SMART MATERIALS SMART MATERIALS AND AND

STRUCTURES STRUCTURES

Presented by:Presented by:

SNEHAL PRASOONSNEHAL PRASOON

CONTENTSCONTENTS Introduction Introduction Smart MaterialsSmart Materials New Material RequirementsNew Material Requirements Classification Of Smart Materials Classification Of Smart Materials Properties Of Shape Memory AlloysProperties Of Shape Memory Alloys Smart StructureSmart Structure Components of Smart structureComponents of Smart structure Sensors and ActuatorsSensors and Actuators Structural Uses of SMA’SStructural Uses of SMA’S Case Study Case Study Conclusion Conclusion ReferencesReferences

INTRODUCTIONINTRODUCTION

Smart materials and structures technology represents an Smart materials and structures technology represents an

emerging field of study that is finding many applications emerging field of study that is finding many applications

in support of civil infrastructure systems.in support of civil infrastructure systems.

The potential benefit of this technology may be improved The potential benefit of this technology may be improved

system reliability, longevity enhanced system performance, system reliability, longevity enhanced system performance,

improved safety against natural hazards and vibrations, and a improved safety against natural hazards and vibrations, and a

reduction in life cycle costs in operating and managing civil reduction in life cycle costs in operating and managing civil

infrastructure systems. infrastructure systems.

SMARTSMART MATERIALSMATERIALS

Smart materials are materials that have the intrinsic and extrinsic capabilities , firstly to respond to stimuli and environmental changes and secondly to activate their functions according to these changes.

Depending on changes in some external conditions, "smart" materials change either their properties (mechanical, electrical, appearance), their structure or composition, or their functions.

REQUIREMENTSREQUIREMENTS

Technical properties Technological properties Economic criteria Environmental characteristics Sustainable development criteria, implying

reuse and recycling capacities.

CLASSIFICATION OF SMART MATERIALSCLASSIFICATION OF SMART MATERIALS

Actuator materials Piezoelectric Electrostrictive Magnetostrictive Shape Memory Alloys

The Sensors Optical fibers

PROPERTIES OF SMA’SPROPERTIES OF SMA’S

Repeated absorption of large amount of strain energy.

Usable strain range of 70%. Extraordinary fatigue resistance under large

strain cycle Their great durability and reliability in the

long run

SHAPE MEMORY ALLOYSSHAPE MEMORY ALLOYS

SHAPE MEMORY ALLOYSSHAPE MEMORY ALLOYS

SHAPE MEMORY ALLOYSSHAPE MEMORY ALLOYS

COMPONENTS OF A SMART STRUCTURESCOMPONENTS OF A SMART STRUCTURES

DATA ACQUISITION Collection of raw data required for appropriate sensing and monitoring of the structure.

DATA TRANSMISSION Forwards raw data to the local/central command and control units.

COMMAND AND CONTROL PROCESS Controls the whole systems by analyzing the

data , deriving the appropriate conclusion and determining the actions required .

DATA INSTRUCTIONS Transmits the decision and associated

instructions back to the member of the structure. ACTION DEVICE It takes the action by triggering the control

devices

Control systemControl system• monitors the sensor’s signalmonitors the sensor’s signal• processing the information in order to determine processing the information in order to determine

action required.action required.• If an action is required, then a signal is applied to the If an action is required, then a signal is applied to the

appropriate actuator.appropriate actuator.

SensorSensor• To monitor environmental changes To monitor environmental changes • and generate signals proportional to the changing and generate signals proportional to the changing

measured.measured.

ActuatorActuator• used to change the properties of the smart structure in used to change the properties of the smart structure in

order to achieve the desired responseorder to achieve the desired response

Sensors and ActuatorsSensors and Actuators

Mechanical Energy

Electrical Energy

Sensor Actuator

DisplacementVelocityAccelerationForcePressureTemperature

Current VoltageCapacitanceResistanceInductance

Sensors attached to columnsSensors attached to columns

Sensors attached to Deck slabsSensors attached to Deck slabs

Sensors attached to Deck slabsSensors attached to Deck slabs

Structural uses of SMA’sStructural uses of SMA’s

Active control of structures

Passive control of structures

Smart material tag

Retrofitting

Self healing

Structural health monitoring

Active control of structuresActive control of structures The structure adapts its dynamic characteristics

to meet the performance objectives at any instance

Test Setup of the Cantilevered Beam with SMA Wire Test Setup of the Cantilevered Beam with SMA Wire ActuatorActuator

Passive control of structuresPassive control of structures Special braces for framed structures

Isolation devices for buildings and bridges

Smart Material TagSmart Material Tag Used in composite structures

Can be monitored externally throughout the life of the structure

The internal material conditions like moisture, voids, cracks may be interpreted via sensing.

RetrofittingRetrofitting SMAs can be used as self stressing fibers and thus they can be

applied for retrofitting

Self-stressing fibers are the ones in which the reinforcement is placed into the composite in non stressed state

Prestressing force is introduced into the system by providing SMAs

Treatment can be applied at any time after hardening of the matrix instead of during its curing and hardening

Self-healing

The deformation beyond the first crack can be fully recovered and cracks can be fully closed.

Structural Health Monitoring

Use of piezo transducers, surface bonded to the structure or embedded in the walls of the structure can be used for structural health monitoring and local damage detection.

APPLICATION OF SMART MATERIALS

CARBON FIBER REINFORCED CONCRETE Its ability to conduct electricity and most

importantly, capacity to change its conductivity with mechanical stress makes a promising material for smart structure.

The high density coupled with choice of fibers ranging from stainless steel to carbon applied under high pressure gives the product with outstanding qualities.

SMART CONCRETE

A mere addition of 0.5% of specially treated carbon fibers enables the increase of electrical conductivity of concrete.

Addition of load reduces the conductivity of the concrete, on removing of load concrete regains its original conductivity.

Functions as a traffic sensing recorder when used as road pavement .

Used to lay smart highways to guide self steering cars which at present follow tracks of buried magnets.

Smart building materials remove Smart building materials remove pollutantspollutants

These are special construction materials and These are special construction materials and coatings containing titanium dioxide (TiO2) coatings containing titanium dioxide (TiO2)

They can “capture” organic and inorganic air They can “capture” organic and inorganic air pollutants after they have been exposed to pollutants after they have been exposed to ultra-violet and/or sun rays. ultra-violet and/or sun rays.

The degraded polluting substances can then be The degraded polluting substances can then be washed away by rainwater.washed away by rainwater.

Sensor Networking

Structure

Satellite

Telephone

RadioCellular

Fiber Optic

Communications

IP

Users

A Schematic view of a Smart BridgeA Schematic view of a Smart Bridge

Sensors atop flagpole measure movement, Dupont court

Sensor box mounted on flag pole

Rion Antirion Bridge, Greece

Rion Antirion Bridge, Greece

CONCLUSION

The technologies using smart materials are useful for both new

and existing constructions. Of the many emerging

technologies available the few described here need further

research to evolve the design guidelines of systems. Codes,

standards and practices are of crucial importance for the

further development.

With the benefits in sight , smart structures With the benefits in sight , smart structures technology is seeing quick moment into the civil technology is seeing quick moment into the civil engineering field. Civil infrastructures of the future engineering field. Civil infrastructures of the future will be integrated with sensors and control devices will be integrated with sensors and control devices through information networks to enhance their through information networks to enhance their performance at reduced life – cycle cost.performance at reduced life – cycle cost.

From an educational perspective it is desirable to From an educational perspective it is desirable to prepare the present and next generation of civil prepare the present and next generation of civil engineers for the advanced technologies which they engineers for the advanced technologies which they will use in the future.will use in the future.

ReferencesReferences Journal of professional issues in engineering education and practice ASCE / January 2008.Journal of professional issues in engineering education and practice ASCE / January 2008.

N.Krstulovic-Opara and A.E. Naaman, ACI Structural Journal, March – April 2000, pp 335-N.Krstulovic-Opara and A.E. Naaman, ACI Structural Journal, March – April 2000, pp 335-

344344

Web SitesWeb Sites

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