This document provides an overview of computational models for smart structures. It discusses how smart structures can adapt to environmental changes using sensors and actuators. A smart structure uses piezoelectric materials as sensors and actuators and includes a processor to control the structure's response based on sensor signals. Finite element modeling is used to simulate the behavior of smart structures under different disturbances. Both simulations and experiments are conducted on active vibration control of smart plates to reduce vibrations. Smart structures have applications in areas like structural health monitoring and active noise/vibration control.

1. Computational Model for Realization
of
Smart Structure
Dr. Vivek Gupta
Assistant Professor
Department of Physics
GJUST, Hisar
Ph. 94181-24480
Email: vivekgupta.skgt@gmail.com

2. Smart Structures
Future Structures
 Also known as intelligent / adaptive / active structures
 Structures whose structural characteristics can be changed in order
to adapt to environmental changes or to meet mission requirements
 Many industrial applications :
• Structural health monitoring
• Shape control, precision positioning etc.
• Active noise control
• Active vibration control
 Interdisciplinary in nature.

3. Smart Structure
Schematic Diagram
 Inherent sensing & control capabilities
 Needs a processor to manipulate sensor signals
 Uses external source of energy to control the response
Base Structure
Sensor
Actuator
Processor
Amplifier
Power Supply

5. Sensors & Actuators
in a smart structure
 Strain gauges
 Magneto rheological fluid dampers
 Electro rheological fluid dampers
 Shape memory alloys
 Piezoelectric materials
 Bio-sensors etc.

6. Piezoelectric Sensors and Actuators
Mostly used in a Smart Structure
 Generate electric signal when
subjected to mechanical strains and
vice versa i.e. they exhibit direct &
inverse piezoelectric effects
 Can act as both sensors and
actuators
 Have fast response, easy fabrication,
design flexibility, low wait, low cost,
large operating band width, low
power consumption etc.
Z
X, P
Y
V
Z, P
V
X
Y
Extension-bending mode
Shear mode

7. Bio-sensors

8. Smart Bridge

9. Smart Piezo Structure
 Electromechanical Interaction between the base structure and
Piezoelectric Sensors/Actuators is captured by constitutive equations:
Direct Piezoelectric Effect or Sensor equation:
Inverse Piezoelectric Effect or Actuator Equation:
 Their performance depends upon
• Accuracy of the mathematical model
• Accuracy of the sensor signal
• Application of correct control voltages on actuator by control law
• Application of desired forces by the actuator
       D e E  
        T
c e E  

10.  Vibrations are part of machines due to presence of moving parts.
 Vibrations cause noise pollution, damage to machines and the structure.
 Results in recurring financial losses, decreases life of structures.
 Vibration control is necessary to increase the life and performance of a
structure
 Active Vibration Control is the most explored application of smart
structure
• Uses external source of energy to control vibrations
• Attenuates low frequency vibrations
• No change in overall size & mass of the structure
Active Vibration Control
Most explored application of smart structure

11. Smart structure is mathematically modeled.
Response of smart structure to different type of disturbances is observed
doing simulations in suitable software e.g. MATLAB.
A suitable control law is designed to control the desired vibration modes.
Simulations results are analyzed and practical viability is assessed.
Experiments on AVC of smart structure are performed.
Active Vibration Control
State of the art
----- Uncontrolled
----- Controlled

12. Finite Element Technique
Side view of ‘finite element’
Piezo
Piezo
Base Structure
Top view of the ‘finite
element’
Smart piezo structure divided into
finite elements
1 18 19 36 37 54 55 72 73
9 10 27 28 45 46 63 64 81
Node
Piezo
Sensor /
Actuator

13. Finite Element Model
For one finite element
Define element shape, no. of nodes, dof, displacement along z-direction and strains
 Kinetic Energy
 Potential Energy
 Electric Energy stored
 Energy stored due to external force
 Work required to apply external charge
 Lagrangian
 Hamilton’s Principle
2 21 1
2 2
e s P
S P
T w d w d     & &
       
1 1
2 2
T T
e
S P
V d d       
   
1
2
T
elect
P
W E D d 
   ( )
T e
ext I S S
AS
W w f dA 
( )ext II P
AP
W qvdA  
( ) ( )
( )e e elect ext I ext II
L T V W W W    
2
1
0
t
t
Ldt 

14. Vibrations of Smart Plate
Simulation results
First vibration mode Second vibration mode
Third vibration mode Overall vibration behaviour

15. Making a smart piezo structure
Sensor–Actuator Pair
Cantilevered plate bonded with one
collocated sensor-actuator pair
Piezo-sensor bonded to a plate

16. AVC of a Smart Plate at Elevated Temperatures
Experimental Set-up
CPU
Monitor
RT Engine
(with A/D & D/A DAQ Card)
Connector Box
Sensor-Actuator Signal
Conditioner
Thermal Chamber
 Amplified sensor signal is fed into ‘PXI Based RT System’
 Control algorithm program written in ‘Lab VIEW 7.1 RT’ is
downloaded into RT Engine
 Amplified control signal is applied on the actuator.

17. AVC of a Smart Plate
Experimental Results

18. Piezoelectric Vibration Energy Harvesting

19. Smart City

20. THANKYOU !