PSZ 19:16 (Pind. 1/97)
Universiti Teknologi Malaysia
BORANG PENGESAHAN STATUS TESIS*
JUDUL: PREDICTION OF NOISE RADIATION ON CYLINDER HEAD
SESI PENGAJIAN: 2004/2005
Saya MUHAMAD KHAIRUDIN BIN A WANG
(HURUF BESAR)
mengakll membenarkan tesis (PSMISarjanalDekterFalsafah)* ini disimpan di Perpustakaan Universiti Teknologi Malaysia dengan syarat-syarat kegunaan seperti berikut:
1. Tesis adalah hakmilik Universiti Teknologi Malaysia. 2. Perpustakaan Universiti Teknologi Malaysia dibenarkan membuat salinan untuk tujuan pengajian
sahaja. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi
pengajian tinggi. 4. **Sila tandakan (..J)
D D
SULIT
TERHAD
(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKT A RAHSIA RASMI 1972)
(Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan)
~ TIDAK TERHAD
~~o _. (TANDATANGAN PENULIS)
Alamat Tetap:
DEPAN SEKOLAH KG. BHARU SERADA,
20050 KUALA TERENGGANU,
TERENGGANU DARUL IMAN.
Tarikh: _...::.0;::...8..=..:N,-,=,O:.....:VE...=:=.;MB=E"",R.:;.;2::..:0:..:;:0....:..4_
CATATAN: Polong yang lidak bcrkcnaan
Disahkan oleh
(T ANDAT ANGAN PENYELIA)
PM. DR. ROSLAN ABDUL RAHMAN
Nama Penyelia
Tarikh: 08 NOVEMBER 2004
•• Jikn Icsis ini SUUT alau TERHAD, sila lampirkan sural daripada pihak bcrkuasa/organisasi bcrkcnaan dengan menyalakan sekali scbab dan lempoh lesis pcrlu dikelaskan sebagai SUUT alau TERHAD. Tesis dimaksudkan sebagai lesis bagi Ijazah Doklor Falsafah dan Smjana secara pcnyclidikan, atau discrtasi bagi pcngajian sccara keIja l,:ursus dan pcnyclidikan, atau Laporan Projek SaIjana Muda (pSM).
"I declare that I have read this thesis and in my opinion, it is sufficient in term of
scope and quality for the award of the degree of
Signature
Supervisor
Date
Master of Engineering (Mechanical)"
ASSOC. PROF. DR. ROSLAN ABDUL RAHMAN
08 NOVEMBER 2004
Fakulti Kejuruteraan Mekanikal
Universiti Teknologi Malaysia
PENGESAHAN PENYEDIAAN SALINAN E-THESIS
Judul Tcsis : PREDICTION OF NOISE RADIATION ON CYLINDER HEAD
Ijazah Sarjana
Fakulti Kejuruteraan Mekanikal
Scsi Pcngajian 2004/2005
Saya MUHAMAD KHAIRUDIN BIN A W ANG (HURUF BESAR)
U1M(FKM)-I/02
No Kad Pengenalan 760323 - 11 - 5577 mengaku telah menyediakan salinan e-thesis
sarna seperti tesis asal yang telah diluluskan oleh panel pemeriksa dan mengiJ..:ut panduan penyediaan
Tesis dan Disertasi EleJ...-tronik (TDE), Sekolah Pengajian Siswazah, Universiti Teknologi Malaysia,
November 2002.
(Tandatangan pelajar)
Alamat tetap:
Depan Sekolah Kg. Bharu Serada,
20050 Kuala Terengganu,
Terengganu.
Tarikh: 08 NOVEMBER 2004
(Tandatangan penyelia sebagai saksi)
Nama pcnycJia:
PM. DR. ROSLAN ABDUL RAHMAN
Fakulti: Kejuruteraan Mekanikal
Tarikh: 08 NOVEMBER 2004
Nota: Borang ini yang tclah dilcngkapi hcndaklah dikcmukakan kcpada FKM bersama penycrahan CD.
PREDICTION OF NOISE RADIATION ON CYLINDER HEAD
MUHAMAD KHAIRUDIN BIN A WANG
A project report is submitted to the Faculty of Mechanical Engineering in partial
fulfilment of the requirements for the award of the degree
Master of Engineering (Mechanical)
Faculty of Mechanical Engineering
Universiti Teknologi Malaysia
NOVEMBER 2004
I hereby declared that this thesis entitled, "Prediction Of Noise
Radiation On Cylinder Head", is the result of my
own work except the tenns, table and figures
Signature
Name
Date
that I have state the source.
L~~ -- . MUHAMAD KHAIRUDIN BIN A WANG
08 NOVEMBER 2004
11
To my beloved mother andfather,
Y01ll1lade evelJ'thing worthwhile.
iii
ACKNOWLEDGMENT
First of all, I am greatly indebted to ALLAH SWT on His blessing to make
this project successful.
IV
I would like to take this opportunity to express my highest thankfulness and
appreciation to PM Dr. Roslan Abdul Rahman and research officers for their patience
and guidance.
As well, I would like to express my appreciation to my family for never
ending support and my dearest friends, Muhammad Saufi, Babul Salam and others
that have always assist me when I faced problems. Without the mentioned parties, it
would be impossible for me to complete this thesis accordingly and successfully.
THANK YOu.
v
ABSTRACT
Noise radiation analysis of an engine's component can be implemented
through several methods such as theoretical calculations, experimental and
simulation. The use of finite element method integrated with boundary element
method based computer software in engineering field has shown growing interest due
to shorter duration of analysis and easy to use. In this analysis, observation of
vibration characteristic for two-stroke engine's cylinder head is carried out. Initially,
finite elements are used to create the engine's cylinder head model. Data gained
from modal analysis is used for prediction of noise radiation from cylinder head
surfaces. At this stage, acoustic boundary element model is preferred instead of
finite element model. Finally, the results of this study can be used for further
analysis in designing of two-stroke gasoline engine.
V\
ABSTRAK
Kajian kebisingan bagi sesuatu komponen enjin boleh dilakukan dengan
pelbagai kaedah seperti pengiraan secara teori, secara eskperimen dan juga simulasi.
Penggunaan kaedah unsur sempadan disepadukan dengan peri sian komputer
berasaskan kaedah unsur terhingga sedang berkembang pesat dalam bidang
kejuruteraan kerana ia menjimatkan masa dan mudah digunakan. Oleh itu, kajian ini
memanfaatkan penggunaan perisian komputer untuk menyelesaikan masalah.
Pemerhatian terhadap ciri-ciri getaran bagi model kepala silinder enjin dua-lejang
dilakukan. Pada mulanya, unsur-unsur terhingga akan digunakan untuk membentuk
model kepala silinder enjin. Data-data yang diperolehi dari analisis normal mode
akan digunakan bagi meramal kebisingan yang terpancar dari permukaan kepala
silinder. Pada peringkat ini, model akustik unsur sempadan lebih sesuai digunakan
berbanding model unsur terhingga. Akhirnya, kajian yang dijalankan ini baleh
dimanfaatkan dalam merekabentuk kampanen enjin yang mengeluarkan bunyi yang
rendah pada masa akan datang.
Vll
TABLE OF CONTENTS
CHAPTER TITLE PAGE
TITLE PAGE
DECLARA TION II
DEDICATION iii
ACNOWLEDGEMENT IV
ABSTRACT V
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xi
LIST OF FIGURES xii
LIST OF SYMBOLS xiv
LIST OF APPENDIXES xv
CHAPTER I INTRODUCTION 1
1.1 Background Studies
1.2 Objectives of Project 2
1.3 Scope 3
CHAPTERTI
2.1
2.2
2.3
2.4
2.5
CIIAPTERll
3.1
3.2
3.3
3.4
3.5
INTRODUCTION TO BOUNDARY
ELEMENT METHOD
Boundary Element Method
Governing Formulations ofBEM in Acoustic
Introduction to Finite Element Method
Advantages of Finite Element Method
Acoustic Transfer Vector
LITERATURE REVIEW
Literature Review
Two-stroke Engine
3.2.1 Basic Components Of A Two-stroke Engine
3.2.2 Operation Of Two-Stroke Engines
3.2.3 Advantages Of Two-Stroke Engines
Internal Combustion Engine Noise
3.3.1 Classification by Noise Characteristics
3.3.2 Classification by Engine Noise Source
Noise Generation in Internal Combustion Engine
Engine Surface Noise
\'111
4
5
7
9
10
13
13
17
17
19
20
20
21
21
22
23
CHAPTER IV
CHAPTER"
4.1
4.2
4.3
5.1
5.2
5.3
5.4
5.5
5.6
5.7
CHAPTER VI
6.1
6.2
DYNAMIC ANALYSIS
Dynamic Analysis Process
Nomlal Modes Analysis
24
24
26
4.2.1 Equations ofNomlal Modes Analysis 27
Frequency Response Analysis 29
4.3.1 Modal Frequency Response Analysis 32
METHODOLOGY
Noise Prediction Simulation
Geometries
Materials and Properties
Boundary Conditions
Finite Elements
Finite Element Meshing Process
Boundary Element Meshing Process
RESULTS AND DISCUSSIONS
Result ofNomlal Mode Analysis
Result of Noise Radiation
33
33
35
36
37
38
40
41
44
44
49
IX
CHAPTER VII SUGGESTIONS AND CONCLUSION
7.1 Suggestions
7.2 Conclusion
REFERENCES
APPENDIXES
56
56
57
58
60 - 109
x
Xl
LIST OF TABLES
TABLE NO. TITLE PAGE
3.1 Natural frequencies of original model and modified model 15
6.1 Comparison of natural frequencies 45
6.2 Types of vibration and brief description of mode shapes 48
6.3 Reduction of SPL before and after modification
at 1500 rpm 53
6.4 Reduction of SPL before and after modification
at 2000 rpm 54
6.5 Reduction of SPL before and after modification
at 2500 rpm 54
6.6 Maximum normal velocities at 1500 rpm 55
6.7 Maximum normal velocities at 2000 rpm 55
6.8 Maximum normal velocities at 2500 rpm 55
XII
LIST OF FIGURES
FIGURE NO. TITLE PAGE
3.1 The locations on the engine where noise and vibration
signals were recorded 15
3.2 Analytical hannonic responses of original cylinder head
(location HI) 16
3.3 Analytical hannonic responses of modified cylinder head
(location HI) 16
3.4 Basic components of a two-stroke engine 18
4.1 Overview of dynamic analysis process 25
4.2 Pressure in combustion chamber at 1500 rpm 30
4.3 Pressure in combustion chamber at 2000 rpm 30
4.4 Pressure in combustion chamber at 2500 rpm 30
4.5 Comparison of pressure in combustion chamber
at three different speeds 31
5.1 Noise Prediction Methodology 34
5.2 Solid type of original cylinder head 35
5.3 Solid type of modified cylinder head 36
5.4 Constraints imposed on cylinder head 38
5.5 The standard tetrahedral element with ten nodes 39
5.6 FE model of original cylinder head 39
5.7 FE model of modified cylinder head 40
5.8 Acoustic meshing process 42
5.9 Acoustic BE model of cylinder head 43
Xlll
6.1 Mode shape and its natural frequency 47
6.2 Radiated sound power at 1500 rpm 49
6.3(a) Normal velocity mapping at 258 I Hz on BE model of
original cylinder head operating at 1500 rpm. 50
6.3(b) Normal velocity mapping at 2581 Hz on BE model of
modified cylinder head operating at 1500 rpm. 50
6.4 Radiated sound power at 2000 rpm 51
6.5 Radiated sound power at 2500 rpm 52
6.6(a) Normal velocity mapping at 2826 Hz on BE model of
original cylinder head operating at 2500 rpm. 52
6.6(b) Normal velocity mapping at 2826 Hz on BE model of
modified cylinder head operating at 2500 rpm. 53
XIV
LIST OF SYMBOLS
[K] Stiffness matrix represents elastic properties of the model
[M] Mass matrix represents inertial properties of the model
{ ii } Acceleration matrix
{ u} Displacement matrix
0) Natural frequency
t Time
Ai Eigenvalues (the natural or characteristic frequency)
f Natural frequency
E Modulus Young
U Poisson's ratio
p Mass density
m Mass per unit length
~11 Constant of the general solution
I Moment of inertia
Uj Displacement
8/ Angular displacement
Vi Acceleration
iJi
Angular acceleration
APPENDIX
APPENDIX A
APPENDIXB
LIST OF APPENDIXES
TITLE
Mode shapes and corresponding natural
frequencies
The mapping of sound pressure level (SPL)
and normal velocities before and after
modifications
xv
PAGE
60
73
CHAPTER I
INTRODUCTION
1.1 Background Studies
Noise reduction is an area of growing interest because of the need to reduce
noise in our community. In automotive industry, there are the problem of increases
in the cost of building and testing engines prototypes. At the same time there has
been a dramatic increase in the power and speed of digital computers. These two
factors have focused attention more and more on predictive techniques in all fields of
technical study as well as in noise reduction of engine field.
In the case of engine structure vibration and noise, a finite element method
(FEM) integrated with boundary element method (BEM) is now almost universally
used and the accuracy of prediction is continuing to improve as the technique
develops. According to Ulrich (1995), a finite element analysis for the structural
dynamic response integrated to a boundary element calculation is the best approach
and gives very satisfactory results for prediction of noise radiation problem.
It is of the greatest importance to incorporate low noise features into a new
design at the earliest possible stage and this is the intention of the study. This study
presents the initial stage in the development of a two-stroke gasoline engine
emphasizing more on vibration and noise reduction.
2
In Malaysia, almost 100% of two-stroke engine are imported. Many models
of motorcycles have been introduced, which have gained an overwhelming support
by Malaysians. Anyhow Malaysia's automotive industry was confined into
technology followers rather than technology leaders. Technology was basically
bought from foreigners and assimilated to local culture and needs. It is time for
Malaysian to seriously involve in automotive research and development, so engines
with purely local technology can be produced. Thus the purpose of this study is to
contribute positively to the whole process of development in automotive technology
in Malaysia. Moreover, the technology related to the producing of low noise two
stroke engine is still far away behind compared to other developing countries like
Japan, Korea and many more others. This is another reason why this study is carried
out.
1.2 Objectives of Project
The main objective of this project is to predict the noise level from the engine
surfaces. This is very important before any prototype of engine will be produced.
The second objective is to make some improvement and modification to the engine
structure to produce a low noise engine.
1.3 Scope
This project is limited to predict engine noise using numerical simulation
analysis by means of a finite element model and the boundary element method.
Component of engine considered is cylinder head. This cylinder head is one part of
'Single-Cylinder Two Stroke Compound Piston Engine' developed by Automotive
Development Centre, Universiti Teknologi Malaysia. No experimental analysis is
carried out.
3
CHAPTER II
INTRODUCTION TO BOUNDARY ELEMENT METHOD
This chapter introduces the basic theory of boundary element method (BEM)
and also an introduction to the finite element method (FEM). In numerical
simulation, the BE model is obtained from the coarsening of the FE model.
2.1 Boundary Element Method
The Boundary Element Method (BEM) is a relatively new numerical
technique which first appeared in scientific literature in 1977. The method is based
on boundary integral equations, which themselves have been investigated over a long
period. However, a discrete formulation and sufficient computer power were needed
to make the solution of these integral equations possible, especially in the case of
more complicated geometries.
From the beginning, boundary elements were a highly active field of research
within the engineering community. They quickly became an attractive alternative to