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Smart materials Intelligent Structures Biomimetics John Summerscales School of Marine Science and Engineering University of Plymouth.

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Presentation on theme: "Smart materials Intelligent Structures Biomimetics John Summerscales School of Marine Science and Engineering University of Plymouth."— Presentation transcript:

1 Smart materials Intelligent Structures Biomimetics John Summerscales School of Marine Science and Engineering University of Plymouth

2 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

3 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

4 photochromic glass

5 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

6 Goretex:

7 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

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

9 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

10 Optical Fibre Bragg Grating (OFBG) Non-Destructive Testing of Fibre-Reinforced Plastics Composites image from

11 Signal processing l issues with data fusion for large sensor arrays

12 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...

13 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

14 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

15 shape memory alloy

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

17 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

18 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

19 Biomimetics l “inspiration rather than imitation” Janine Benyus. l “design inspired by nature” BioNIS thematic network

20 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

21 Biomimetics l Velcro  small hooks enable seed-bearing burr to cling to tiny loops in fabric

22 Gecko tape image from 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.

23 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   

24 Biomimetics l Lotus effect self-cleaning surfaces l surface of leafwater droplet on leaf l Image from

25 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

26 Â 26 Biomimetics Common Tern Ivory Gull Squacco Stone Curlew

27 Â 27 l Grumman X-29 FSW aircraft 1984 to 1992 Aeroelastic tailoring

28 Hydroelastic tailoring l marine sterngear  propellers  composite twisted rudders for USN DDG51 class destroyers l marine renewable energy (MRE) devices image from

29 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

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

31 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:

32 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.

33 Nacre l Micrograph from Tomsia et al l Schematic from

34 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.

35 Acknowledgements l Various websites from which images have been extracted

36 To contact me: Dr John Summerscales  ACMC/SMSE, Reynolds Room 008 University of Plymouth Devon PL4 8AA ) 01752.23.2650  01752.23.2638  

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