lamb wave propagation in plate with different depth …eprints.utem.edu.my/16657/1/lamb wave...

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LAMB WAVE PROPAGATION IN PLATE WITH DIFFERENT DEPTH OF

CORROSION DEFECT

NURUL FAHIMA BINTI MOHD KAMEL

This report submitted in partial fulfilment of the requirements for the award of

Bachelor of Mechanical Engineering (Structure and Material)

Faculty of Mechanical Engineering

Universiti Teknikal Malaysia Melaka

JUNE 2015

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DECLARATION

I declare that this report entitled “Lamb Wave Propagation in Plate with Different

Depth of Corrosion Defect” is the result of my own research except summaries and

quotations which have been acknowledged. The report has not been accepted for any

other degree and is not concurrently submitted in candidature of any other degree.

Signature : ....................................................................

Name : NURUL FAHIMA BINTI MOHD KAMEL

Date : ……..............................................................

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DEDICATION

Dedicated to my parents,

Mohd Kamel b Ibrahim & Hosnah Ismail

My supporting siblings,

Muhammad Fahmi Akmal bin Mohd Kamel

Nurul Fazilah binti Mohd Kamel

and

My entire friends in UTeM

For their encouragement

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ACKNOWLEDGEMENT

First of all, I would like to take this opportunity to express my gratefulness to

Allah s.w.t for blessing me with strength to complete this project. I would like to thanks

and acknowledge my supervisor, Dr. Nor Salim bin Muhammad for the guidance and

assistance throughout this project.

I also would like to thanks Final Year Undergraduate Project Coordinator,

Engr. Dr. Md. Fahmi bin Abd Samad @ Mahmood for the effort his put in providing

useful additional information and also guidance. Not to forget, to all the lecturers of

Structure and Material Department from Faculty of Mechanical Engineering whom

shared knowledge and valuable information to complete this research.

Most important of all, thanks to my family and fellow friends whom involved

directly or indirectly for their ever loving care towards the success of this study.

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ABSTRACT

Lamb wave propagation is one of the guided wave techniques that had been

rapidly develop in the industries especially for the inspection of thin plate structures.

Therefore, a study related on the Lamb wave propagation had carried out with the

purpose on investigating and analysing the wave propagation produced when the wave

is in contact with the defect on the thin plate. The plate modelling is perform using the

ABAQUS software and excitation of the wave propagation will be compare with the

experimental waveform propagation. Behaviour of the wave interaction with the defect

will be compared and discuss. The wave modes that are used in the case study are

symmetrical and anti-symmetrical modes which known as S0-mode and A0-mode

respectively. Both wave modes are excited in 6 mm aluminium plate using a 5 cycles

of tone burst signal at canter frequencies of 80 kHz, 100 kHz, and 120 kHz. The Lamb

wave propagation study covers the effect of the wave propagation when different

depths of rounded defects are applied. The study covers the investigation on effect

frequency and the defect orientation into the wave propagation in the plate structures.

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ABSTRAK

Penyebaran gelombang Lamb merupakan salah satu teknik gelombang

berpandu yang kian berkembang maju dalam industri terutamanya untuk memeriksa

struktur ke atas plat aluminium yang nipis. Oleh itu, satu kajian ke atas gelombang

Lamb telah dijalankan untuk melihat dan menganalisa kesan terhadap penyebaran

gelombang Lamb apabila melalui kawasan yang rosak atau cacat kesan dari hakisan

pada struktur plat. Proses permodelan plat aluminium dilakukan dengan menggunakan

simulasi ABAQUS untuk mendapatkan kesan penyebaran gelombang Lamb. Kesan

penyebaran Lamb secara simulasi akan dibandingkan dengan keputusan gelombang

yang diperoleh secara ujikaji yang sebenar iaitu pada plat aluminium sepanjang 1 m.

Kajian ini juga merangkumi kesan ke atas penyebaran gelombang apabila kedalaman

hakisan pada struktur plat, perbezaan frekuensi yang digunakan untuk menghasilkan

gelombang serta kedudukan hakisan pada plat aluminium. Selain itu, simulasi pada

plat dilakukan untuk mengetahui jenis mod gelombang yang digunakan dalamkajian

sam ada S0-mod mahupun A0-mod.

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TABLE OF CONTENTS

CHAPTER CONTENT PAGES

SUPERVISOR DECLARATION

AUTHOR DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENT vii

LIST OF TABLE ix

LIST OF FIGURE x

LIST OF SYMBOL xi

CHAPTER I INTRODUCTION

1.0 Overview

1.1 Background

1.1.1 Technique to Generate the Lamb Wave

Propagation Using Guided Wave

1.1.2 Lamb Wave Propagation

1.2 Advantages of Lamb Wave Propagation

1.3 Problem Statement

1.4 Objectives

1

1

2

3

4

5

5

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CHAPTER II LITERATURE REVIEW

2.0 Overview of Literature Review

2.1 Dispersion Curve of Phase Velocity and Group

Velocity

2.1.1 Dispersion Curve

2.1.2 Phase Velocity

2.1.3 Group Velocity

2.2 Symmetrical and Anti-symmetrical

2.3 Difference Between Guided Wave and

Ultrasonic Testing

2.4 Material Properties of Plate and Wedge Material

2.4.1 General and Mechanical Properties of

Aluminium plate

2.4.2 Wave properties of wedges

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6

7

8

10

11

13

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CHAPTER

III

METHODOLOGY

3.0 Overview of Methodology

3.1 Flowchart

3.2 Different Defects on the Wave Propagation

3.2.1 ABAQUS Simulation of Defect in

Aluminium Plate

3.3 Excitation of Lamb Wave Propagation

3.3.1 Wave Excitation on Different Frequencies

and Thickness

3.3.2 Wave Excitation on Different Geometry

and Orientation

3.3.2.1 Oval Defect

3.3.2.2 Round Defect

3.3.3 Wave Propagation Behaviour and Modes

Excitation

3.4 Excitation of Wave Based on Experimental

Work

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15

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18

19

19

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21

23

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3.5 Specification of the Lamb Wave Tools and

Apparatus

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CHAPTER

IV

RESULTS

4.0 Overview

4.1 Wave Propagation Through A Defected Groove

Structure For 1 m Aluminium Plate

4.1.1 Effect on Different Depth Thickness, h

at Frequency of 100 kHz

4.1.2 Effect on Different Sinewave

Frequency at Groove Depth of 4 mm

4.2 Wave Signal Through A Defected Groove

Structure for Fabricated 1 m Aluminium Plate

4.2.1 Wave signal through different thickness

of 100 kHz

4.2.2 Wave signal through different

frequency at 4 mm depth thickness

4.3 Wave Propagation and Signal Through A Defect

Structure for 5 m Aluminium Plate

4.3.1 Effect on Different Depth Thickness, h

at Frequency of 100 kHz

4.3.2 Effect on Frequency on 4 mm Groove

Defect Depth

4.3.3 Effect on Different Orientation at

Frequency of 100 kHz and Defect

Thickness of 4 mm

4.3.3.1 Oval Defect

4.3.3.2 Round Defect

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50

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CHAPTER

V

ANALYSIS AND DISCUSSIONS

5.0 Overview

5.1 Signal Behaviour on 1 m Aluminium Plate

5.1.1 Excitation of Different Defect Depth for

U1 and U3 Components

5.1.2 Excitation of the Excitation on Different

Frequency Signals For U1 and U3

Components

5.2 Wave Signal Behaviour Based on The

Experimental Testing

5.2.1 Comparison of wave signals for

experimental and simulation in the

different thickness of 1 m groove defect

5.2.2 Comparison of wave signals for

experimental and simulation in the

different frequency of 1 m groove defect

5.3 Signal Behaviour On 5 m Aluminium Plate

5.3.1 Excitation on Different Defect Depth

for U1 and U3 Components

5.3.2 Excitation of Different Frequency

Signals for U1 and U3 Components

5.3.3 Excitation on Different Orientations in

U1 and U3 Components

a) Oval defect

b) Round Defect

5.4 Relation Between A0-mode and S0-mode

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CHAPTER

VI

CONCLUSION AND RECOMMENDATIONS

6.1 Conclusion

6.2 Recommendation

103

104

BIBLIOGRAPHY 105

APPENDIX 108

BLANK PAGE 111

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LIST OF TABLES

NO. TITLE PAGES

2.1 Material properties of Aluminium Plate 12

2.2 Wave velocity properties for wedge 13

3.1 The specification and function of the Apparatus setup

for excitation of wave signals in 1m plate

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5.1 peak-to-peak value for A0-mode and S0-mode at

different depth thickness

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LIST OF FIGURES

NO. TITLE PAGES

1.1 Guided wave set up 3

2.1 Phase velocity and the frequency dispersion of the

dispersion curve

8

2.2 Group velocity and the frequency dispersion of the

dispersion curve

9

2.3 Anti-symmetrical mode 10

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2.3 Symmetrical mode 10

3.1 Flow chart of the research activities 15

3.2 Illustration of groove defect on 1 m aluminium plate 16

3.3 Illustration of groove defect on 5 m aluminium plate 17

3.4 Cross section of groove depth of defect in 2-Dimension

for 1 m and 5 m plate

17

3.5 Oval defect 10 mm x 200 mm in ABAQUS Simulation 19

3.6 Oval defect with different orientation 19

3.7 Round defect with four circle defects orientation 20

3.8 Round defect with multi flaw defects 20

3.9 Wave excitation behaviour when the signal is introduced 21

3.10 Force direction for S0-mode 22

3.11 Force direction for A0-mode 22

3.12 Fabricated of 40 mm groove defect with thickness of 2

mm, 3 mm and 4 mm of defect depth

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3.13 Block diagram to develop the excitation of wave signal in

1 m aluminium plate experiment testing

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3.14 Figure (a) and Figure (b) shows the apparatus setup for

the transmitter and receiver wave from the pulser

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3.15 The configuration for wave propagation excitation 26

4.1 Wave interaction behaviour when in contact with 2 mm

defect

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4.2

Figure (a) and Figure (b) shows the wave signal for

amplitude against time in U1 and U3 components for 2

mm depth

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4.3 Wave interaction behaviour when in contact with defect

at 3 mm depth

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4.4



mm depth

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for 4 mm depth

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4.6



mm depth

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for 5 mm depth

36

4.8



mm depth

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at 80 kHz

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4.10


amplitude against time in U1 and U3 components at

frequency of 80 kHz

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at 100 kHz 40

4.12



frequency of 100 kHz

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at 120 KHz

42

4.14



frequency of 120 kHz

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4.15 Signal wave for experimental depth defect testing in 1 m

aluminium plate for A0-mode

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aluminium plate for S0-mode

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aluminium plate for A0-mode

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aluminium plate for S0-mode

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4.19 Wave interaction behaviour for 2 mm thick groove defect

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4.20 Figure (a) and (b) are the wave interaction behaviour for

3 mm thick groove defect

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53


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55


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4.27 Wave interaction behaviour for frequency of 80 kHz 58


frequency of 80 kHz.

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4.29 Wave interaction behaviour for frequency of 100 KHz

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frequency of 100 kHz.

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4.31 Wave interaction behaviour for frequency of 120 KHz

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frequency of 120 kHz. 63

4.34 Wave interaction behaviour for axial (180 deg) oval

defect

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oval defect orientation.

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4.36 Wave interaction behaviour for axial defect (90 deg) 66


frequency of perpendicular defect

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4.38 Wave interaction for oblique defect (45 deg) 68

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frequency of perpendicular defect

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4.40 Wave interaction behaviour for 4 round defects 70


frequency of single round defects orientation

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4.42 Wave interaction behaviour for 2 round defects 72


double defects orientation

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4.44 Wave behaviour for 4 round defects orientation 74


4 round defects orientation

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5.1 Wave signals at U1 and U3 at different depth thickness in

1 m aluminium plate

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5.2 Wave computational results at U1 for different

thicknesses for 1 m aluminium plate

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thicknesses for 1 m aluminium plate

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5.4 Comparison of the wave signals with different

frequencies in 1 m plate

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5.5 Wave computational results at U1 for different frequency

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5.6 Wave computational results at U3 for different frequency

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5.7 Comparison of different depth thickness for experimental

and simulation for A0-mode

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5.8 Comparison of different depth thickness for experimental

and simulation for S0-mode

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5.9 Comparison of different frequencies for experimental and

simulation for A0-mode

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5.10 Comparison of different frequencies for experimental and

simulation for S0-mode

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5.11 Wave signals at U1 and U3 at different depth thickness in

5 m plate

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thicknesses

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thicknesses

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5.14 Wave signals at U1 and U3 at different frequency

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5.15 Wave computational results at U1 at different frequency

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5.16 Wave computational results at U3 at different frequency

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5.17 Wave signals at U1 and U3 at different oval orientation

defect 95

5.18 Wave computational results at U1 at different oval

orientation defect

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5.19 Wave computational results at U3 at different oval

orientation defect

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5.20 Wave signals at U1 and U3 at different round orientation

defect

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5.21 Wave computational results at U3 at different round

orientation defect

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5.22 Wave computational results at U3 at different round

orientation defect

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5.23 Method to calculate peak-to-peak (Vpp) values for S0-

mode and A0-mode for 2 mm depth thickness

100

5.24 The difference of amplitude between A0-mode and S0-

mode in 5 m aluminium plate

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5.25 The difference of amplitude between A0-mode and S0-

mode in 5 m aluminium plate

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LIST OF SYMBOL

𝑉𝑙 = group velocity of the incident longitudinal wave

𝑉𝑝 @ 𝑉∅ = phase velocity of the incident longitudinal phase

𝜑 = angle of the incident longitudinal wave

𝜔 = Angular velocity, rad/s

C = Wave speed of material, m/s

𝑘 = Wave number

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CHAPTER I

INTRODUCTION

1.0 OVERVIEW

This chapter will cover the overall introduction about the project background,

problem statement of the project, objectives, and the scope of the project.

1.1 BACKGROUND

The theory of Lamb waves was originally been developed by Horace Lamb in

1916 to describe the characteristics of waves propagating in plates. According to Rose

(2002), Lamb wave type propagation can travel not only in a thin plate but also in

multi-layer plates, rods, tubes, pipe and others where the components of vector can be

in parallel and perpendicular to the particle vibration in the vertical plane through the

structure. The Lamb wave opposed to the horizontal shear wave where the particle

motion is normal to the wave vector in a horizontal plane as the waves are propagates

through the plate structure. The Lamb waves referred to plate waves where it had been

introduce in guided wave propagation especially in the thin plate. The ability of the

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Lamb wave to travel in long distance to detect the defect within the plate (Shelke 2011)

currently had been experimented and analysed especially for non-destructive testing

(NDT). Therefore, when some high frequency wave is been shoot to the plate surface,

the wave will be reflect back toward the transducer and the defect can be observe. The

behaviour of the wave propagations is different due to the geometry and the thickness

of the plate structure (Salim et al. 2013). To study the wave propagation of the guided

wave, the piezoelectric transducer, wedges and also thin plate are needed to excite the

asymmetric and the symmetrical mode of the Lamb wave. Therefore, the reflected

wave will be observed and the flaw pattern are been studied.

1.1.1 Lamb Wave Propagation

Lamb waves can be generate in a plate with free boundaries with an infinite

number of modes for both symmetric and anti-symmetric displacements within the

layer. Lamb waves are similar to longitudinal waves, with compression

and rarefaction, but they are bind by the sheet or plate surface causing a wave-guide

effect.

The partial wave technique where wave propagation in plates is considers as a

combination of bulk waves that are reflecting between the boundaries of the plate. This

method provides insight into the physical nature of the Lamb waves. (Ghandhi 2010)

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1.1.2 Technique to Generate the Lamb Wave Propagation Using Guided Wave

There are two common techniques to generate the guided waves such as using

the angle beam transducer by pulsing a piezoelectric element on the wedge placed on

a test plate which had produce a different variety of waves propagated in the structure.

The piezoelectric will leads to the interference pattern of the wave vector. The second

technique is by using the comb transducer where a number of elements are place on

the structure with some spacing that pumps energy into the structure causing the

guided wave to propagate in both directions along the structure.

However, for this case, the technique used for the Lamb propagation is using

the angle beam transducer where the piezoelectric element and wedge are need.

Figure 1-1: Guided wave set up. (Source: Salim 2013)

The guided wave are consists of transducer, made by piezoelectric (PZT), and

also wedge so that the lamb wave can excite the symmetrical mode (S0-mode) and

asymmetrical mode (A0-mode) in plate so that the wave propagation can be observed

and analysed when propagates through the defects (Salim 2013). The basic guided

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setup can be refers in Figure 1.1. The wave can travel in a long inspection distance

where the frequencies for the S0-mode are between 80 kHz to 120 kHz using acrylic

whereas; A0-mode is being excited using the aqualene wedge.

When the Lamb wave propagate through the plate, the defect can be detect

based on the dispersion curve based on the frequency used, therefore the behaviour of

the defect can be measured and analysed (Takahiro et al.2012). The Lamb waves often

refer as the plate wave where the component of the extensional wave is perpendicular

to the surface. The waves are generated when the longitudinal waves are intersects

with a surface and it is very sensitive to a defects. Therefore, as the lamb wave can

travel in a long distance, the defects can easily detected even the spaces are narrow

and difficult to reach.

1.2 ADVANTAGES OF LAMB WAVE PROPAGATION

.

The most important benefit of the guided wave using Lamb wave propagation

is that the inspection area for the specimen in thin plate or pipe will be increase

compared to the Ultrasonic testing technique. The wave propagation of the guided

wave can travel in a long distance with low attenuation. Therefore, most of narrow part

or extremely large area can be inspect easily in a short time. Hence, the defect can be

easily be spotted using the guided Lamb wave propagation.

In addition, using the Lamb wave propagation, the inspected area of plate can

be screened easily using several transducers for the wave excitation. Hence, this

technique will significantly will reduce the time preparation and the work force to do

the inspection testing for industrial purpose.

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For the industrial cases or in a plant, the guided lamb wave techniques are

important to detect the defect on the thin wall of the structure. Hence, any signal

produce on the monitor will signifies the defect on the structure. After all, the

inspection using the Lamb wave are useful as it will gives such a comprehensive

condition information about the defect or crack in or on the structure immediately.

1.3 PROBLEM STATEMENT

Guided wave inspection had been one of the latest techniques in non-

destructive test (NDT) and material evaluation. The propagation of the guided wave

such as Lamb wave are used to detect the defect on the surface structures especially

on the thin plate and reflects the echoes when the defect are detected. The surface

defect can be known when the high frequency of wave is pointed on certain location

of the plate or thin surface. The suitable selection of the guided mode and frequency

range are important for the inspection to be succeeded. As the guided wave

propagation of Lamb wave are still being develop, the potential of guided wave

inspection using Lamb wave propagation to detect the defect are still not being used

domestically in plant and industry. However, the misinterpretation from inexperience

NDT staff might leads to the miss-defect during site inspection. Therefore, this study

will investigate the behavior of wave interaction with different types of defect.

1.4 OBJECTIVES

The objectives in this study are;

1. To study the effect of defect geometries, depths, and orientations on guided wave

propagation.

2. To verify depend of frequency on guided wave propagation.

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CHAPTER II

LITERITURE REVIEW

2.0 OVERVIEW

This chapter will focus on the dispersion curve and the beam focusing on the

guided waves of Lamb Wave propagation. The review are gathered based on the past

research from the journals, technical papers, reference books, which related article on

guided waves of Lamb Wave propagation.

2.1 DISPERSION CURVE OF PHASE VELOCITY AND GROUP

VELOCITY

2.1.1 Dispersion Curve

Based on Rose (2013) in Materials Evaluation, the dispersion curve can be

relate by the relation between the phase velocity and the frequency or the frequency

and thickness of the plate structure. Dispersion curve shows all the constructive

interference zones that could be create as the waves are reflected inside a structure,

lamb wave propagation in plate with different depth …eprints.utem.edu.my/16657/1/lamb wave...

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