Modern materialsModern materials
John SummerscalesSchool of Engineering
University of Plymouth
Introduction Introduction
composite materials smart materials and intelligent structures biomimetics nano technology and MEMS opportunities
Composite materialsComposite materials
19xxs reinforced rubber tyres 1930s fibreglass 1960s carbon fibre 1970s aramid fibre 2000s smart materials
and intelligent structures
Recent composite failuresRecent composite failures Team Philips
sandwich debond Flight 587 ?
shear failure ?
Smart materialsSmart materials
normal materials have limited responses smart materials have appropriate responses ... but response is the same every time
“smart responds to a stimulus with one predictable action”
Smart materialsSmart materials
smart materials have appropriate responses photochromic glass
darkens in bright light
acoustic emission sounds emitted under high stress
optical fibres broken ends reflect light back
self-healing tyres
photochromic glass
Intelligent structures (IS)Intelligent structures (IS)
composites made at low temp can embed sensors-control-actuators control can decide on novel response
“intelligent responds to a stimulus
with a calculated response and
different possible actions”
SensorsSensors
piezoelectric crystals shape memory alloys electro-rheological fluids optical fibres
see animated image files athttp://www.spa-inc.net/smtdsmart.htm
ActuatorsActuators
hydraulic, pneumatic and electric piezoelectric crystals
shape changes when voltage applied shape memory materials
shape changes at a specific temperature electro-rheological fluids
viscosity changes with electric field
Electro-/magneto-rheological Electro-/magneto-rheological fluidsfluids
shape memory alloy
Applications for Applications for Intelligent StructuresIntelligent Structures artificial hand
SMA fingers control by nerve 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 artificial silk 3 000 years ago Daedalus' wings - early design failures
gathering momentum due to the ever increasing need for sympathetic technology
BiomimeticsBiomimetics
Notable innovations from understanding nature
Velcro Lotus effect self-cleaning surfaces drag reduction by shark skin
BiomimeticsBiomimetics
Velcro small hooks enable seed-bearing burr
to cling to tiny loops in fabric
Biomimetics: Lotus effectBiomimetics: 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
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 skin decrease drag and thusgreatly increase swimming proficiency
Airbus fuel consumption down 1½%when “shark skin” coating applied to aircraft
Image from http://www.pelagic.org/biology/scales.html
Waterproof clothing Waterproof clothing
Goretex®
micro-porous expanded PTFE discovered in 1969 by Bob Gore ~ 1.4 billion micropores per cm².
each pore is about 700x larger than a water vapour molecule
water drop is 20,000x larger than a pore
GoretexGoretex
Controlled crystal growthControlled crystal growth
Brigid Heywood Crystal Science Group at Keele
controlling the nucleation and growthof inorganic materials to make crystalline materials
Mohs hardness scaleMohs hardness scale
felspar quartz topaz carborundum diamond
talc gypsum calcite fluorite apatite
Hardness of steel about 6.5
... but what will scratch diamond?
HardnessHardness
Diamond begins to burn at 850°C Boron nitride (BN) subjected to
pressures of 6 GPa and temperatures of 1650°C produces crystals that are harder than diamond and can withstand temperatures up to about 1900°C.
Auxetic materials/structuresAuxetic materials/structures
Normal
Transverse contraction
Auxetic
Transverse expansion
Auxetic materials/structuresAuxetic materials/structures
negative Poisson’s ratio
auxetic honeycomb
NanostructuresNanostructures surface structures with feature sizes
from nanometres to micrometres white light optics limited to ~1μm use electron-beam or x-ray lithography
and chemical etching/deposition image = calcium fluoride
analog of a photoresist fromhttp://mrsec.wisc.edu/seedproj1/see1high.html
NanotubesNanotubes
Carbon 60 buckyballs (1985) graphitic sheets seamlessly wrapped
to form cylinders (Sumio Iijima, 1991) few nano-meters in diameter, yet
(presently) up to a milli-meter long Image from
http://www.rdg.ac.uk/~scsharip/tubes.htm
MEMS: micro electro MEMS: micro electro mechanical systemsmechanical systems
Microelectronics and micromachining on a silicon substrate
MEMS has enabled electrically-driven motors smaller than the diameter of a human hair to be realized
Image from http://www.memsnet.org/mems/what-is.html
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
ConclusionConclusion
more energy efficient thro’ light weight more compact thro’ miniaturisation more environment friendly
reduced failures, pollution
AcknowledgementsAcknowledgements
Various websites from whichimages have been borrowed
To contact me:To contact me: Dr John SummerscalesACMC/DMME, Smeaton Room 101
University of Plymouth
Devon PL4 8AA 01752.23.2650 01752.23.2650 [email protected] http://www.tech.plym.ac.uk/sme/jsinfo.htm