MOHD ZUL-HILMI BIN MOHAMAD

Transcription

1 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

2 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:

3 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

4 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 Introduction Problem Statement Objective of The Project 3 CHAPTER 2 LITERATURE REVIEW Introduction Acoustic Emission (AE) Acoustic Emission Technique Acoustic Emission signal Parameters Wavelet Wavelet Transform 9

5 viii 2.5 Shannon Wavelet Theory Shannon Wavelet Wavelet Packets Wavelet Packet Analysis Type of Wavelet Haar Wavelet Morlet Wavelet Coiflet Wavelet Daubechies Wavelet Mexican Hat Wavelet CHAPTER 3 METHODOLOGY Introduction Flow Chart Methodology Flow Chart Gantt Chart Signal Analysis Methodology De-noising of Signal Signal Analysis Step for De-noising Proces CHAPTER 4 RESULT AND DISCUSSION Introduction De-noising Acoustic Emission Data (I) De-noising Acoustic Emission Data (II) 37 CHAPTER 5 CONCLUSION Conclusion 5.2 Suggestion 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

6 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 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 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

7 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 Value of AE Parameter for Smooth Surface Pipe Bangi number value for rough pipe Bangi number value for smooth pipe Bangi number value from (M.H.Zohari,2008)

8 xi List of Figures Figure No. Page 2.1 Acoustic Emission Testing Acoustic Emission signal Parameters Demonstration of (a) a Wave and (b) a Wavelet 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 The wavelet packet decomposition using operator notations The comparison between (a) a time-scale tiling plane of wavelets and (b) wavelet packets The Haar wavelet Real (a) and imaginary part (b) of the Morlet wavelet for z 0 = Coiflet wavelet (a) Father function and (b) Wavelet function Mother wavelet functions DB4, and DB8, respectively The Mexican Hat wavelet Import an AE data into Matlab Wavelet Packet 1-D in Wavelet Tool Box 30

9 xii 3.3 Import AE Signal into Wavelet Packet 1-D Setting the Parameter to De-Noise the Signal Analyse the Signal AE Signal Before and after De-noising Process Example of setting that used to de-noise the acoustic emission data 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 Energy of Rough Pipe for (a) high flow rate and (b) low flow rate 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 Energy of Smooth Pipe for (a) high flow rate and (b) low flow rate 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

10 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