6. 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

7. Intelligent structures (IS)
 embed three elements of the system:
 sensors
 signal processing and control
 actuators

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

9. Optical Fibre Bragg Grating (OFBG)
image from http://en.wikipedia.org/wiki/Image:Fbg.GIF
Non-Destructive Testing of Fibre-Reinforced Plastics Composites

10. Signal processing
 issues with data fusion
for large sensor arrays

11. 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 ...

12. 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

13. 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

14. shape memory alloy
http://www.mtm.kuleuven.ac.be/Research/ADAPT/Video/05-11_11-05_1.avi

15. Magneto-rheological (MR) fluids
Electro-rheological (ER) fluids

16. Intelligent Structures: applications
 artificial hand
 SMA fingers controlled by
nerve (myoelectric) signals
 vibration damping
 apply electric field to ER fluid
 skyscraper windows
 acoustic emission warning system

17. 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 the
ever increasing need for
sympathetic technology

18. Biomimetics
 “inspiration rather than imitation”
Janine Benyus.
 “design inspired by nature”
BioNIS thematic network

19. 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™

20. Biomimetics
 Velcro
 small hooks enable seed-bearing burr
to cling to tiny loops in fabric

21. Gecko tape
image from
http://www.netcomposites.com/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-fibres
using very high friction
to support loads on smooth surfaces.

22. Biomimetics: Lotus effect
 most efficient self-cleaning plant
= great sacred lotus
(Nelumbo nucifera)
 mimicked in paints and
other 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.html

23. Biomimetics
 Lotus effect self-cleaning surfaces
 surface of leaf water droplet on leaf
 Image from http://library.thinkquest.org/27468/e/lotus.htm

24. Biomimetics
 drag reduction by shark skin
 special alignment and grooved structure
of tooth-like scales embedded in shark skin
decrease drag and thus
greatly increase swimming proficiency
 Airbus fuel consumption down 1½%
when “shark skin” coating applied to aircraft
o Image from http://www.pelagic.org/biology/scales.html

25. Biomimetics
http://www.rarebirdphotography.co.uk
Common Tern Ivory Gull
Squacco Stone Curlew
26

26. Aeroelastic tailoring
 Grumman X-29
FSW aircraft 1984 to 1992
http://www.globalsecurity.org/military/systems/aircraft/x-29.htm
27

27. Platelet TechnologyTM
 Brinker Technology Platelet TechnologyTM
 discrete particles released into pipe flow
 when particles encounter modified flow
at a leak, fluid forces entrain them into
the leak and hold them against the pipe wall
 seals and marks the position
of the leak for subsequent detection.
 YouTube videos:
 animation the technology Yorkshire Water Scottish Water

28. Smart-fabric
 pine-cone model
 adapts to changing
temperatures
by opening when warm
or shutting tight if cold

29. 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

30. Acknowledgements
 Various websites from which
images have been extracted