Smart materialsSmart materialsIntelligent StructuresIntelligent StructuresBiomimeticsBiomimetics

John SummerscalesSchool of Engineering

University of Plymouth

Smart materialsSmart 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 materialsSmart 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

photochromic glass

Waterproof clothing 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

Goretex:Goretex:

Intelligent structures (IS)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)Intelligent structures (IS)

embed three elements of the system: sensorssensors signal processing and controlsignal processing and control actuatorsactuators

SensorsSensors

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

Signal processingSignal processing

issues with data fusionfor large sensor arrays

ControlControl 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 controlAdvanced 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

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

Magneto-rheological (MR) fluidsMagneto-rheological (MR) fluidsElectro-rheological (ER) fluidsElectro-rheological (ER) fluids

Intelligent Structures: Intelligent Structures: applicationsapplications

artificial hand SMA fingers controlled by

nerve (myoelectric) signals vibration damping

apply electric field to ER fluid skyscraper windows

acoustic emission warning system

BiomimeticsBiomimetics 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

BiomimeticsBiomimetics

“inspiration rather than imitation”Janine Benyus.

“design inspired by nature”BioNIS thematic network 

BiomimeticsBiomimetics 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™

BiomimeticsBiomimetics

Velcro small hooks enable seed-bearing burr

to cling to tiny loops in fabric

Gecko tapeGecko tape

image fromimage fromhttp://www.netcomposites.com/news.asp?3922http://www.netcomposites.com/news.asp?3922

Inspiration from the remarkable hairs that allow geckos to hang single-toed from sheer walls and walk along ceilings

researchers at the University of California - Berkeley, created an array of synthetic micro-fibres that uses very high frictionto support loads on smooth surfaces.

Biomimetics: Lotus effectBiomimetics: 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.html

BiomimeticsBiomimetics

Lotus effect self-cleaning surfaces

surface of leaf water droplet on leaf

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

BiomimeticsBiomimetics

drag reduction by shark skin special alignment and grooved structure

of tooth-like scales embedded in shark skindecrease drag and thusgreatly 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

Platelet TechnologyPlatelet TechnologyTMTM

Brinker Technology Platelet TechnologyTM

discrete particles released into pressurised 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.

animation: from http://www.brinker-technology.com/popup.html

video: from http://www.brinker-technology.com/video/3leak.wmv

Smart-fabricSmart-fabric

pine-cone model adapts to changing

temperaturesby opening when warm or shutting tight if cold

ElekTex™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

AcknowledgementsAcknowledgements

Various websites from whichimages have been extracted

To contact me:To contact me: Dr John SummerscalesACMC/SOE, Reynolds Room 008

University of Plymouth

Devon PL4 8AA 01752.23.2650 01752.23.2638 jsummerscales@plymouth.ac.uk http://www.plym.ac.uk/staff/jsummerscales