Vibration Damping Via Acoustic Treatment Attached To Vehicle Body Panels

129 Pages·2015·5.28 MB·English

University of Windsor
Scholarship at UWindsor
Electronic Theses and Dissertations
2015
Vibration Damping Via Acoustic Treatment
Attached To Vehicle Body Panels
Carlo Gambino
University of Windsor
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Gambino, Carlo, "Vibration Damping Via Acoustic Treatment Attached To Vehicle Body Panels" (2015).Electronic Theses and
Dissertations.Paper 5268.
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Vibration Damping Via Acoustic Treatment Attached To Vehicle Body Panels

By
Carlo Gambino

A Thesis
Submitted to the Faculty of Graduate Studies
Through Mechanical, Automotive & Materials Engineering
in Partial Fulfillment of the Requirements for
the Degree of Master of Applied Science
at the University of Windsor

Windsor, Ontario, Canada
2015

© 2015 Carlo Gambino
Vibration Damping Via Acoustic Treatment Attached To Vehicle Body Panels
by
Carlo Gambino

APPROVED BY:
______________________________________________
Dr. N. Kar
Department of Electrical & Computing Engineering

______________________________________________
Dr. R. Gaspar
Department of Mechanical, Automotive & Materials Engineering

______________________________________________
Dr. C. Novak, Advisor
Department of Mechanical, Automotive & Materials Engineering

January 20th, 2015
DECLARATION OF ORIGINALITY

I hereby certify that I am the sole author of this thesis and that no part of this thesis has
been published or submitted for publication.
I certify that, to the best of my knowledge, my thesis does not infringe upon anyone‟s
copyright nor violate any proprietary rights and that any ideas, techniques, quotations, or any other
material from the work of other people included in my thesis, published or otherwise, are fully
acknowledged in accordance with the standard referencing practices. Furthermore, to the extent
that I have included copyrighted material that surpasses the bounds of fair dealing within the
meaning of the Canada Copyright Act, I certify that I have obtained written permission from the
copyright owner(s) to include such material(s) in my thesis and have included copies of such
copyright clearances to my appendix.
I declare that this is a true copy of my thesis, including any final revisions, as approved by
my thesis committee and the Graduate Studies office, and that this thesis has not been submitted
for a higher degree to any other University or Institution.

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ABSTRACT
Currently, in the automotive industry, the control of noise and vibration is
the subject of much research, oriented towards the creation of innovative solutions
to improve the comfort of the vehicle and to reduce its cost and weight. This thesis
fits into this particular framework, as it aims to investigate the possibility of
integrating the functions of sound absorption\insulation and vibration damping in a
unique component.
At present the bituminous viscoelastic treatments, which are bonded to the
car body panels, take charge of the vibration damping, while the sound absorption
and insulation is obtained by means of the poroacoustic treatments. The solution
proposed here consists of employing porous materials to perform both these
functions, thus allowing the partial or complete removal of the viscoelastic
damping treatments from the car body. This should decrease the weight of the
vehicle, reducing fuel consumption and emissions, and it might also benefit
production costs.

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ACKNOWLEDGEMENTS
I would like to express the deepest appreciation to FIAT, Chrysler, Politecnico di
Torino, and University of Windsor, for giving me the opportunity to take part to the Joint
Master Degree program and to work on this thesis.
My gratitude goes to all the people who have collaborated on this project, in
particular, Marco Danti and Daniele Stanga, for their constant support, Dilal Rhazi, for his
valuable suggestions, and to my academic tutors Colin Novak and Marco Carlo Masoero
for their wise advice.

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TABLE OF CONTENTS

DECLARATION OF ORIGINALITY .............................................................................. iii
ABSTRACT ....................................................................................................................... iv
ACKNOWLEDGEMENTS .................................................................................................v
LIST OF TABLES ............................................................................................................. ix
LIST OF FIGURES .............................................................................................................x
LIST OF ABBREVIATIONS ............................................................................................xv
NOMENCLATURE ........................................................................................................ xvi
CHAPTER 1 INTRODUCTION .........................................................................................1
1.1 Introduction ....................................................................................................................... 1
1.2 Motivations ......................................................................................................................... 2
1.3 Objectives ........................................................................................................................... 3
1.4 Methodologies .................................................................................................................... 4
1.5 Thesis Organization ......................................................................................................... 5
CHAPTER 2 REVIEW OF LITERATURE ........................................................................6
2.1 Noise and vibration in vehicles ..................................................................................... 6
2.2 Vibration damping treatments ................................................................................... 11
2.3 Poroacoustic treatments ............................................................................................... 12
2.3.1 Different categories of poroacoustic treatments and their properties ...................... 14
2.3.2 Vibroacoustic behaviour of porous materials............................................................ 21
2.4 Finite element vibroacoustic analysis of panels treated with poroacoustic
materials .................................................................................................................................. 27
2.4.1 Modal analysis ............................................................................................................ 28
2.4.2 Finite element vibroacoustic analysis of systems composed by structural components
and poroacoustic materials ................................................................................................... 33
2.5 Summary and final remarks on the review of literature ....................................... 43
CHAPTER 3 METHODOLOGIES AND RESULTS ......................................................45
3.1 Experimental tests ......................................................................................................... 45
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3.1.1 Experimental setup...................................................................................................... 45
3.1.2 Tests carried out on the steel plate ............................................................................. 47
3.1.3 Experimental results ................................................................................................... 49
3.2 Introduction to the FEA software ................................................................................ 52
3.2.1 Modal frequency response step 1: Normal modes extraction ................................... 54
3.2.2 Modal frequency response step 2: Reduced impedance matrixes of the porous trim55
3.2.3 Modal frequency response step 3: Structure-acoustic cavity coupling .................... 57
3.2.4 Modal frequency response step 4: Projection of the reduced impedance matrix ..... 59
3.2.5 Modal frequency response step 5: Modal frequency response solver....................... 59
3.3 Numerical modeling ...................................................................................................... 60
3.3.1 Mesh of the elastic component ................................................................................... 60
3.3.2 Mesh of the porous trim ............................................................................................. 61
3.3.3 Presence of an acoustic cavity ................................................................................... 63
3.3.4 Sampling frequencies for the calculation of the reduced impedance matrices ....... 64
3.4 Validation of the numerical model............................................................................. 67
3.4.1 Frequency response of the bare plate ........................................................................ 67
3.4.2 Effect of the porous treatments on the frequency response of the plate .................. 70
3.5 Sensitivity analysis on porous material properties ................................................ 75
3.5.1 Methodology ............................................................................................................... 75
3.5.2 Relationship between the porous material properties and the response of the system
77
3.5.3 Negligible parameters ................................................................................................ 83
3.6 Vibration damping performances of poroacoustic treatments ........................... 83
3.6.1 Performance index ..................................................................................................... 83
3.6.2 Comparison between different materials ................................................................... 84
3.7 Use of the poroacoustic treatments on a vehicle for damping the vibration of
the floor .................................................................................................................................... 87
3.7.1 Comparison among different layouts of the treatments ............................................ 88
CHAPTER 4 CONCLUSIONS AND RECOMMENDATIONS .....................................96
4.1 Introductory comments ................................................................................................ 96
4.2 Conclusions ...................................................................................................................... 97
4.3 Recommendations .......................................................................................................... 99
vii
REFERENCES/BIBLIOGRAPHY..................................................................................102
VITA AUCTORIS ...........................................................................................................107

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LIST OF TABLES
Table 2.1: Average fiber diameter and density of various fibrous acoustic materials [4] . ............. 16
Table 2.2: Density of various fibrous materials used for noise control [4] ...................................... 18
Table 2.3: Principal properties of the poroelastic materials. ............................................................ 18
Table 2.4: Nomenclature of the principal FRF used in modal analysis. .......................................... 32
Table 3.1: Characteristics of the felts employed for the validation of the numerical model,
provided by the supplier of the treatments. ...................................................................................... 47
Table 3.2: Optimized frequency set for the calculation of the impedance matrices. ....................... 67
Table 3.3: Material properties database, with the maximum and minimum values underlined for
each variable. ................................................................................................................................... 76
Table 3.4: Nominal values and range of variation for the porous material properties. .................... 77
Table 3.5: Material properties of the optimized treatment. .............................................................. 85

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