Intelligent Structures Biomimetics

boorishadamantAI and Robotics

Oct 29, 2013 (4 years and 14 days ago)

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Smart materials

Intelligent Structures

Biomimetics

John Summerscales

School of
Marine Science and
Engineering

University of Plymouth


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


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 10
12

micropores per m².


each pore is about 700x larger than

a water vapour molecule


water drop is 20,000x larger than a pore

Goretex:

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


Intelligent structures (IS)


embed three elements of the system:


sensors


signal processing and control


actuators

Sensors


strain gauges


microdieletric interdigitated sensors


optical fibres


piezoelectric crystals


shape memory alloys


electro
-
rheological fluids


giant magnetoimpedance (GMI) wires

Optical Fibre Bragg Grating (OFBG)

Non
-
Destructive Testing of Fibre
-
Reinforced Plastics Composites

image from http://en.wikipedia.org/wiki/Image:Fbg.GIF

Signal processing


issues with data fusion

for large sensor arrays

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 ...

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

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

shape memory alloy

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

Magneto
-
rheological (MR) fluids

Electro
-
rheological (ER) fluids


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

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

Biomimetics


“inspiration rather than imitation”


Janine Benyus.



“design inspired by nature”


BioNIS thematic network



Biomimetics


Notable innovations

from understanding nature


Velcro


Gecko tape


Lotus effect self
-
cleaning surfaces


Drag reduction by shark skin


Platelet Technology
TM

for pipe repair


Smart
-
fabric


ElekTex™

Biomimetics


Velcro


small hooks enable seed
-
bearing burr

to cling to tiny loops in fabric

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.

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

Biomimetics


Lotus effect self
-
cleaning surfaces






surface of leaf

water droplet on leaf



Image from http://library.thinkquest.org/27468/e/lotus.htm

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


26


Biomimetics

http://www.rarebirdphotography.co.uk

Common Tern Ivory Gull




Squacco Stone Curlew


27



Grumman X
-
29

FSW aircraft 1984 to 1992



http://www.globalsecurity.org/military/systems/aircraft/x
-
29.htm

Aeroelastic

tailoring

Platelet Technology
TM


Brinker Technology Platelet Technology
TM


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


Smart
-
fabric


pine
-
cone model


adapts to changing
temperatures

by opening when warm
or shutting tight if cold

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

Acknowledgements


Various websites from which

images have been extracted