automotive engine fault diagnosis using acoustic emission...

AUTOMOTIVE ENGINE FAULT DIAGNOSIS USING ACOUSTIC EMISSION TECHNIQUE

NUR NAQUIAH BINTI MOHAMMAD ALI

Thesis submitted in fulfilment of the requirements for the award of the degree of

Bachelor of Mechanical Engineering with Automotive Engineering

Faculty of Mechanical Engineering UNIVERSITI MALAYSIA PAHANG

DECEMBER 2010

ii

UNIVERSITI MALAYSIA PAHANG

FACULTY OF MECHANICAL ENGINEERING

I certify that the project entitled “Automotive Engine Fault Diagnosis Using Acoustic

Emission Technique” is written by Nur Naquiah Binti Mohammad Ali. I have examined

the final copy of this project and in my opinion; it is fully adequate in terms of scope and

quality for the award of the degree of Bachelor of Engineering. I herewith recommend that

it be accepted in partial fulfillment of the requirements for the degree of Bachelor of

Mechanical Engineering with Automotive Engineering.

(DR GIGIH PRIYANDOKO)

Examiner Signature

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SUPERVISOR’S DECLARATION

I hereby declare that I have checked this project and in my opinion, this project is adequate

in terms of scope and quality for the award of the degree of Bachelor of Mechanical

Engineering with Automotive Engineering.

Signature:

Name of Supervisor: MR MOHD HAFIZI BIN ZOHARI

Position: LECTURER

Date: 06 DECEMBER 2010

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STUDENT’S DECLARATION

I hereby declare that the work in this project is my own except for quotations and

summaries which have been duly acknowledge. The project has not been accepted for any

degree and is not concurently submitted for award of other degree.

Signature:

Name: NUR NAQUIAH BINTI MOHAMMAD ALI

ID Number: MH07020

Date: 06 DECEMBER 2010

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ACKNOWLEDGEMENTS

I would like to express my deepest gratitude to Allah SWT for guiding me to conceptualize, design, and complete this project. Special thanks to my very understanding and kind project’s supervisor, Mr Mohd Hafizi Bin Zohari for your suggestions and advices that really encourage me throughout the project. I would also like to express my appreciation to Mr Faizul Syahidan for helping me in setting up the test-rig, giving me a lot of information and guidance especially on the technical stuff. Also special thanks to all my course mates for giving me supports and motivations throughout this project. To my parents, Mohammad Ali Ahmad and Latipah Yusop, thank you for being a very great supporters and motivators. Finally, I want to thank all people who involve directly and indirectly in this project.

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ABSTRACT

This thesis was carried out to diagnose faults in an automotive engine using acoustic emission method. Proton Persona’s engine, which is a four cylinder engine, powered by 1.6 liters double overhead camshaft (DOHC) with two different locations (Point A and Point B) marked was used as the main test-rig. There were three tests conducted for this project, the pencil-break test, engine under idle condition and engine under fuel injector shut off condition. Pencil-break test is performed in order to check the most suitable material to be used as medium to transfer the signals. The source of the Acoustic Emission (AE) signals was from the condition where the fuel injector was shut off when the engine is running, and it was captured using AE sensor with the help from Physical Acoustic AE-win 3.1 software. For engine under idle and shut off condition, all the domain parameters (RMS amplitude, peak amplitude and energy) was processed using MATLAB software. The parameters were then compared between idle and shut off condition for each fuel injector shut off. The results shows that the different of AE parameters between Point A and Point B, where Point B shows higher value than Point A in idle condition and also under fuel injector shut off condition. During shut off condition, the RMS amplitude, peak amplitude and energy produced higher energy level compare to idle condition. This indicates defects or faults occurred. In addition, Pekan number, X was introduced as the indicator or ratio of value before fuel injector shut off to value during fuel injector shut off.

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ABSTRAK

Tesis ini dijalankan untuk menjalankan diagnosis terhadap kegagalan enjin automotif dengan menggunakan teknik pancaran akustik. Enjin yang digunakan sebagai rig ujikaji utama ialah enjin kereta Proton Persona, empat silinder, dikuaskan oleh 1.6 liter aci sesendol (DOHC) yang telah ditanda di dua titik berlainan. Tiga ujian telah dijalankan di dalam projeck ini iaitu ujian pematahan pensil, ujian enjin di dalam keadaan normal dan keadaan enjin apabila penyuntik bahan bakar ditutup. Ujian pematahan pensil dijalankan untuk melakukan cek ke atas bahan paling sesuai dijadikan medium keterhantaran isyarat. Punca isyarat pancaran akustik (AE) adalah daripada keadaan di mana penyunyik bahan bakar ditutup semasa enjin masih lagi dihidupkan, dan ianya kemudian dicerap dengan menggunakan penderia akustik dibantu dengan paparan perisian Physical Acoustic AE-win 3.1. untuk keadaan dimana enjin berada dalam keadaan normal dan ketika penyuntik bahan bakar ditutup, kesemua nilai parameter domain masa (amplitude pmkd, amplitude maksimum dan tenaga) dari isyarat yang dicerap, diproses dengan bantuan perisian MATLAB. Kesemua parameter tersebut kemudian dibandingkan di antara keadaan enjin normal dengan keadaan enjin apabila penyuntik bahan bakar ditutup, untuk setiap penyunyik bahan bakar. Hasil menunjukkan perbezaan nilai parameter domain masa di antara titik A dengan titik , dimana nilai titik B lebih tinggi semasa keadaan enjin normal dan ketika penyuntik bahan bakar ditutup. Semasa penyuntik bahan bakar ditutup, parameter domain masa menghasilkan nilai yang lebih tinggi berbanding keadaan enjin normal. Ini membuktikan wujudnya kegagalan di dalam enjin tersebut. Di samping itu, angka Pekan, X diperkenalkan sebagai penunjuk dimana nilai parameter domain ketika keadaan enjin normal dibahagi dengan nilai parameter domain ketika penyuntik bahan bakar ditutup.

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TABLE OF CONTENTS

Page

EXAMINER SIGNATURE ii

SUPERVISOR’S DECLARATION iii

STUDENT’S DECLARATION iv

ACKNOWLEDGEMENTS v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENTS viii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF SYMBOLS xv

LIST OF ABBREVIATIONS xvi

CHAPTER 1 INTRODUCTION

1.1 Problem Statement 3

1.2 Objective 3

1.3

1.4

Scope

Limitation

4

4

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 5

2.2 Steel

2.2.1 Types of Steel

6

6

2.3 Aluminium 8

2.4 Engine

2.4.1 Types of Piston-Engines 2.4.2 Engine Operation

8

9 11

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2.4.2.1 Four-Stroke Cycle 2.4.2.2 Two-Stroke Cycle

2.4.3 Cylinder Block

2.4.3.1 Combustion Chamber 2.4.3.2 Fuel Injection System

12 13

15

15 16

2.5 Acoustic Emission 18

2.5.1 Phenomena of Acoustic Emission 2.5.2 Acoustic Emission Method 2.5.3 Acoustic Emission Components

18 20 21

2.6

2.5.3 Acoustic Emission Components

Review of Studies About Acoustic Emission Testing

21

22

CHAPTER 3 METHODOLOGY

3.1 Introduction 24

3.2 Flow Chart 24

3.3 Test Rig Preparation

3.3.1 Materials and Tools Preparation 3.3.2 Engine Specification 3.3.3 Semi Anechoic Chamber 3.3.4 Acoustic Emission System Specification 3.3.5 Carman Scan Specification

26

27 29 30 31 32

3.4 Data Acquisition 33

3.5 Experiment Procedure 33

CHAPTER 4

RESULTS AND DISCUSSION

4.1 Introduction 37

4.2 Pencil Break Test

4.2.1 Pencil Break Test Without Adapter 4.2.2 Pencil Break Test Using Aluminium Adapter 4.2.3 Pencil Break Test Using Mild Steel Adapter

38

38 38 38

x

4.2.4 Pencil Break Test Using Stainless Steel Adapter 39

4.3 Engine Under Idle Condition 40

4.4 Engine Under Fuel Injector Shut Off Condition

4.4.1 Fuel Injector 1 Shut Off 4.4.2 Fuel Injector 2 Shut Off 4.4.3 Fuel Injector 3 Shut Off 4.4.4 Fuel Injector 4 Shut Off

45

46 51 55 60

CHAPTER 5 CONCLUSION

5.1 Conclusion 68

5.2 Recommendation

70

REFERENCES 72

APPENDICES 75

A1 Test data: Pencil break test without adapter 75

A2 Test data: Pencil break test using mild steel adapter 76

A3 Test data: Pencil break test using aluminium adapter 77

A4 Test data: Pencil break test using stainless steel adapter 78

A5 List of command for signal analysis using MATLAB 79

A6 Gantt chart for Final Year Project 2

80

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LIST OF TABLES

Table No.

Title Page

3.1

Pencil Hardness Rating 28

3.2 Points where measurements taken 36 4.1

Average value of RMS, peak amplitude and energy for Point A and Point B

43

4.2

Pekan number values for fuel injector 1 shut off 65

4.3 Pekan number values for fuel injector 2 shut off 66 4.4 Pekan number values for fuel injector 3 shut off 66 4.5 Pekan number values for fuel injector 4 shut off 66 5.1 Pekan number, X for automotive engine condition 69

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LIST OF FIGURES

Figure No. Title Page

2.1 Spark Ignition 9

2.2 Compression Ignition 10

2.3 (a) SI sparks 11

(b) CI sparks 11

2.4 4-strokes cycle 13

2.5 2-strokes cycle 14

2.6 Combustion chamber of a 4-strokes cycle 16

2.7 Fuel injector component 17

2.8 (a) Burst signal 19

(b) Continuous signal 19

2.9 Acoustic Emission System measurement 20

3.1 Flow chart 25

3.2 Experiment design layout 26

3.3 Dimension of adapter 27

3.4 Pencil Break Test 28

3.5 Proton Persona with CAMPRO engine 29

3.6 Semi Anechoic Chamber 30

3.7 USB AE Node System 31

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3.8 Carman Scan 32

3.9 (a) Location marked Point A 34

(b) Location marked Point B 34

4.1 Average powers of different materials for adapter 39

4.2 Average voltages of different materials for adapter 40

4.3 RMS amplitude for Point A (left) and Point B (right) 41

4.4 Peak amplitude for Point A (left) and Point B (right) 42

4.5 Energy for Point A (left) and Point B (right) 42

4.6 Comparison for RMS amplitude between Point A and Point B 44

4.7 Comparison for Peak amplitude between Point A and Point B 44

4.8 Comparison for energy value between Point A and Point B 45

4.9 Raw RMS amplitude for Point A (left) and Point B (right) 47

4.10 Average RMS amplitude for Point A (left) and Point B (right) 47

4.11 Raw peak amplitude for Point A (left) and Point B (right) 48

4.12 Average peak amplitude for Point A (left) and Point B (right) 49

4.13 Raw energy value for Point A (left) and Point B (right) 50

4.14 Average energy value for Point A (left) and Point B (right) 50





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5.1 New Test Rig 71

xv

LIST OF SYMBOLS

kW Kilo watt Nm Newton per metre Rpm Revolution per minute X Pekan number (Angka Pekan)

xvi

LIST OF ABBREVIATIONS

A/D Analog to Digital AE Acoustic Emission AET Acoustic Emission Technique ASTM American Society of Testing and Materials Campro Cam Profiling

CI Compression Ignition DOHC Double Overhead Camshaft HSDI High Speed Direct Injection ICE Internal Combustion Engine NDT Non-Destructive Technique NVH Noise, Vibration and Harness RMS Root Mean Square SMA Shape memory alloys

CHAPTER 1

INTRODUCTION

Today, automobile are important parts of average family life. Alongside their wider

use and mass production, demand is increasing for high performance and safe vehicle.

Maintaining a high level of engine reliability by efficient fault diagnosis is thus becoming

important for several reasons. Firstly, the downtime of the engine is expensive. Secondly,

certain malfunctioning conditions can be a threat to safety of both the human beings and the

environment. Accordingly, the large number of cars on the roads has lead to legislative and

regulatory of certain nations. In response to these and other demands, systematic defaults of

engine detection have long been sought.

In automobile engine, when the engine is running, the piston in the cylinder will

move upward and downward in order to make a complete revolution to combust and

produced energy. Therefore, vibration is created in the combustion chamber between the

sliding of the piston with the wall. This then burst into acoustic emission. Characteristics

and the condition of the automobile engine can be identified using the sound wave

produced by the vibration. So, the objective of this research is to measure the amount of

Acoustic Emission signals which consists of amplitude, hits and rms of the wave.

2

The classical auto diagnostic solutions that most garages were using years before

were based on measurements of physical parameters such as temperature, flow and

resistance (Roussat et al., 1990). In certain rare cases, auto diagnostic code readers of

electronic controls units or ECU are used on the latest automobiles. Computer microchip of

ECUs can store a diagnostic trouble code if certain problems occur in the engine. However,

the stored trouble code does not always identify the cause of the problems (Gelgele et al.,

1996). At this higher level of information-age technology has made it possible to diagnose

the engine’s fault and get accurate data but at the same time, did not affect the engine. The

best way is to use non-destructive testing technique which can acquire sets of data without

disassembly the engine. The concept of this method is by comparing the input and output to

analyze the design without damaging the physical state of the model and to analyze the

defects. Other non-destructive techniques that we can use are vibration analysis, laser

testing, magnetic particle testing, and thermal or infrared method.

One of the most interesting techniques used for the non-destructive evaluation of

materials is the Acoustic Emission Technique (AET). The Acoustic Emission Non-

Destructive Technique is based on the detection and conversion of these high frequency

elastic waves to electrical signals. Compared to other non-destructive testing (NDT)

methods, AET can monitor changes in materials behaviour over a long time and without

moving one of its components such as sensors. This technique is quite unique along with

the ability to detect crack propagations occurring not only on the surface but also deep

inside a material.

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1.1 PROBLEM STATEMENT

Engine is a medium of transferring energy by providing an input power to the

machine especially the car. Engine can be said as the ‘heart’ of the car. A vehicle cannot

run without any engine in it. So it is very crucial to take a good care of it so that its lifespan

will be longer and we at the same time maintain its performance. In this study, we want to

diagnose and determine the performance of the engine without disassembly it. The best

way is by using Non-Destructive method.

Problem statements of this study are to measure the AE signal when one of the fuel

injector is shut off .In order to do this, an adapter will first be pointed at certain point on the

cylinder block and shutting off one of the fuel injector, at times when the engine is running.

The sets of data that will be collected are use to analyze the relationship between the

parameters.

1.2 OBJECTIVE

The objectives of this project are:

1. To design and fabricate an adapter for Acoustic Emission (AE) signals

2. To diagnose engine fault using AE signals

3. To determine the correlation between AE signals and engine fault when fuel

injector is shutoff.

4

1.3 SCOPE

Scope of the project is important as it will act as a guidance to make sure that the

research is done towards the right direction and to construct the objective perfectly. In this

study, Acoustic Emission Technique (AET) was used as a main non-destructive method to

diagnose and monitor the engine’s performance. In order to design and fabricate the

adapter, different materials were used to fabricate it and we will focus on the type of

material only instead of the length, diameter, etc. To check the suitability of the material

used, pencil break test is conducted. In this study also, we had interpret the character of the

engine and the processes which the fuel injector was shut off while the engine is running.

This was the main condition in determining the performance of the engine. Theoretically,

the engine will have different load acting on it if there is a fault such as when the fuel

injector is shut off. Every time the fuel injector is shut off, the time and AE signal of the

engine are recorded and diagnosed.

1.4 LIMITATION

This study requires designing and fabricating an adapter that are adapted to the

acoustic emission sensor of the main apparatus. The materials that were used in fabricating

this adapter are aluminium, stainless steel and mild steel that are provided in the lab. In

order to check the suitability of the material used, pencil break test is conducted first before

proceeding to the next step.

In this research, automotive engine that had been used was the Proton Persona’s

engine, manufactured by Proton. It is a four cylinder engine that powered by 1.6 liters

double overhead camshaft engine (DOHC). The transmission system consists of five-speed

manual drive gearbox and comes with 16 valves of intake and exhaust valves. The engine

produces a peak power of 82kW at 6000 rpm and a maximum torque of 148Nm at 4000

rpm.

5

CHAPTER 2

LITERATURE REVIEW

2.1 INTRODUCTION

The objective of this chapter is to give a brief about some overview information

regarding the materials that will be used to fabricate the adapter which are Steel and

Aluminium. In addition, a briefing on its suitability and also the car’s engine subjected to

acoustic emission. Furthermore, to discuss about the engine and a few components that are

integrated to the internal combustion chamber and the principle of Acoustic Emission.

Using many references from various sources such as journals, thesis, reference books and

reading from the internet, this project’s literature review has been carry out to gather all

information that is related to this project.

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2.2 STEEL

Steel is one of the materials that were used to fabricate the adapter. This adapter

along with the sensor will be pointing out on certain location on the combustion chamber.

This will be done in order to transmit the signal produced by the combustion chamber.

Steel can be defined generally as hard, strong, durable, malleable alloy of iron and carbon,

usually containing between 0.2 and 1.5 percent carbon, often with other constituents such

as manganese, chromium, nickel, molybdenum, copper, tungsten, cobalt, or silicon,

depending on the desired alloy properties, and widely used as a structural material. To be

very precise, steel is defined as Alloy of iron and about 2% or less carbon.

The three major classes are carbon steels, low-alloy steels, and high-alloy steels.

Low-alloy steels, with up to 8% alloying elements are exceptionally strong and are used for

machine parts, aircraft landing gear, shafts, hand tools, and gears, and in buildings and

bridges. High-alloy steels, with more than 8% alloying elements such as stainless steels that

offer unusual properties.

2.2.1 Types of Steel

In this subchapter, types of steel that will be used is explained. There are two types

of steel that will be used to design and fabricate the adapter in this project, which is Mild

Steel and Stainless Steel.

Carbon steel is sometimes referred to as 'mild steel' or 'plain carbon steel'. The

American Iron and Steel Institute defines a carbon steel as having no more than 2 % carbon

and no other appreciable alloying element. Carbon steel makes up the largest part of steel

production and is used in a vast range of applications.

Typically carbon steels are stiff and strong. They also exhibit ferromagnetism as

they are magnetic. This means they are extensively used in motors and electrical

appliances. The corrosion resistance of carbon steels is poor, rust and so they should not be

used in a corrosive environment unless some form of protective coating is used.

7

Stainless steel is the universal name for a number of different steels used primarily

for their anti-corrosive element. Stainless steel has been developed to resist a number of

corrosive environments. It ensures that our workplaces are safe, that buildings last longer

and that our food preparation surfaces are hygienic. It is also an earth friendly material; it

can be melted down, recycled and made into something else.

Stainless steel is made using chromium. The minimum amount of chromium used to

make stainless steel is 10.5%; it is chromium that makes the steel stainless. Chromium also

improves the corrosion resistance by forming a chromium oxide film on the steel. This very

thin layer, when placed under the right conditions, can also be self-repairing.

There are other elements used to make stainless steel as well, including nickel,

nitrogen and molybdenum. Bringing these elements together forms different crystal

structures that enable a variety of properties in machining, welding and forming.

Stainless steel is a very versatile material. It can literally be used for years and

remain stainless. Stainless steel products have a significantly longer lifespan than products

made of other materials. There are less maintenance costs, and stainless steel also has a

very high scrap value on decommissioning.

8

2.3 ALUMINIUM

Other than steel, aluminium is one of the materials chosen in fabricating the adapter.

Aluminium was first produced in 1825. It is the most abundant metallic element, making up

about 8% of the Earth’s crust and is produced in a quantity second only to that of iron. The

principal ore of aluminium is bauxite, which is a hydrous that contains water-containing

aluminium oxide and includes various other oxides.

Aluminium is first produced after the clay and dirt are washed- off, the ore is

crushed into powder and treated with hot caustic soda to remove impurities. Alumina or

aluminium oxide is extracted from this solution and then dissolved in a molten sodium-

fluoride and aluminium-fluoride bath at 940 to 980℃ and the subjected to electrolysis.

Aluminium is formed at cathode while oxygen is released at anode. The production process

consumes a great deal of electricity, which contributes significantly to the cost of

aluminium.

Pure aluminium is up to 99.99% of aluminium, also referred to industry as “four

nines” aluminium. The characteristics of this nonferrous metal are the high strength-to-

weight ratio, resistance to corrosion, high thermal and electrical conductivity, non-toxicity,

reflectivity, appearance and ease of formability and of machinability and non-magnetic.

2.4 ENGINE

An engine is a machine that converts heat energy into mechanical energy. The heat

from burning a fuel produces power which moves the vehicle. Sometimes, the engine is

called the power plant.

Automotive engines are internal-combustion engines (ICE) because the fuel that

runs them is burned internally, or inside the engines. There are two types of engine,

reciprocating and rotary. Reciprocating can be explained by moving up and down or back

and forth. Most automotive engines are reciprocating. They have pistons that move up and

automotive engine fault diagnosis using acoustic emission...

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