1BI09MMD17

VISVESVARAYA TECHNOLOGICAL UNIVERSITY VISVESVARAYA TECHNOLOGICAL UNIVERSITY

“Jnana Sangama”, Belgaum-590014, Karnataka

A Seminar Report on

“ULTRASONIC TECHNIQUES FOR HIDDEN CORROSION DETECTION”

Submitted in partial fulfillment of the requirement for the award of the degree of

MASTER OF TECHNOLOGY MASTER OF TECHNOLOGYIn

MACHINE DESIGN MACHINE DESIGNBy

THEJAS NUnder the guidance of

Dr.M.Venkatarama ReddyDr.M.Venkatarama Reddy Professor and Head, Professor and Head,

Dept. of Mechanical EngineeringDept. of Mechanical EngineeringBIT, BangaloreBIT, Bangalore

Department of Mechanical EngineeringDepartment of Mechanical EngineeringBANGALORE INSTITUTE OF TECHNOLOGYBANGALORE INSTITUTE OF TECHNOLOGY

K R Road, V V Puram, Bangalore(2009-2010)

Ultrasonic techniques for hidden corrosion detection

BANGALORE INSTITUTE OF TECHNOLOGY

(K R Road, V V Puram, Bangalore)

Department of Mechanical Engineering (M-Tech)

CERTIFICATE

This is to certify that the seminar topic entitled “ULTRASONIC TECHNIQUES FOR

HIDDEN CORROSION DETECTION” is a bonafied work carried out by THEJAS N

bearing university seal number 1BI09MMD17 of 1st semester M.Tech in Machine Design at

Bangalore Institute of Technology, Bangalore in partial fulfillment of the Master of Technology

in Mechanical engineering (Machine Design) of Visveswaraiah Technological University,

Belgaum, during the year Sep2009-Jan2010. It is certified that all correction and deposited in

the department library. The seminar report has been approved as it satisfies the academic

requirement in respect of seminar work prescribed for the Master of Technology Degree.

PLACE :DATE : SIGNATURE OF STUDENT

SIGNATURE SIGNATURE SIGNATUREOF GUIDE OF H.O.D OF PRINCIPAL


ACKNOWLEGEMENTS

A great deal of time and effort has gone into successful execution of my seminar and

preparation of this seminar report. I would like to acknowledge the contribution from various

sources and people who have been instrumental in the success of this endeavor.

I wish to place on record my heart-felt thanks to Dr.M.Venkata Rama Reddy,

Professor and Head, Department of Mechanical Engineering, BIT for his ever inspiring support

and encouragement.

I sincerely express my gratitude to All Staff, Machine Design, and BIT for their kind

co-operation in guiding me in the seminar.

Thanks & Regards,

(THEJAS N)


CONTENTS

1. INTRODUCTION

2. HIDDEN CORROSION

3. TYPES OF CORROSION

3.1 Galvanic Corrosion

3.2 Pitting Corrosion

3.3 Erosion-Corrosion

3.4 Crevice Corrosion

3.5 Intergranular Corrosion

4. POTENTIAL DAMAGE AREAS OF CORROSION

5. ULTRASONIC TECHNIQUES

5.1 BASIC PRINCIPLE OF ULTRASONIC INSPECTION

5.2 MODES OF SOUND WAVE PROPAGATION

5.3 GUIDED ULTRASONIC WAVES FOR CORROSION DETECTION

CASE STUDY

6. CORROSION DETECTION IN AIRCRAFT STRUCTURES USING GUIDED LAMB WAVES

6.1 WHY GUIDED LAMB WAVES

6.2 OBJECTIVES

6.3 CONVENTIONAL ULTRASONIC INSPECTION

6.4 GUIDED WAVE INSPECTION

6.5 EXPERIMENTAL SETUP

7. APPLICATIONS OF ULTRASONIC TECHNIQUES

8. REFERENCES


1. INTRODUCTIONCorrosion is one of the serious problem affecting air force and other aviation industries.

It affects the aircraft on its wings, surface, between joints and fasteners. The presences of

corrosion underneath the paints of surface and between joints are not easy to be detected. The

unnoticed presence of corrosion may cause the aircraft to crash leading to human and money

loses. To detect the corrosion present on the metal surface, various methods and tests are used.

These tests conducted should be such that it does not destroy or disassemble the plane to parts

or damage its surface. Hence for the further use of the plane, Non-destructive tests (NDT) are

carried out.

Non-destructive testing as the name suggests is testing procedure without any damage to

the part being tested. The various non-destructive testing methods used are:

1) Visual inspection2) X-ray inspection3) Die (liquid) penetration inspection4) Magnetic particle inspection5) Eddy current inspection6) Ultrasonic inspection

Ultrasonic inspection is conventionally used for corrosion detection in aircraft wings. But the conventional inspection method carries with it certain defects like: (i) It scans perpendicular to the surface and hence rate of scanning (from point to point) is less and hence highly time consuming.(ii) Conventional method is not capable of detecting disbonds between layers and cracks at fastener holes.These defects are over come by a newly developed inspection method using guided ultrasonic waves.

Guided waves demonstrate an attractive solution where conventional ultrasonic

inspection techniques are less sensitive to defects such as corrosion/disbonds in thin

multilayered wing skin structures and hidden exfoliation under wing skin fasteners. Moreover,

with their multimode character, selection of guided wave modes can be optimized for detection

of particular types of defects. Mode optimization can be done by selecting modes with

maximum group velocities (minimum dispersion), or analysis of their wave mode structures

(particle displacements, stresses and power distributions). Guided Lamb modes have been used

for long range/large area corrosion detection and the evaluation of adhesively bonded

structures.

Ultrasonic guided waves are promising but require procedure development to ensure

high sensitivity and reliable transducer coupling and to provide a mechanism to transport the


probe(s) over the area to be scanned. This paper describes some practical inspection setups and

procedures based on guided wave modes for corrosion damage detection in single and

multilayered wing skin structures and exfoliation detection immediately adjacent to fasteners in

aircraft wing skin. It describes the results of their application to detection of corrosion in

simulated and real components of aircraft wing skin. Using a tone burst system, the wave

modes are selected, excited and tested in pulse echo and pitch catch setups. Launch angles were

obtained from the calculated dispersion curves. Theoretical group velocities were compared to

tested group velocities to confirm the excited modes at frequency thickness product and launch

angle. The simulated corrosion in single and multilayered wing skin structures and exfoliation

located under several rivets was successfully detected. Some guided Lamb modes proved to be

more sensitive to corrosion type defects and produced better results

2. HIDDEN CORROSIONHidden corrosion is a type of electro-chemical material degradation that is not readily or

directly detectable visually or by any other surface measurement technique. It can often be

detected and quantified in terms of reduction of wall thickness or structural discontinuities such

as pits, flaws and voids. When attempting to detect material degradation due to electro-

chemical processes, the corrosion products (e.g., iron oxides, aluminum oxides, etc.) must be

identified so that an appropriate energy source can be selected for detection.

3. TYPES OF CORROSION

Corrosion in aircraft may appear in various forms depending on the alloy, product form,

corrodent, general conditions and residual stress. This complicates the metrics of corrosion and

therefore also complicates the quantification of detection reliability. Some corrosion types are

listed below

3.1 Galvanic Corrosion

Galvanic corrosion is a very common form of corrosion that results from contact

between dissimilar metals. A difference in the electrode potential of the two metals and the

difference in the surface area of the dissimilar metals drive the process. Galvanic corrosion is

responsible for much of the corrosion in aircraft.

3.2 Pitting Corrosion


Pitting is another form of corrosion that results when the anodic site in the

electrochemical reaction corresponds to a local micro structural discontinuity, such as an

inclusion, grain boundary, or even a scratch, on an otherwise large cathodic surface area.

3.3 Erosion-Corrosion

Erosion-corrosion, as its name suggests, results from the actions of corrosion and

erosion in the presence of a moving corrosive fluid, causing accelerated loss of the metal.

3.4 Crevice Corrosion

Crevice corrosion is a form of localized corrosion that occurs near an area of a metal

surface adjacent to another metal that is sheltered from full exposure to the environment. The

reaction between the oxygen in the crevice and the rest of the metal causes a gradient in the

oxygen concentration, and thus a difference in electrode potentials and a flow of current.

3.5 Intergranular Corrosion

Intergranular corrosion occurs at or adjacent to the grain boundaries of a metal or alloy.

The actual mechanism of the corrosion varies with metal system. This attack at the grain

boundaries can cause entire metal grains to become dislodged. Leakage of corrosive fluids, loss

of effective cross sectional area, and mechanical failure can result.

4. POTENTIAL DAMAGE AREAS OF CORROSION The severity of corrosion attacks varies with aircraft type, design techniques, operating environments, operators and maintenance programs. Common areas of corrosion problems are listed below

1. Floor and structure in the vicinity of lavatory systems and galleries,

2. Structures surrounding doors, particularly landing gear doors,

3. wing skin adjacent to counter fastener heads,

4. Wing to body joint fittings,

5. Fuselage lower structure (bilge area),

6. Areas having environmentally unstable materials,

7. Structures susceptible to protective treatment damage during installation and repair, abrasion, fretting and erosion.

5. ULTRASONIC TECHNIQUES


5.1 BASIC PRINCIPLE OF ULTRASONIC INSPECTION

Fig1. Ultrasonic testing equipment

Ultrasonic Testing (UT) uses high frequency sound energy to conduct examinations and

make measurements. Ultrasonic inspection can be used for flaw detection/evaluation,

dimensional measurements, material characterization, and more.

A typical UT inspection system consists of several functional units, such as the

pulser/receiver, transducer, and display devices. A pulser/receiver is an electronic device that

can produce high voltage electrical pulses. Driven by the pulser, the transducer generates high

frequency ultrasonic energy. The sound energy is introduced and propagates through the

materials in the form of waves. When there is a discontinuity (such as a crack) in the wave path,

part of the energy will be reflected back from the flaw surface. The reflected wave signal is

transformed into an electrical signal by the transducer and is displayed on a screen.

5.2 MODES OF SOUND WAVE PROPAGATIONIn air, sound travels by the compression and rarefaction of air molecules in the direction

of travel. However, in solids, molecules can support vibrations in other directions, hence, a

number of different types of sound waves are possible. Waves can be characterized in space by

oscillatory patterns that are capable of maintaining their shape and propagating in a stable

manner. The propagation of waves is often described in terms of what are called “wave

modes.” The different types of modes of sound wave propagation in solids are listed below

5.2.1 Longitudinal waves and shear waves


Fig2. Longitudinal and shear wavesIn longitudinal waves, the oscillations occur in the longitudinal direction or the direction

of wave propagation. Since compressional and dilational forces are active in these waves, they

are also called pressure or compressional waves. They are also sometimes called density waves

because their particle density fluctuates as they move. Compression waves can be generated in

liquids, as well as solids because the energy travels through the atomic structure by a series of

compressions and expansion (rarefaction) movements.

In the transverse or shear wave, the particles oscillate at a right angle or transverse to the

direction of propagation. Shear waves require an acoustically solid material for effective

propagation, and therefore, are not effectively propagated in materials such as liquids or gasses.

Shear waves are relatively weak when compared to longitudinal waves. In fact, shear waves are

usually generated in materials using some of the energy from longitudinal waves.

5.2.2 Surface waves

Fig3. Surface waves

Surface (or Rayleigh) waves travel the surface of a relatively thick solid material

penetrating to a depth of one wavelength. Surface waves combine both a longitudinal and

transverse motion to create an elliptic orbit motion as shown in the image and animation below.

The major axis of the ellipse is perpendicular to the surface of the solid. As the depth of an


individual atom from the surface increases the width of its elliptical motion decreases. Surface

waves are generated when a longitudinal wave intersects a surface near the second critical angle

and they travel at a velocity between .87 and .95 of a shear wave. Rayleigh waves are useful

because they are very sensitive to surface defects (and other surface features) and they follow

the surface around curves. Because of this, Rayleigh waves can be used to inspect areas that

other waves might have difficulty reaching.

5.2.3 Plate waves (or lamb waves)

Fig4. Lamb wave

Plate waves are similar to surface waves except they can only be generated in materials

a few wavelengths thick. Lamb waves are the most commonly used plate waves in NDT.

Lamb waves are complex vibrational waves that propagate parallel to the test surface

throughout the thickness of the material. Propagation of Lamb waves depends on the density

and the elastic material properties of a component. They are also influenced a great deal by the

test frequency and material thickness. Lamb waves are generated at an incident angle in which

the parallel component of the velocity of the wave in the source is equal to the velocity of the

wave in the test material. Lamb waves will travel several meters in steel and so are useful to

scan plate, wire, and tubes. With Lamb waves, a number of modes of particle vibration are

possible, but the two most common are symmetrical and asymmetrical. The complex motion of

the particles is similar to the elliptical orbits for surface waves. Symmetrical Lamb waves

move in a symmetrical fashion about the median plane of the plate. This is sometimes called

the extensional mode because the wave is “stretching and compressing” the plate in the wave

motion direction. Wave motion in the symmetrical mode is most efficiently produced when the

exciting force is parallel to the plate. The asymmetrical Lamb wave mode is often called the

“flexural mode” because a large portion of the motion moves in a normal direction to the plate,


and a little motion occurs in the direction parallel to the plate. In this mode, the body of the

plate bends as the two surfaces move in the same direction.

5.3 GUIDED ULTRASONIC WAVES FOR CORROSION DETECTION

Guided ultrasonic wave NDE offers the potential for a cost effective methodology for

inspection of hidden corrosion in large and sometimes difficult to access areas, such as

insulated piping. The field of guided waves has reached some degree of maturity, but

unfortunately the number of practical applications compared to the number of research papers is

rather small. Guided waves can be used in three regimes, depending on inspection distance:

• Short range (<< 1 m)

• Medium range (up to about 5 m)

• Long range (up to around 100 m)

The short range methods include high frequency surface wave scanning with rayleigh

waves, leaky lamb waves, and acoustic microscopy in which a leaky surface wave is generated

by the lens. The medium range methods typically use frequencies in the 250 kHz to 1 MHz

range and are applicable to plate, tube and pipe testing. The long range method generally uses

long range frequencies below 100 kHz, and the primary advantage is that it allows a large area

to be tested from a single transducer location without tedious scanning. Long range testing,

which has the greatest potential utility in field-testing, is usually carried out in the pulse echo

mode

5.3.1 Basic principle of ultrasonic guided waves

Fig5. Basic principle of ultrasonic guided waves

The major difference between bulk wave propagation and guided wave propagation is

the fact that a boundary is required for guided wave propagation. As a result of a boundary

along a thin plate or interface, we can imagine a variety of different waves reflecting and mode

converting inside a structure and superimposing with areas of constructive and destructive


interference that finally leads to the nicely behaved guided wave packets that can travel in the

structure.

Fig5 shows the angle beam transducer for the generation of guided waves by pulsing a

piezoelectric element on the wedge placed on a test surface. As a result of refraction at the

interface between the wedge and the test specimen, a variety of different waves can propagate

in the structure and by way of mode conversion and reflection from the surfaces of the structure

can lead to interference patterns as a resulting wave vector propagates along the structure.

Snell’s law can be used to calculate the resulting phase velocity, sometimes referred to as a

‘‘Cremer hypothesis.’’ In doing calculations of finding out what interference packages might

come about in the material, one can produce a so-called ‘‘dispersion curve’’ that shows the

wave propagation possibilities of phase velocity and frequency that could possibly propagate in

the structure.

5.3.2 Air coupled ultrasonic guided wave for hidden corrosion detection in multilayer aircraft structures

Fig6.Air coupled ultrasonic guide waves

Non-contact air-coupled transducers can be used to apply guided waves to the

inspection of thinning in aluminum plates. In this application, a pair of micro machined gas

(air)-coupled capacitive transducers is used for the generation and detection of guided plate

modes. Features in the dispersive behavior of selected guided wave modes were used for the

detection of plate thinning. Mode cutoff measurements provided a qualitative detection of plate

thinning, while frequency shift measurements were able to provide a quantitative measure of

plate thinning. The experimental setup with air coupled transducers is shown in Figure6.Non-

contacting electromagnetic acoustic transducers (EMATs) can also be used to generate and

detect shear horizontal (SH)-guide waves for inspection and mapping of corrosion in pipe walls

and plates. The SH waves have a pure shear-motion parallel to the surfaces and perpendicular to


the plane of incidence. SH-guided waves have a unique feature in contrast to guided waves with

in plane polarization; the lowest order mode has no dispersion and the dispersion of the higher

order modes is much weaker than modes with polarization in the plane of incidence. As a result,

SH-guided waves could be economically and reliably used to detect and map corrosion in plates

and pipes. Couplant free excitation and the resultant simplified waveforms add to the versatility

and usefulness of the technique.

5.3.3 Advantages of guided ultrasonic waves Inspection over long distances from a single probe position.

By mode and frequency tuning, to establish wave resonances and excellent overall defect detection potential

Ability to detect structures under water, coatings, insulation, multilayer structures or concretes with an excellent sensitivity.

Potential with multimode and frequency lamb type, surface or horizontal shear waves to detect, locate, classify and size defects.

Cost effectiveness because of simplicity and speed

CASE STUDY

6. CORROSION DETECTION IN AIRCRAFT STRUCTURES USING GUIDED LAMB WAVES6.1 WHY GUIDED LAMB WAVES

Lamb wave are used because they offer an improved inspection potential due to their:

variable mode structure and distributions

multimode character

sensitivity to different type of flaws

propagation for long distances

Guiding character which enables them to follow curvature and reach hidden and/or

buried parts.

6.2 OBJECTIVES

Non-destructive testing methods for simple, rapid and reliable corrosion detection in

complex metallic assemblies is an on-going challenge; this is due to the size and

geometric complexity of these assemblies.


Nondestructive ultrasonic testing technique based on velocity change, attenuation and

backscattering is been successfully applied by using ultrasonic bulk waves. However,

plate waves whose velocity changes with frequency and thickness product can equally

be used to detect defects and corrosion in multilayered metallic structures.

This work demonstrates the benefits of Lamb waves for detecting corrosion in

aluminum multilayered structures.

The main objective therefore, was to develop NDT method, through a theoretical and

experimental work, to detect corrosion in multilayered aluminum structures.

Experimentally elaborated Guided wave testing method to determine quickly and

reliably where these multilayered structurally significant parts are in need of repair.

To demonstrate detectability and sensitivity of guided wave techniques, experiments

were performed on 1.0 -2.0 mm thick aluminum plates and facilitate interpretation

results are presented through imaging.

6.3 CONVENTIONAL ULTRASONIC INSPECTION

Fig7.Conventional ultrasonic inspection

With Conventional ultrasonic method like C-scan the area under interrogation at any

instant is limited to region covered by the transducer. Therefore, it is a localized point

by point inspection technique.

This method is an efficient conventional inspection technique but it is very time

consuming for large structural areas.

C-scans also have difficulty to inspect non uniform and buried structures, since with a

C-scan; a transducer needs access to each point of the inspected area.


6.4 GUIDED WAVE INSPECTION

Fig8. Lamb wave inspection technique

Lamb waves also known as plate waves are based on plate wave natural resonant

modes. Lamb waves are two dimensional stress waves are guided by the geometry of

the plate-like structures whose surfaces are free of stresses. They can propagate in plate-

like structures that are only a few wavelengths thick (d<=3l) where l represents the

incident wavelength.

Particle displacements and stresses in the Lamb waves occur throughout the thickness of

the plate. Their propagation properties depend on the density, the elastic properties and

geometrical structure of the inspected object and are also influenced by the thickness of

the material and the wave cyclic frequency.

6.5 EXPERIMENTAL SETUP


Fig9. Tone burst pulser/receiver system

The basic equipment in the instrumentation set up was a tone-burst pulser/receiver

system that can be used to excite a high power narrow-band width guided wave mode.

The schematic diagram of a generalized tone-burst system set up is given in the above

Figure.

The output of system is a tone-burst waveform which is fed to the sender (transmitting

transducer). This burst is initially formed of a continuous sine wave from the function

generator which is gated and subsequently amplified. The received signal (received

from the receiving transducer) is transferred to the broadband receiver through the

attenuator and the digital oscilloscope.

The flexibility of guided wave approach is based on mode selection, criteria which are

dictated by launch angle and excitation frequency.

The most widely employed method of guided wave excitation is the wedge or prismatic

coupling block method, which is based on conversion (Cook, Valkenburg and Minton

1954).


Dispersion curves describe the natural resonance of a specific structure. Commonly

presented as a plot of phase group velocity versus the frequency thickness of the

structure.

They depend upon material properties and the particular geometrical model selected.

We use the dispersion curves to determine the incidence angle of the transducer and to

select any desired mode.

Another type of dispersion curve is presented as a plot of group velocity versus

frequency*thickness product of the structure.

These graphs are essential for signal interpretation and identification

Detectability of corrosion was investigated in two aluminum specimens with two types of

simulated corrosion. The first specimen was an aluminum plate with dimension 460x405x1 mm

with controlled thinning in designated areas. This first type of corrosion is named open surface

corrosion because corrosion is visible to the naked eye. To demonstrate the sensibility of the

excited wave modes, corrosions were induced in three places with different level of thinning

(10%, 15% and 25%). Measurements were made using the pitch-catch setup which consists of

two variable angle broadband transducers with central frequencies at 3.5 MHz, one of the

transducers acts as transmitter used to generate the guided wave mode and the other one used to

receive the generated mode and its interaction with the corroded structure. The transducers are

driven by a tone-burst pulser/receiver system. The first set of tests demonstrates detectability of

the open corrosion on the aluminum plate using the pitch- catch setup with piezo-composite

transducers.

The inspection of bonded structure with pitch-catch setup is based on the following principles.

A guided Lamb wave mode once generated will travel from sender to receiver,

producing relatively high amplitude RF signal when a disbond exists between the two

bonded layers; otherwise it will leak in the tear strap if the bond is good, preventing the

generated wave mode from being received by the receiver.

Relative amplitude changes which occur in the transmitted wave mode through bonded

structures are an indication for the existence of disbond, corrosion or even missed tear

strap.


Thus,

The propagation of Lamb guided waves in plates and multilayered structures has been

presented.

The generation of pure modes and appropriate mode selection has been discussed.

Also demonstrated the tools to properly control, predict and launch guided waves in

aluminum.

Under different conditions, three sets of experimental tests utilizing So, S1 and A1

modes with different frequency-thickness product were performed.

Showed how the ultrasonic guided waves method can be used as a highly sensitive, fast

and cost effective inspection technique for disbond and corrosion detection.

Demonstrated that the ultrasonic guided wave method can be used as appropriate and

promising inspection technique.

Lamb wave inspection can detect disbond in lap splice joints and tear straps in a single

scan and the procedure is suitable for presentation of the results as an image.

7. APPLICATIONS OF ULTRASONIC TECHNIQUESSome of the applications of ultrasonic techniques for detecting hidden corrosion are as

follows

1. ULTRASONIC TECHNIQUE FOR THE DETECTION OF LINER CORROSION IN

A HB-53 HELICOPTER FUEL TANKS

Fig10. HB-53 fuel tank

2. ULTRASONIC TECHNIQUES FOR THE DETECTION OF DEFECTS IN RAILS

AND WELDED RAIL JOINTS


Fig11a. Shelling Fig11b.Flaking

Fig11. Surface defects

3. ULTRASONIC TECHNIQUES FOR RAPID ASSESSMENT OF CORROSION

DETECTION IN PIPING

Fig12.Electromagnetic acoustic transducer assembly on a pipe run4. ULTRASONIC TECHNIQUES FOR CORROSION DETECTION IN A STORAGE

TANKS

Fig13. Storage tank


8. REFERENCES “Corrosion Detection Technologies”, BDM Federal Inc., March 1998

L.E. Soley and J.L. Rose, “Ultrasonic Guided Waves for the Detection of Defects and

Corrosion in Multi-Layer Structures,” Review of Progress in Quantitative

Nondestructive Evaluation, Vol. 19B, 2000, pp. 1801-1808.

D. Tuzzeo and F. Lanza di Scalea, “Noncontact Air-Coupled Guided Wave Ultrasonic

for Detection of Thinning Defects in Aluminum Plates,” Research in Nondestructive

Evaluation, Vol. 13, No. 2, 2001, pp. 61-77

Y. Bar-Cohen, A.K. Mal and M. Lasser, “NDE of Hidden Flaws in Aging Aircraft

Structures Using Obliquely Backscattered Ultrasonic Signals (OBUS),” The SPIE

Conference on Nondestructive Evaluation of Aging Aircraft, Airports, and Aerospace

Hardware III, Vol. 3586, 1999, pp. 347-353.

J.C.I. Chang, “Aging Aircraft Science and Technology Issues and Challenges and USAF

Aging Aircraft Program”, Structural Integrity in Aging Aircraft, ASME: AD-Vol. 47,

1995.

“Corrosion Detection Technologies”, BDM Federal Inc., March 1998.

R.P. Dalton, P. Cawley and M.J.S. Lowe, “Propagation of Acoustic Emission Signals in

Metallic Fuselage Structure,” IEEE Proceedings: Science, Measurement and

Technology, Vol. 148, 2001a, pp. 169-177.

R.P. Dalton, P. Cawley and M.J.S. Lowe, “The Potential of Guided Waves for

Monitoring Large Areas of Metallic Aircraft Fuselage Structure,” Journal of NDE, Vol.

20, 2001b, pp. 29-46.

M.J. Quarry and J.L. Rose; “Multimode Guided Wave Inspection of Piping Using Comb

Transducers,” Materials Evaluation, Vol. 57, No. 10, October 1999, pp.1089-1090.

L.E. Soley and J.L. Rose, “Ultrasonic Guided Waves for the Detection of Defects and

Corrosion in Multi-Layer Structures,” Review of Progress in Quantitative

Nondestructive Evaluation, Vol. 19B, 2000, pp. 1801-1808.


D. Tuzzeo and F. Lanza di Scalea, “Noncontact Air-Coupled Guided Wave Ultrasonic

for Detection of Thinning Defects in Aluminum Plates,” Research in Nondestructive

Evaluation, Vol. 13, No. 2, 2001, pp. 61-77.

H.J. Salzburger, “Long Range Detection of Corrosion by Guided Shear Horizontal

(SH-) Waves,” The 7th European Conference on Non-Destructive Testing, Copenhagen,

May 1998, pp. 751-757.

F. Ravenscroft and C. Bull, “Corrosion Detection Using CHIME,” Insight, Vol. 42, No.

2, February 2000, pp. 80-83.

D.J. Barnard and D.K. Hsu, “Detection and Quantification of Intergranular Corrosion

Around Wing Skin Fasteners Using the Dripless Bubbler Ultrasonic Scanner,” Review

of Progress in Quantitative Nondestructive Evaluation, Vol. 18B, 1999, pp. 1821-1828.

P.S. Rutherford, “NDI Method to Locate Intergranular Corrosion Around Fastener

Holes in Aluminum Wing Skins,” SPIE, Vol. 3397, 1998, pp. 57-66.

M. Choquet, D. Levesque, M. Massabki, C. Neron, N.C. Bellinger, D. Forsyth, C.E.

Chapman, R. Gould, J.P. Komorowski and J.P. Monchain, “Laser-Ultrasonic Detection

of Hidden Corrosion in Aircraft Lap Joints: Results from Corroded Samples,” Review

of Progress in Quantitative Nondestructive Evaluation, Vol. 20B, 2001, pp. 300-307.

I.N. Komsky, “Ultrasonic Imaging of Hidden Defects Using Dry-coupled Ultrasonic

Probes,” Health Monitoring and Smart Nondestructive Evaluation of Structural and

Biological Systems V, edited by Tribikram Kundu, Proc. of SPIE, Vol. 61770M, 2006.

M. Lasser, B. Lasser, J. Kula and G. Rohrer, “Developments in Real-Time

2DUltrasound Inspection for Aging Aircraft,” SPIE Conference on Nondestructive

Evaluation of Aging Aircraft, Airports, and Aerospace Hardware III, Vol. 3586, 1999,

pp. 78-84.

Y. Bar-Cohen, A.K. Mal and M. Lasser, “NDE of Hidden Flaws in Aging Aircraft

Structures Using Obliquely Backscattered Ultrasonic Signals (OBUS),” The SPIE

Conference on Nondestructive Evaluation of Aging Aircraft, Airports, and Aerospace

Hardware III, Vol. 3586, 1999, pp. 347-353.

R. Rempt, “Scanning with Magnetoresistive Sensors for Subsurface Corrosion,” Review

of Quantitative Nondestructive Evaluation, Vol. 21B, 2002, pp. 1771-1778.


S. Giguere, B.A. Lepine and J.M.S. Dubois, “Pulsed Eddy Current Technology:

Characterizing Material Loss with Gap and Lift-off Variations,” Research in

Nondestructive Evaluation, Vol. 13, No.3, 2001, pp. 119-129.

M.S. Safizadeh, Z. Liu, C. Mandache, D.S. Forsyth and A. Fahr, “Automated Pulsed

Eddy Current Method for Detection and Classification of Hidden Corrosion,” Proc. Vth

International Workshop, Advances in Signal Processing for Non Destructive Evaluation

of Materials, Quebec City (Canada), 2-4 Aug. 2005, X. Maldague ed., E. du Cao, 2006,

pp. 75-84.

Y.S. Sun, T. Ouang and S. Upda, “Remote Field Eddy Current Testing: One of the

Potential Solutions for Detecting Deeply Embedded Discontinuities in Thick and

Multilayer Metallic Structures,” Materials Evaluation, Vol. 59, No. 5, May 2001, pp.

632-637.

D.K. Thome, “Development of an Improved Magneto-Optic/Eddy-CurrentImager,”

Published by The National Technical Information Service (NTIS), Springfield, Virginia,

April 1998.

L.D. Favro, R.L. Thomasand and X. Han, “State-of-the-Art of Thermal Wave Imaging

for NDE of Aging Aircraft,” Nondestructive Evaluation of Aging Aircraft, Airports, and

Aerospace Hardware III, SPIE Vol. 3586, March 1999, pp. 94-97.

X. Han, L.D. Favro, L. Li, Z, Ouyang, G. Sun, R.L. Thomas and D.M. Ahsbaugh,

“Quantitative Thermal Wave Corrosion Measurements on a DC-9 Belly Skin in the

Presence of Irregular Paint Thickness Variations,” Review of Progress in Quantitative

Nondestructive Evaluation, Vol. 20A, 2001, pp. 483-486.

N. Meyendorf, J. Hoffman and E. Shell, “Early Detection of Corrosion in Aircraft

Structures,” Review of Quantitative Nondestructive Evaluation, Vol. 21B, 2002, pp.

1792-1797.

W.P. Winfree and K.E. Cramer, “Reconstruction of Back Surface Profiles from Scanned

Thermal Line Source Data Using Neural Networks,” Review of Progress in Quantitative

Nondestructive Evaluation, Vol. 19A, 2000, pp. 691-698.

Rennell, R., "Results of Evaluation of NDI Equipment for Detection of Hidden

Corrosion on USAF Aircraft", Tinker AFB Reports prepared by ARINC Research

Corp., May 1993 and September 1995.

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