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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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