Presentation on theme: "Smart materials Intelligent Structures Biomimetics John Summerscales School of Marine Science and Engineering University of Plymouth."— Presentation transcript:
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” l normal materials have limited responses l smart materials have appropriate responses l... but response is the same every time
Smart materials l 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 (material or structure ?) l Goretex ® l micro-porous expanded PTFE discovered in 1969 by Bob Gore l ~ 14 x 10 12 micropores per m². l each pore is about 700x larger than a water vapour molecule l water drop is 20,000x larger than a pore
Intelligent structures (IS) “intelligent responds to a stimulus with a calculated response and different possible actions” l composites made at low temp l can embed additional components l control can decide on novel response
Intelligent structures (IS) l embed three elements of the system: sensors signal processing and control actuators
Sensors l strain gauges l microdieletric interdigitated sensors l optical fibres l piezoelectric crystals l shape memory alloys l sensitive semiconductor chip l 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 l issues with data fusion for large sensor arrays
Control l 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 l advanced systems...
Advanced control l proportional integral derivative (PID) l fuzzy logic control (FLC) sliding mode control l artificial neural networks (ANN) l genetic algorithms (GA) l knowledge-based systems/ artificial intelligence/expert systems
Actuators l hydraulic, pneumatic and electric l piezoelectric crystals shape changes when voltage applied l shape memory materials shape changes at a specific temperature alloys = SMA.... polymers = SMP l magneto-rheological (MR) fluids viscosity changes with magnetic field l electro-rheological (ER) fluids viscosity changes with electric field
Intelligent Structures: applications l artificial hand SMA fingers controlled by nerve (myoelectric) signals l vibration damping apply electric field to ER fluid l skyscraper windows acoustic emission warning system
Biomimetics l a.k.a bionics, biognosis l 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 l gathering momentum due to the ever increasing need for sympathetic technology
Biomimetics l “inspiration rather than imitation” Janine Benyus. l “design inspired by nature” BioNIS thematic network
Biomimetics l 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™ Chobham armour vs nacre
Biomimetics l 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 l geckos to hang single-toed from sheer walls and walk along ceilings using fine hairs on feet l University of California - Berkeley created an array of synthetic micro-fibres using very high friction to support loads on smooth surfaces.
Biomimetics: Lotus effect l most efficient self-cleaning plant = great sacred lotus (Nelumbo nucifera) l mimicked in paints and other surface coatings l pipe cleaning in oil refineries (Norway) Images from http://library.thinkquest.org/27468/e/lotus.htm http://library.thinkquest.org/27468/e/lotus.htm http://www.villalachouette.de/william/lotusv2.gif http://www.villalachouette.de/william/lotusv2.gif http://www.nees.uni-bonn.de/lotus/en/vergleich.html http://www.nees.uni-bonn.de/lotus/en/vergleich.html
Biomimetics l Lotus effect self-cleaning surfaces l surface of leafwater droplet on leaf l Image from http://library.thinkquest.org/27468/e/lotus.htm
Biomimetics l 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
Â 26 http://www.rarebirdphotography.co.uk Biomimetics http://www.rarebirdphotography.co.uk Common Tern Ivory Gull Squacco Stone Curlew
Â 27 l Grumman X-29 FSW aircraft 1984 to 1992 http://www.globalsecurity.org/military/systems/aircraft/x-29.htm Aeroelastic tailoring
Hydroelastic tailoring l marine sterngear propellers composite twisted rudders for USN DDG51 class destroyers l marine renewable energy (MRE) devices image from http://d2n4wb9orp1vta.cloudfront.net/resources/images/cdn/cms/1408-a.jpg
Platelet Technology TM l Brinker Technology Platelet Technology TM l discrete particles released into pipe flow l when particles encounter modified flow at a leak, fluid forces entrain them into the leak and hold them against the pipe wall l seals and marks the position of the leak for subsequent detection. l YouTube videos: animation the technology Yorkshire Water Scottish Water animationthe technologyYorkshire WaterScottish Water
Smart-fabric l pine-cone model l adapts to changing temperatures by opening when warm or shutting tight if cold
ElekTex™ l looks and feels like a fabric l capable of electronic x-y-z sensing l fold it, scrunch it or wrap it l lightweight, durable, flexible l cost competitive l cloth keyboards and keypads details: http://www.electrotextiles.com
Nacre (abalone/mother-of-pearl) CaCO 3 aragonite crystals hexagonal platelets: 10-20 µm x 0.5 µm thick arranged in a continuous parallel lamina. layers separated by sheets of organic matrix composed of elastic biopolymers (such as chitin, lustrin and silk-like proteins). brittle platelets and thin elastic biopolymers makes the material strong and resilient due to adhesion by the "brickwork“ arrangement of the platelets which inhibits transverse crack propagation.
Nacre l Micrograph from Tomsia et al http://www.physorg.com/news10408.html l Schematic from http://en.wikipedia.org/wiki/Mother_of_pearl
Chobham armour l an arrangement of metal plates, ceramic blocks, aramid fabrics and open space ? rounds get through the outer layer ceramic material absorbs heat and impact energy aramid fabric catches debris hot gases or metal pieces spread around empty air pockets.
Acknowledgements l Various websites from which images have been extracted
To contact me: Dr John Summerscales ACMC/SMSE, Reynolds Room 008 University of Plymouth Devon PL4 8AA ) 01752.23.2650 01752.23.2638 email@example.com http://www.plymouth.ac.uk/staff/jsummerscales