Smart materials Intelligent Structures Biomimetics John Summerscales School

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”

Smart materials . pptx has additional video normal materials have limited responses l smart materials have appropriate responses l. . . but response is the same every time l

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 ? ) Goretex® l micro-porous expanded PTFE discovered in 1969 by Bob Gore l ~ 14 x 1012 micropores per m². l each pore is about 700 x larger than a water vapour molecule l water drop is 20, 000 x larger than a pore l

Goretex:

Intelligent structures “the definition of insanity is doing something over and over again and expecting a different result” l … variously attributed to Albert Einstein, Benjamin Franklin and Mark Twain l “intelligent responds to a stimulus with a calculated response and different possible actions”

Intelligent structures (IS) composites made at low temp l can embed additional components l control can decide on novel response l

Intelligent structures (IS) l embed three elements of the system: § sensors § signal processing and control § actuators

Sensors 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 l

Optical Fibre Bragg Grating (OFBG) image from http: //en. wikipedia. org/wiki/Image: Fbg. GIF Non-Destructive Testing of Fibre-Reinforced Plastics Composites

OFBG applications l Maltese Falcon superyacht § CFRP 57 m masts with CFRP yards § OFBG report and to bridge l West Mill Bridge (Oxfordshire, 2002) § ASSET pultrusions § OFBG/PZT 250 scans/s

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 proportional integral derivative (PID) l fuzzy logic control (FLC) l § sliding mode control artificial neural networks (ANN) l genetic algorithms (GA) l knowledge-based systems/ artificial intelligence/expert systems l

Actuators hydraulic, pneumatic and electric l piezoelectric crystals l § 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

shape memory alloy http: //sirius. mtm. kuleuven. be/Research/ADAPT/Video/05 -11_11 -05_1. avi

Magneto-rheological (MR) fluids Electro-rheological (ER) fluids

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 § lucky guy survives accident in Riyadh (video)

Biomimetics l also known as § bionics § biognosis § synthetic biology

Biomimetics l the concept of taking ideas from nature to implement in another technology § Chinese silk cultivation begins c. 4000 BC • 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 “inspiration rather than imitation” Janine Benyus. l “design inspired by nature” Bio. NIS thematic network l

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 Elek. Tex™ 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 l 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 l Lotus effect self-cleaning surfaces l surface of leaf l Image from http: //library. thinkquest. org/27468/e/lotus. htm water droplet on leaf

Biomimetics: Lotus effect l l l 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 v http: //library. thinkquest. org/27468/e/lotus. htm v http: //www. villalachouette. de/william/lotusv 2. gif v http: //www. nees. uni-bonn. de/lotus/en/vergleich. html

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

Biomimetics http: //www. rarebirdphotography. co. uk Common Tern Ivory Gull Squacco Stone Curlew 30

Aeroelastic tailoring l Grumman X-29 FSW aircraft 1984 to 1992 http: //www. globalsecurity. org/military/systems/aircraft/x-29. htm 31

Hydroelastic tailoring l marine sterngear § propellers § composite twisted rudders for USN DDG 51 class destroyers l marine renewable energy (MRE) devices image from http: //d 2 n 4 wb 9 orp 1 vta. cloudfront. net/resources/images/cdn/cms/1408 -a. jpg

Platelet Technology. TM 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 l You. Tube videos: § animation the technology Yorkshire Water Scottish Water

Nacre (abalone/mother-of-pearl) • Ca. CO 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 l Micrograph from Tomsia et al http: //www. physorg. com/news 10408. html 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.

Smart-fabric pine-cone model l adapts to changing temperatures by opening when warm or shutting tight if cold l

Elek. Tex™ 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

Summary l smart materials § same response for same stimulus l intelligent structures § sensor > control > actuator § adaptive response for same stimulus l biomimetics § nature as inspiration for innovative design

Acknowledgements l Various websites from which images have been extracted