DEPARTMENT OF ME
SCIENTIFIC ACHIEVEMENTS THAT
THE WORLD HAS MADE SINCE THE
BEGINNING OF HUMAN CIVILIZATION
• Up to 1760-:Very little scientific activity
• 1769 -:James watt invented steam engine.
• 1800-1900-:Age of industrialization
• 1900-2000-:Age of information
• After 2000-: Age of decision
SMART MATERIALS-WHY THIS NAME?
2. Showing mental alertness and
1. To perceive ones environment
2. To know/comprehend and learn
3. To understand
4. To foresee problems
5. To think abstractly.
DESIRABLE ATTRIBUTES OF A
• Integration of functions( Sensor , Actuator and
A system which has intrinsic
sensor, actuator and control
mechanisms whereby it is capable
of sensing a stimulus, responding
it and reverting to its original state
after the stimulus is removed
• Material which has the intrinsic or extrinsic
capabilities to respond to an external stimulus
in a functionally useful manner.
• E.g. : Zinc oxide varistors (ZNO)
• Also called functional materials
• A material can be considered smart when a
input stimulus of a variable changes the
output of other variables not given as input
A material is smart if a specific response is
produced to a combination of inputs.
MAIN ADVANTAGES RESPECT
TO TRADITIONAL COMPONENTS
a) act simultaneously as sensors and
b) Perform controlled mechanical action
without any external mechanisms
c) Are adaptive with the environmental
d) High level of miniaturization
e) New functions development
• SMART STRUCTURE
A smart structures integrates the properties
of embedded sensors, actuators and control
mechanisms in order to respond to a given
stimulus in a functionally useful manner.
hardware and or software control
Need for smart systems
i. Optimizing response of large complex
ii. Perform enhancements otherwise not
SCHEMATIC OF A SMART STRUCTURE
IDEAL SMART STRUCTURE
Distributed and integrated
Sense temperature, humidity stress,force,pressure etc
Distributed and integrated
Generate shape, force and motion
Change stiffness and damping level.
Local level decision/actuation
High level communication with brain
COMPARISON WITH BIOLOGICAL
Useful strength to weight ratio
Self repairing systems
Adaptive joining mechanisms(mainly muscles and tendons)
Processing is distributed with central monitoring
• Communication channels throughout the systems(neurons)
• Central processor is highly adaptive and self configures in the
light of experience
• Energy transfer mechanisms involve chemically burned
SMART SYSTEMS RESEARCH
• Smart systems is a multidisciplinary area
requiring understanding of
SMART MATERIAL RESEARCHUNDERSTANDING OF DIFFERENT DOMAINS
Mechanics and structurures
Control and processing
Dynamics and vibrations.
Materials and systems.
Computer hardware and software.
Manufacturing and quality control.
SMART SYSTEMS EXPERTISE
WHAT CONSTITUTES A SMART SYSTEM
• Mechanical structures
• Signal processing and data reduction
Components of smart system
To monitor environment changes and generate signals proportional to the
The actuators are used to change the properties of the smart structure in
order to achieve the desired response
The control system continuously monitors the sensors signal, processing
the information in order to determine if action is required ,if an action is
required then a signal is applied to the appropriate actuators.
SMART STRUCTURES CLASSIFICATION
• PASSIVELY SMART (eg:fibre optic sensor)
• Structures have the ability to respond to a stimulus in a
useful manner without assistance of electronic controls
or feedback systems.
• Structures utilize feedback loops which accelerate the
recognition and response process.
VERY SMART(OR INTELLIGENT).
• Structures utilize the nonlinear property of the
sensor,actuator,memory and or feedback systems to
tune the response behavior
• A number of different actuators can be
incorporated into a smart structure in order to
generate the appropriate response to a
detected environmental variation. This type of
actuator is dependent on a number of
NATURE OF ACTUATION
• chemical etc.
NATURE OF DRIVING AGENCY
• Thermal,magnetic,electrical,chemical etc
• Corrosion,thermal,magnetic,electrical etc
Size,geometry,mechanical properties etc.
PROPERTIES OF THE ACTUATOR
• A number of different sensors can be
incorporated into a smart structure to
measure a number of different environmental
variations.the type of sensor utilized in smart
structures is dependent on a number of
• Size,geometry,mechanical properties
• OPERATIONAL PROPERTIES
• Sensitivity,bandwidth,linearity,gauge length,
operational range etc.
Smart control system
• The smart control system will provide
feedback control for the sensors and
• The scs will include the interfaces necessary
for the operation of the subsystem modules.
SMART CONTROL SYSTEM
THE SCS WILL CONSIST OF THE FOLLOWING
• Analogue to digital and digital to analogue
• Input signal amplification and filtering.
• Control algorithm.
• Digital signal processing(DSP)
• Output power supply.
APPLICATION OF SMART SYSTEMS
• It possesses the property of converting
mechanical energy into electrical energy and
• Mechanical stress
Potential field : SENSOR(DIRECT EFFECT)
• Electric field
• When mechanical stresses are applied on the
• If those charges are collected on a conductor
that is connected to a circuit, current is
• When electric potential (voltage) is applied to
the surface of the piezoelectric material,
mechanical strain is generated (ACTUATOR)
• If the piezoelectric material is bonded to a
surface of a structure, it forces the structure
to move with it.
FORMS OF PIEZO MATERIALS
• 1-3 piezocomposites
• Active fiber composites
2. PZT(actuator material)
3. PVDF(sensing material)
FIBER OPTIC SENSORS
• Works on the principle of total internal reflection.
• All light energy will be completely reflected.
• It essentially sensor material. It cannot do any
• When the system in which these fibers are
embedded undergoes any change, then the
incident wave length of the light undergoes a
physical shift, which indicates the change the
COMPONENTS OF FIBER OPTIC SENSOR
a) Source of light
b) Length of sensing fiber
c) Photo detector
e) Processing and display optics
TYPES OF FIBER OPTIC TYPES
BASED ON MODULATION OR DEMODULATION
• Phase sensor
• Frequency sensor
• Polarization sensor
BASED ON APPLICATION OF FOS
• Physical sensor
• Chemical sensor
• Biomedical sensor
MODE OF SENSING
• Extrinsic sensor
• Intrinsic sensor
• Principle materials-LEAD MANGANESE
• LEAD LANTHANUM ZIRCONATE TITANATE(PLZT)
• This is used for actuation purpose only.
• Suitable for frequencies up to 50khz
• E=700GPA and very brittle
• Fast response time.
• Low hysteresis loop and hence low loss material.
• Eg:TERFENOL-D (alloy of Terbium, iron(FE))
• Phenomenon similar to electrostriction
• Can be used for both sensing and actuation
• Rarest of the rare earth material. and hence very expensive
• Large strain levels(2%)
• E=200gpa and length of 200mm.
• Narrow hysteresis loop and hence low loss
• Generates large actuating force(order of kilonewtons)
SHAPE MEMORY ALLOY (SMA)
• Change mechanical properties with the
change of temperature
• Regain its original shape when heated
• Normal temperature-one phase
• Temp increases-changes its phase and retains
• Main disadvantage is slower response time
SHAPE MEMORY ALLOYS(SMA)
made by nixing nickel and titanium
T<TC, Martensitic phase-plastic state-large strains can be
applied with little stress.
T>TC, Austenitic phase-memory phase-retains its original
Actuation is caused by transforming the material from
martensite to austenitic phase. This process causes enormous
amount of stress, which can be used for actuation purpose.
Slow reaction time
Properties depend on the composition, the phase and past
• Viscous properties are modified by applying electric fields
• Obtained by mixing SILICONE OIL AND CORN STARCH.
• In the neutral state particles are uniformly distributed.
Under electric field the large dielectric constants
redistributes the particles changing the viscous properties.
• E R fluid are non Newtonian fluids.
• Useful in transforming shear stresses
CHANGES LIQUID TO
SOLID TO LIQUID
MAGNETO RHEOLOGICAL FLUIDS
• LITHIUM GREASE MIXED WITH MICRON SIZED IRON
• Externally applied magnetic field in a direction normal to
the fluid flow direction from dipoles in the iron particles.
• Magnetic poles start attracting each others to the
direction of the field hence forming chains.
• The chains then form a skeleton within the fluid, which
gains the fluid controllable yield stress.
CHANGES TO LIQUID
SOLID TO LIQUID
This property can be used in changing the damping characteristics
of a damper