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Presentation by,
POOJA HEGDEUSN: 1MV10ECO70
Sir M. Viswesvaraiah Institute of Tech.
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OVERVIEW
Introduction
Types of Smart Materials and theirapplications.
Limitations
Future Scope
Conclusion
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INTRODUCTION
What are smart materials?
Smart materials are those whose one ormore physical properties can be
dramatically altered. These propertiescan be viscosity, volume, conductivityetc.The property that can be altereddecides the application that particular
metal can be used for. A variety of smartmaterials already exist and are beingresearched extensively.
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TYPES OF SMARTMATERIALS Piezoelectric materials
Electro-rheostatic and magnetorheostatic materials
Shape memory alloys
pH sensitive polymers
Photomechanical materials and
Chromogenic systems.
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PIEZOELECTRICMATERIALS
Piezoelectric materials are those which give an
electric discharge on application of an externaldeforming force OR experience change in size
due to passage of current through them.
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APPLICATIONS
They are mostly used as sensors indifferent environment. Ex: Airbagsensors in cars.
They are often used to measure fluiddensity, fluid viscosity, fluidcompositions, force of an impact etc.
They are specially used in EnergyHarvesting from Vibrations.
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Energy Harvesting fromVibrations
Unused power exists in various forms such asmachine vibration, flowing water, wind, humanmotion and shock waves. In recent years, industrialand academic research units have focused theirattention on harvesting energy from vibrations using
piezoelectric transducers. These can be used toharvest energy for low power devices as often foundin portable electronics, sensor controlled andcondition monitoring systems due to their highadaptability and wide frequency range. They useMFC(Macro Fiber Composite) which isnt as brittle as
monolithic piezo materials. This has made a newclass of electronics possible that is battery free,autonomous devices functioning solely on harvestingmechanical vibrations with piezoelectric components.
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Applications of MFC Vibrationharvester. Non resonant energy
harvester
Autonomous dataacquisition systems
Structural healthmonitoring
Pedometers, bio datamonitoring.
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Electro-rheostatic andMagneto-rheostatic materials
Electro-rheostatic (ER) and magneto-rheostatic (MR) materials are fluids,which can experience a dramatic
change in their viscosity. MR fluidsexperience a viscosity change whenexposed to a magnetic field, while ERfluids experience similar changes in an
electric field. The composition of eachtype of smart fluid varies widely.
Ex: Iron particles in oil, cornstarch etc.
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Applications of MR and ERfluids MR fluids are used in
car shocks , dampingwashing machinevibrations, prostheticlimbs, exercise
equipment and surfacepolishing of machineparts.
ER fluids have mainlybeen developed for usein clutches and valves,
as well as enginemounts designed toreduce noise andvibration in vehicles.
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SHAPE MEMORY ALLOYS
Shape memory alloys are metals which exhibit two veryunique properties pseudo-elasticity and shape memoryeffect. The most effective and widely used alloys includeNiTi (Nickel - Titanium), CuZnAl, and CuAlNi. They exist
in two distinct solid forms. The low temperature form iscalled Martensite and a high temperature form calledAustenite.
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PROPERTIES OF SHAPEMEMORY ALLOYS
Pseudo elasticity, sometimes called superelasticity, is an elastic (reversible) response to anapplied stress, caused by a phase transformationbetween the austenitic and martensitic phases of acrystal. There is no bond stretching or introductionof defects in the crystal. Thus , a pseudo- elasticmaterial can return to its original shape even after
removal of relatively high applied strains. This iscalled shape memory effect.
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APPLICATIONS
Shape memory alloys are implemented in:
Coffee pots
Space shuttles
Thermostats
Vascular stents
Hydraulic fittings for airplanes.
They are bio- compatible, have goodmechanical properties like strength,corrosion resistance etc.
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pH SENSITIVE POLYMERS
pH sensitive or pH responsive polymersare materials which will respond to thechanges in the pH of the surroundingmedium by varying their dimensions. Suchmaterials swell or collapse depending onthe pH of their environment. There are twokinds of ph sensitive materials: one whichhave acidic group (-COOH, -SO3H) and
swell in basic pH, and others which havebasic groups (-NH2) and swell in acidic pH.
Ex: Polyacrylic acid, chitosan etc.
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APPLICATIONS
They are used in drug delivery systemsand biomimetics.
PHOTOMECHANICAL
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PHOTOMECHANICALMATERIALS AND
CHROMOGENIC SYSTEMSPhotomechanical materials show change in theshape of a material when it is exposed to light.Chromogenic materials change colour in
response to electrical, optical or thermal changes.These include electro chromic materials, which
change their colour or opacity on the application of avoltage (e.g. liquid crystal displays), thermochromic materials change in colour depending ontheir temperature, and photo chromic materials,which change colour in response to lightforexample, light sensitive sunglasses.
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APPLICATIONS
Chromogenic smartsystems are used in:
Electrochromic smart
windows Photonic hydrogen
detection
Light sensitivesunglasses etc.
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LIMITATIONS
Piezoelectric materials are brittle due the crystallinestructure. They produce relatively small strains andcannot withstand high shear and tension. They canbecome depolarized under very high voltages,temperatures and large stresses.
Shape memory alloys have slow reaction time andlow energy efficiency conversion. They areunweldable and expensive for large scale products.
Most smart materials are expensive and areequipment intensive which makes their usage quite
complicated.
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FUTURE SCOPE
They have extensive usage range from aircraftindustry to medicine to day to day usage.
They reduce space and power consumption.
They can also be used in civil structuresystems, morphing systems, compositestructures, flexible robotic systems, activenoise control, adaptive optics, active vibrationcontrol, active noise suppression , active
damping control, structural health monitoring,damage detection, mitigation and life cycledetection.
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