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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


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.


(Tandatangan penyelia sebagai saksi)

Nama pcnycJia:

PM. DR. ROSLAN ABDUL RAHMAN

Fakulti: Kejuruteraan Mekanikal


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


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


at 2000 rpm 54


at 2500 rpm 54

6.6 Maximum normal velocities at 1500 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



4.5 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



6.6(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

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