i DE-NOISING OF AN EXPERIMENTAL ACOUSTIC EMISSIONS (AE) DATA USING ONE DIMENSIONAL (1-D) WAVELET PACKET ANALYSIS MOHD ZUL-HILMI BIN MOHAMAD Report submitted in partial fulfillment of the requirements for the award of Bachelor of Mechanical Engineering with Automotive Faculty of Mechanical Engineering UNIVERSITI MALAYSIA PAHANG NOVEMBER 2009
ii SUPERVISOR S DECLARATION We hereby declare that we have checked this project report and in our opinion this project is satisfactory in terms of scope and quality for the award of the degree of Bachelor of Mechanical Engineering with specialization. Signature: Name of Supervisor: Position: Date: Signature: Name of Panel: Position: Date:
iii STUDENT S DECLARATION I hereby declare that the work in this report is my own except for quotations and summaries which have been duly acknowledged. The report has not been accepted for any degree and is not concurrently submitted for award of other degree. Signature: Name: MOHD ZUL-HILMI BIN MOHAMAD ID Number: MH06022 Date: 31 NOVEMBER 2009
vii TABLE OF CONTNTS Page SUPERVISOR S DECLARATION STUDENT S DECLARATION ACKNOWLEDGEMENTS ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS ii iii iv v vi vii x xi xiii CHAPTER 1 INTRODUCTION 1 1.1 Introduction 1 1.2 Problem Statement 3 1.3 Objective of The Project 3 CHAPTER 2 LITERATURE REVIEW 4 2.1 Introduction 4 2.2 Acoustic Emission (AE) 4 2.2.1 Acoustic Emission Technique 5 2.2.2 Acoustic Emission signal Parameters 6 2.3 Wavelet 7 2.4 Wavelet Transform 9
viii 2.5 Shannon Wavelet Theory 10 2.5.1 Shannon Wavelet 10 2.6 Wavelet Packets 13 2.7 Wavelet Packet Analysis 15 2.8 Type of Wavelet 2.8.1 Haar Wavelet 2.8.2 Morlet Wavelet 2.8.3 Coiflet Wavelet 2.8.4 Daubechies Wavelet 2.8.5 Mexican Hat Wavelet 17 17 18 20 20 22 CHAPTER 3 METHODOLOGY 24 3.1 Introduction 24 3.2 Flow Chart Methodology 24 3.2.1 Flow Chart 25 3.3 Gantt Chart 26 3.4 Signal Analysis Methodology 3.4.1 De-noising of Signal 3.4.2 Signal Analysis 3.4.3 Step for De-noising Proces CHAPTER 4 RESULT AND DISCUSSION 33 27 27 27 29 4.1 Introduction 33 4.2 De-noising Acoustic Emission Data (I) 33 4.3 De-noising Acoustic Emission Data (II) 37 CHAPTER 5 CONCLUSION 50 5.1 Conclusion 5.2 Suggestion 51 51 REFERENCES 52 APPENDIX 1 List Of Command For Signal Analysis Using MATLAB 54 APPENDIX 2 Peak Amplitude Value (In Unit Volt) for db3 for Rough Pipe in High Flow Rate 55
ix RMS Value (In Unit Volt) for db3 for Rough Pipe in High Flow Rate Energy Value (In Unit Joule) for db3 for Rough Pipe in High Flow Rate Peak Amplitude Value (In Unit Volt) for db3 for Rough Pipe in Low Flow Rate RMS Value (In Unit Volt) for db3 for Rough Pipe in Low Flow Rate Energy Value (In Unit Joule) for db3 for Rough Pipe in Low Flow Rate 57 59 61 63 65 Peak Amplitude Value (In Unit Volt) for db3 for Smooth Pipe in High Flow Rate RMS Value (In Unit Volt) for db3 for Smooth Pipe in High Flow Rate Energy Value (In Unit Joule) for db3 for Smooth Pipe in High Flow Rate 67 69 71 Peak Amplitude Value (In Unit Volt) for db3 for Smooth Pipe in Low Flow Rate RMS Value (In Unit Volt) for db3 for Smooth Pipe in Low Flow Rate 73 75
x List of Tables Table No. Page 4.1 Result From De-Noising Process (Energy Lost After De-Noising 35 Process) 4.2 Value of AE Parameter for Rough Surface Pipe 38 4.3 Value of AE Parameter for Smooth Surface Pipe 42 4.4 Bangi number value for rough pipe 48 4.5 Bangi number value for smooth pipe 48 4.6 Bangi number value from (M.H.Zohari,2008)
xi List of Figures Figure No. Page 2.1 Acoustic Emission Testing 5 2.2 Acoustic Emission signal Parameters 6 2.3 Demonstration of (a) a Wave and (b) a Wavelet 7 2.4 A (a) Test-3 data and (b) de-noised data showing signal from rubbing of fasteners. 2.5 Shannon scaling function φ(x) (thick line) and wavelet (dashed line) ψ(x) 2.6 (a) Wavelet packets decomposition tree. (b) An example of an orthogonal basis tree with wavelet packets decomposition 8 12 13 2.7 The wavelet packet decomposition using operator notations 15 2.8 The comparison between (a) a time-scale tiling plane of wavelets and (b) wavelet packets 16 2.9 The Haar wavelet 18 2.10 Real (a) and imaginary part (b) of the Morlet wavelet for z 0 = 5. 19 2.11 Coiflet wavelet (a) Father function and (b) Wavelet function 20 2.12 Mother wavelet functions DB4, and DB8, respectively. 21 2.13 The Mexican Hat wavelet 23 3.1 Import an AE data into Matlab 30 3.2 Wavelet Packet 1-D in Wavelet Tool Box 30
xii 3.3 Import AE Signal into Wavelet Packet 1-D 31 3.4 Setting the Parameter to De-Noise the Signal 31 3.5 Analyse the Signal 32 3.6 AE Signal Before and after De-noising Process 32 4.1 Example of setting that used to de-noise the acoustic emission data 34 4.2 Peak Amplitude of Rough Pipe for (a) high flow rate and (b) low flow rate 4.3 RMS amplitude of Rough Pipe for (a) high flow rate and (b) low flow rate 39 40 4.4 Energy of Rough Pipe for (a) high flow rate and (b) low flow rate 41 4.5 Peak Amplitude of Smooth Pipe for (a) high flow rate and (b) low flow rate 4.6 RMS amplitude of Smooth Pipe for (a) high flow rate and (b) low flow rate 43 44 4.7 Energy of Smooth Pipe for (a) high flow rate and (b) low flow rate 45 4.8 Comparison of Bangi number plot for peak amplitude from a) previous result and (b) the latest result 4.9 Comparison of Bangi number plot for RMS amplitude from a) previous result and (b) the latest result 4.10 Comparison of Bangi number plot for energy from a) previous result and (b) the latest result 46 47 47
xiii LIST OF ABBREVIATIONS 1-D One Dimensional AE AET CWT db DWT FFT NDT RMS STFT WFT WPA WT Acoustic Emission Acoustic Emission Technique Continues Wavelet Transformation Daubechies Discrete Wavelet Transformation Fast Fourier Transform Non-destructive Testing Root Mean Square Short-Time Fourier Transform Windows Fourier Transform Wavelet Packet Analysis Wavelet Transform