Smart materialsIntelligent StructuresBiomimeticsJohn SummerscalesSchool of Marine Science and EngineeringUniversity 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 1012 micropores per m². each pore is about 700x larger than a water vapour molecule 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” 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
Optical Fibre Bragg Grating (OFBG) image from http://en.wikipedia.org/wiki/Image:Fbg.GIFNon-Destructive Testing of Fibre-Reinforced Plastics Composites
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
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 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
Biomimeticshttp://www.rarebirdphotography.co.ukCommon Tern Ivory GullSquacco Stone Curlew 26
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
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
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