SMART MATERIALS FOR VIBRATION REDUCTION

1
Smart Materials For Vibration Reduction
A seminar Report Submitted by DIANA ALKEFLAWI
IN MECHANICAL ENGINEERING
AT
ERCIYES UNIVERSITY MECHANICAL ENGINEERING
DEPARTMENT KAYSERI 17/12/2015
2
Abstract
For active noise and vibration reduction tasks in
smart-structures technology piezoelectric
ceramics are first choice. They generate large
forces, have fast response time, are commercially
available as fibres, patches and stacks and allow
integration into structural components.
The purpose of this research is compare the
vibration test results for a plate with and
without smart damping. Also discusses the
benefits of smart materials when added to
existing damping materials in terms of vibration.
-i-
3
TABLE OF CONTENTS

• 
  
  Page
• CHAPTER 1 1 . INTRODUCTION
  ...... 1
• 1 What is Smart Materials ?......................
  ..................................................
  ......1
• 1.2 Traditional vs. Smart structure..
  2
• 3 Classification of Smart Materials..
  ..3
• 1.4 Smart Composites..7
• 5 Smart Structures.8
• 1.6 Importance For Smart Structures..
  .10
• 7 Smart System For Engineering
  Applications.........11
• 1.8 Smart Structure Applications
  ....12
• CHAPTER 2
• 2.1 What is vibration?................
  ..................................................
  ......................17
• 2.2 Terms Definitions..
  ..18
• 2.2.1 Shunt Circuit
  Design........18
• 2.2.2 Shunt
  Tuning....19
• 2.2.3 Damped vs. Undamped
  Vibration20
• 2.3 Vibration Benefits Of Smart
  Damping For Undamed Plates..22
• 2.4 Benefits Of Smart Damping For
  Damped Structures.....25
• 2.5 Summary ..
  .34

-ii-
4
CHAPTER ONE
1. Introduction to Smart Materials
1.1 WHAT IS SMART MATERIALS ?
-Smart or intelligent materials are materials
that have the intrinsic and extrinsic
capabilities, first, to respond to stimuli and
environmental changes, second, to activate their
functions according to these changes. Stimulus
stress, strain, light, electric field,
temperature , pressure,moisture, magnatic
field. Response motion or change in optical
properties,modulus, surface tension,
piezoelectricity etc.
5
1.2 Traditional vs . Smart structure
Traditional structures Designed for certain
performance requirements eg. load, speed ,life
span. Unable to modify its specifications if
there is a change of environment. Smart
Structures Can accommodate unpredictable
environments. Can meet exacting performance
requirement. Offer more efficient solutions
for a wide range of applications.
6
1.3 Classification of Smart Materials

• Actively Smart
• They possess the capacity to modify their
  geometric or material properties under the
  application of electric, thermal or magnetic
  fields, thereby acquiring an inherent capacity to
  transduce energy.
• Piezoelectric
• Magnetostrictive
• Shape memory alloys
• Electro-Rheological fluid, etc.
• They can be used as force transducers and
  actuators.

7

• Passively Smart
• Those smart materials that are not active
  are called passively smart materials. Although
  smart, they lack the inherent capability to
  transduce energy.
• Optic fibres
• These materials can act as sensors but not as
  actuators or transducers.

8
Fig Common smart materials and associated
stimulus response
5
9
Type of SMART Material Input Output
Piezoelectric Deformation Potential Difference
Electrostrictive Potential Difference Deformation
Magnetostrictive Magnetic Field Deformation
Thermoelectric Temperature Potential Difference
Shape Memory Alloys Temperature Deformation
Photochromic Radiation Color Change
Thermochromics Temperature Color Change
6
10
1.4 Smart Composites

• Combining two or more single smart materials to
  utilize the best properties of their individual
  constituents is the objective of any new smart
  composites.

11
1.5 Smart Structures
A smart structure is a system that incorporates
particular functions of sensing and actuation to
perform smart actions in an ingenious way. The
basic five components of a smart structure are
Data Acquisition (tactile sensing) the aim of
this component is to collect the required raw
data needed for an appropriate sensing and
monitoring of the structure. Data Transmission
(sensory nerves) the purpose of this part is to
forward the raw data to the local and/or central
command and control units.
Command and Control Unit (brain) the role of
this unit is to manage and control the whole
system by analyzing the data, reaching the
appropriate conclusion, and determining the
actions required. Data Instructions (motor
nerves) the function of this part is to transmit
the decisions and the associated instructions
back to the members of the structure. Action
Devices (muscles) the purpose of this part is to
take action by starting the controlling devices/
units.
8
12
9
13
1.6 Importance for Smart Structures
- Light weight - Warnings on problems that can
encounter - Preventative maintenance -
Performance optimization - Improved life cycle
10
14
1.7 SMART SYSTEM FOR ENGINEERING
APPLICATIONS
The scope of application of smart material
includes solving engineering problems for
creation of new products with unfeasible
efficiency and provides an opportunity that
generate revenue .
General Requirements and Expectations 1. High
degree of reliability, efficiency and
sustainability not only of the structure but
also of the whole system. 2. High security of the
infrastructures particularly when subjected to
extreme and unconventional conditions. 3. Full
integration of all the functions of the
system. 4. Continuous health and integrity
monitoring. 5. Damage detection and
self-recovery. 6. Intelligent operational
management system.
Smart Technologies Prospects 1. New sensing
materials and devices. 2. New actuation materials
and devices. 3. New control devices and
techniques. 4. Self-detection, self-diagnostic,
self-corrective and self-controlled functions of
smart materials/systems.
11
15
1.8 Smart Structure Applications

• 1- Aerospace
• - Damage detection
• -Vibration control
• -Shape control
• -Adaptive structures
• 2-Defence
• -Firing accuracy of weapons
• -Vibration and noise reduction in submarines
• -Smart missiles use smart fins which can warp to
  appropriate shapes

12
16

• 3-Automotive
• -Passenger comfort (noise control in cabin)
• -Vibration control (active engine mounts)
• -Health monitoring (smart sensors)
• 4-Industrial
• -Manufacturing (machine tool chatter control)
• -Air conditioning and ventilation (noise control)
  
• -Mining machinery (vibration control)

• 5-Medical
• Smart sensors
• Micro robotics
• Surgical tools
• 6-Civil
• Bridges
• Earthquake protection

17
Examples
-Vibration reduction in sporting goods a new
generation of tennis rackets, golf clubs,
baseball bats and ski boards have been introduced
to reduce the vibration in these sporting goods,
increasing the users comfort and reducing
injuries. -Smart clothes
14
18

• Noise reduction in vehicles filaments of
  piezoelectric ceramic fibres are used to counter
  noise in vehicles, neutralize shaking in
  helicopter rotor blades, or nullify or at least
  decrease vibrations in air conditioner fans and
  auto- mobile dashboards.

19
16
20
CHAPTER TWO
2.1 WHAT IS VIBRATION ?
Scientific Definition Any motion that repeats
itself after an internal of time.
Engineering Definition Deals with the
relationship between forces and oscillatory
motion of Mechanical systems.
A piezoelectric disk generates a voltage when
deformed (change in shape is greatly exaggerated
17
21
2.2 Terms Definitions
Shunt Circuit Design
Shunt Tuning
Damped vs. Undamped Vibration
2.2.1 Shunt Circuit Design
The smart damping technique chosen for this study
involved attaching piezoceramic devices that are
shunted with passive electrical circuits. When
the panel vibrates, as illustrated in Figure
below, the mechanical energy strains the
piezoelectric material and thereby generates
electrical energy .The shunted electrical
impedance then dissipates this electrical energy.
The components of these shunt circuits (resistors
,capacitors, and inductors) are chosen to produce
an effective mechanical impedance at desired
levels and frequencies.
I

• T- Stress by Plate on PZT Vi- PZT Voltage
• I - Circuit Current Rs- Shunt
  Resistance
• Ls- Shunt Inductance
  Zs-Equivalent Shunt
• 
  Impedance

Vi
Shunting of Piezoelectric Materials
18
22
2.2.2 Shunt Tuning
Tuning the PZT resonant shunt circuits The
first step is to determine the electrical
resonant frequencies required to dissipate the
mechanical energy. The second step is to
calculate the initial values for the variable
resistors in the shunt circuit. The final step
is to fine-tune the resistors with testing in
order to achieve optimal damping.
19
23
2.2.3 Damped vs. Undamped Vibration
Damped and undamped vibration refer to two
different types of vibrations. The main
difference between them is that undamped
vibration refer to vibrations where energy of the
vibrating object does not get dissipated to
surroundings over time, whereas damped vibration
refers to vibrations where the vibrating object
loses its energy to the surroundings.
20
24
Test Plate Configurations Used to Evaluate the
Benefits of Smart Damping
TEST PLATES
DAMPED TEST PLATE


DAMPED SHUNTED DAMPED SHUNTED DAMPED UNSHUNTED DAMPED UNSHUNTED
DAMPED
21
25
2.3 Vibration Benefits of Smart Damping for
Undamped Plates
Once the smart damping plate was constructed,
initial tests were performed on the shunted and
unshunted plates. The shunt circuits were tuned
to the resonant frequencies between 50 and 450 Hz
for the unshunted plate. Figure (1)
illustrates the effect of the tuned shunt
circuits on the plate vibration response. Peaks
3, 4, and 5 were the most significantly reduced
for the shunted plate.
22
26
Unshunted and Shunted Plate Vibration Response
2 10
Unshunted
Shunted
1 10
Plate Accel/Frame Accel, gs/gs
0 10
Fig (1)
-1 10
(HZ)
50 100 150 200
250 300 350 400
450
Effect of Adding Smart Material to an Undamped
Plate
Frequency Response Functions
2 10
Undamped
Unshunted
1 10
Plate Accel/Frame Accel, gs/gs
Fig (2)
0 10
-1 10
(HZ)
50 100 150 200
250 300 350 400
450
23
27
Table.1. Effect of Smart Damping on Peak
Vibrations
2
Peak Undamped (g/g) Shunted PZT (g/g) Reduction ()
1 (101 Hz) 57.79 31.84 56.1
3 (147 Hz) 47.74 7.53 84.6
4 (235 Hz) 11.28 4.05 64.1
5 (245 Hz) 47.97 3.87 91.9
The goal of the testing was to determine the
total vibration reduction achieved by the
application of smart damping. Table above
presents the decreases in the peak accelerations
that were obtained using the tuned shunts. The
results indicate that the smart damping
significantly reduced the four resonant peak
vibrations, with the largest reductions achieved
for peaks 3 and 5.
24
28
2.4 Benefits of Smart Damping for Damped
Structures
This section investigates the added benefits of
applying smart damping when used with
conventional passive damping materials. The
effect of adding smart damping materials to a
plate damped with unbacked carpet, shoddy
and unbacked carpet, and shoddy and 0.3 PSF
backed carpet
Fig(3)
Figure (3) Passive Treatments Used with Smart
Damping Materials
25
29
The evaluation was based on comparing the
vibration measurements with and without smart
damping for each of the above treatments. These
treatments, as shown in Figure (3) were cut
into 400 mm x 500 mm samples that were placed
over the test plates. Each material is evaluated
by measuring the plate vibrations similar to the
undamped cases. Shoddy is a foam pad made of
interwoven fabric scraps that is placed under the
carpeting in vehicles. The backed carpet has a
layer of rubber melted onto the carpet to add
damping with mass loading. The grade of carpet
is measured as pounds per square foot or PSF.
26
30
As was expected, the damping treatments altered
the frequency response of the plate which
required the shunts to be retuned for each
damping case. Once the shunt circuits were
optimized, the three different treatments were
tested for both the shunted plate and the
undamped plate. The augmenting vibration
benefits of PZTs are presented first followed by
the acoustic benefits.
27
31
Vibration Benefits of Adding Smart Damping to
Damped Structures
Another convenient method to assess the benefits
of smart damping materials is to evaluate their
broadband performance using a third-octave band
analysis. For the vibration data, 1/3-octave
values were determined for each center frequency.
It is evident in Figures below that the smart
damping has the most effect on accelerations
above 125 Hz. It is also noted that the PZTs add
less additional damping as the amount of
treatment increases and the vibrations decrease.
28
32
12
10
8
6
4
Decrease in Acceleration, (dB)
2
0
-2
-4
-6
-8
63
80
100
125
200
250
315
160
No Treatment
33
F r e q u e n cy, ( 1 /3 O c t ave B a n d s )
D e c r e a se in V i b ra tio n L e v e l s U
sin g S m a r t D a m p i n g
10
8
6
4
2
Decrease in Acceleration, (dB)
0
-2
-4
-6
Unbacked carpet
34
4
3
2
1
Decrease in Acceleration, (dB)
0
-1
-2
-3
-4
63
80
100
125
160
200
250
315
Shoddy Unbacked Carpet
35
F r e q u e n cy, 1 /3 O c t ave B a n d s
3
2
1
Decrease in Acceleration, (dB)
0
-1
-2
-3
-1
-4
Shoddy 0.3 PSF Carpet
36
63 80 100 125 160 200 250 315
UNDAMPED PLATE 0.5 -1 8 -6 10 3 10 12
UNBACKED PLATE -4 -1 -2 -6 5 1.8 5 8
SHODDY UNBACKED PLATE -2 -0.1 -3 0.1 1.2 1.6 1 4
SHODDY 0.3 PSF PLATE -1 1.5 -4 2 0.9 1 0.5 1

Hz
TYPES OF PLATES
37
2.5 Summary
The benefits of smart damping materials,
specifically piezoceramics with shunt circuits,
in reducing vibrations were addressed. Tests were
conducted on a test plate with shunted PZTs. A
comparison of the results with an undamped plate
showed that the smart damping materials can
significantly lower both the plate vibration for
both narrowband and broadband frequencies.
34
38
References

• An Experimental Evaluation of the Application of
  Smart Damping Materials for Reducing Structural
  Noise and Vibrations Kristina M. Jeric

• Smart materials for active noise and vibration
  reduction
• H. P. Monner German Aerospace Center (DLR),
  Institute of Composite Structures and Adaptive
  Systems Lilienthalplatz 7, D-38108 Brunswick,
  Germany

• INTRODUCTION, CLASSIFICATION AND APPLICATIONS OF
  SMART MATERIALS AN OVERVIEW American
  Journal of Applied Sciences 10 (8) 876-880, 2013
  Susmita Kamila

• Overview of Smart Materials Bishakh
  Bhattacharya Nachiketa Tiwari
• Department of Mechanical Engineering
  Indian Institute of Technology, Kanpur

• SMART MATERIALS AND SMART SYSTEMS FOR THE FUTURE
  by Georges Akhras Canadian Military Journal
  Autumn 2000

• Ref. H.W. Hagood, and A von Flotow, Damping of
  Structural Vibrations with Piezoelectric
  Materials and Passive Electrical Networks,
  Journal of Sound and Vibration

• Akhras, G., Advanced Composites for Smart
  Structures, Proceedings, ICCM-12, 12th
  International Conference on Composite Materials,
  Paris5-9.

• International Journal of Mechanical and
  Industrial Engineering (IJMIE) ISSN No.
  2231-6477, Vol-3, Iss-1, 2013

35
39
THANK YOU FOR YOUR LISTENING
36

• IF THERE is any
• QUESTION
• YOU WELCOME