UT _ Ultrasonic Testing

UT _ Ultrasonic Testing

1. MET312 NONMET312 NON--DESTRUCTIVE TESTING DESTRUCTIVE TESTING
MODULEMODULE--4 4 ––ULTRASONIC TESTINGULTRASONIC TESTING
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MODULEMODULE--4 4 ––ULTRASONIC TESTINGULTRASONIC TESTING
SukeshO P
Assistant Professor
Department of Mechanical Engineering,
JyothiEngineering College, Cheruthuruthy
9633103837 II [email protected]

2. ME357 Non-Destructive Testing
2
Introduction to NDTIntroduction to NDT--Visual InspectionVisual Inspection--Liquid Liquid
Penetrant InspectionPenetrant Inspection--Magnetic Magnetic Particle Particle
InspectionInspection--
Ultrasonic TestingUltrasonic Testing
--
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InspectionInspection--
Ultrasonic TestingUltrasonic Testing
--
Radiography TestingRadiography Testing--Eddy Current Testing.Eddy Current Testing.

3. Module-4 Syllabus
3

UltrasonicTesting:Basicprinciplesofsoundpropagation,
typesofsoundwaves,PrincipleofUT-methodsofUT,their
advantagesandlimitations-PiezoelectricMaterial,Various
typesoftransducers/probe-Calibrationmethods,contact
testingandimmersiontesting,normalbeamandstraight
beamtesting,anglebeamtesting,dualcrystalprobe,
ultrasonictestingtechniquesresonancetesting,through
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ultrasonictestingtechniquesresonancetesting,through
transmissiontechnique,pulseechotestingtechnique,
instrumentsusedUT,accessoriessuchastransducers,types,
frequencies,andsizescommonlyused.Referenceofstandard
blocks-techniquefornormalbeaminspection-flaw
characterizationtechnique,defectsinweldedproductsbyUT-
Thicknessdeterminationbyultrasonicmethod;-StudyofA,B
andCscanpresentations-TimeofFlightDiffraction(TOFD)

4. MODULEMODULE--44
4
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6. 6

The three types of sound are:

InfrasonicInfrasonic::Itisasoundwithafrequencyoflessthan
20Hz.ElephantsuseInfrasonicsoundstointeract
withherdshundredsofkmaway.
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withherdshundredsofkmaway.

SonicSonic::Itisasoundwiththefrequencybetween20
to20,000Hz....

UltrasonicUltrasonic::Itisasoundwithafrequencymorethan
20,000Hz.

7. Infrasonic sound
7

Havingorrelatingtoafrequencybelowthe
audibilityrangeofthehumanear.

utilizingorproducedbyinfrasonicwavesor
vibrations.
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vibrations.

Infrasound,isalow-frequencysoundlessthan
20Hz.Animalsthatcancommunicateusinginfrasonic
soundsare;Rhinos,hippos,elephants,whales,
octopus,pigeons,squid,cuttlefish,cod,Guinea
fowl.

8. Ultrasonic sound
8

Thedefinitionofultrasonic,alsoknownas
ultrasound,issoundwavesthathaveahigher
frequencythanthehumanearcanhear .An
exampleofultrasonicisanultrasoundimageofan
unbornbaby.
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unbornbaby.

Bats,Insectslikebeetles,moths,prayingmantis,
dolphins,dogs,frogsandtoads,etc.communicate
usingultrasonichearing.

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11. INTRODUCTION INTRODUCTION
11

Ultrasonictesting(UT)whichisapplicabletomost
materials,metallicornon-metallic.

Ultrasonictestinguseshighfrequencysoundenergyto
conductexaminationsandmakemeasurements.

Ultrasonicexaminationscanbeconductedonawide
Frequencies from 1-10 Mega Hertz(MHz)
are typically used.
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
Ultrasonicexaminationscanbeconductedonawide
varietyofmaterialformsincludingcastings,forgings,
welds,andcomposites.

Bythismethod,surfaceandinternaldiscontinuitiessuch
aslaps,seams,voids,cracks,blowholes,inclusionsand
lackofbondcanbeaccuratelyevaluatedfromone
side.

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17. Basic Principle of UT
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
Inultrasonictesting,ultrasoundtransducerconnectedto
adiagnosticmachineispassedovertheobjectbeing
inspected.

Thetransduceristypicallyseparatedfromthetest
objectbyacouplant(suchasoil)orbywater,asin
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objectbyacouplant(suchasoil)orbywater,asin
immersiontesting.However,whenultrasonictestingis
conductedwithanElectromagneticAcousticTransducer
(EMAT)theuseofcouplantisnotrequired.

Therearetwomethodsofreceivingtheultrasound
waveform:reflectionandattenuation

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19. SOUND
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Wavelength :

The distance required to complete a cycle
–Measured in Meter or mm
Frequency :
The number of cycles per unit time
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
The number of cycles per unit time
–Measured in Hertz (Hz) or Cycles per second (cps)
Velocity :

How quick the sound travels

Distance per unit time
–Measured in meter / second (m / sec)

20. Basic Principles of Sound

Sound is produced by a vibrating body and travels in the form
of a wave.

Sound waves travel through materials by vibrating the
particles that make up the material.

The pitch of the sound
is determined by the is determined by the
frequency of the wave
(vibrations or cycles
completed in a certain
period of time).

Ultrasound is sound
with a pitch too high
to be detected by the
human ear.
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21. Properties of a sound wave
21

Sound cannot travel in vacuum

Sound energy to be transmitted / transferred from
one particle to another
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22. Sound waves
22

All sound waves, whether audible or ultrasonic, are
mechanical vibrations involving movement of the
medium in which they are travelling.

A sound wave may be transmitted through any
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
A sound wave may be transmitted through any
material which behaves in an elastic manner.

Longitudinal waves

Transverse or shear waves

Surface or Rayleigh waves

23. Ultrasonic waves

Ultrasonic waves are very similar to light waves
in that they can be reflected, refracted, and
focused.

Reflection and refraction occurs when sound
waves interact with interfaces of differing
acoustic properties.

In solid materials, the vibrational energy can be
split into different wave modes when the wave
encounters an interface at an angle other than
90 degrees.

Ultrasonic reflections from the presence of
discontinuities or geometric features enables
detection and location.

The velocity of sound in a given material is
constant and can only be altered by a change in
the mode of energy.
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24. Longitudinal waves
24

Longitudinalwavesarewavesinwhichthe
displacementofthemediumisinthesamedirection
as,ortheoppositedirectionto,thedirectionof
propagationofthewave.
Mechanicallongitudinalwavesarealso
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
Mechanicallongitudinalwavesarealso
calledcompressionalorcompressionwaves,because
theyproducecompressionandrarefactionwhen
travelingthroughamedium,andpressurewaves,
becausetheyproduceincreasesanddecreasesin
pressure.

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26. Transverse or shear wave
26

Atransverse waveis a moving wave that consists of
oscillations occurring perpendicular (right angled) to the
direction of energy transfer (or the propagation of the
wave).
If a transverse wave is moving in the positivex-
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
If a transverse wave is moving in the positivex-
direction, its oscillations are in up and down directions
that lie in they–zplane.

Lightis an example of a transverse wave, while soundis
alongitudinal wave. A ripple in a pond and a wave on
a string are easily visualized as transverse waves.

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28. Surface or Rayleigh waves
28

Thistypeofwavescantravelonlyalongsurface
boundedononesidebystrongelasticforcesofthe
solidandontheotherbynearlynonexistentelastic
forcesbetweengasmolecules.
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
Surfacewavesthereforeareessentiallynonexistent
inasolidimmersedinliquid,unlesstheliquidcovers
thesolidsurfaceonlyasaverythinlayer.

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30. Plate or Lamp waves
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33. VELOCITY
33

ThevelocityofsoundinaparticularmaterialisCONSTANT

ItistheproductofDENSITYandELASTICITYofthematerial

ItwillNOTchangeiffrequencychanges

Onlythewavelengthchanges

Examples:
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
Examples:

VCompressioninsteel:5960m/s

VCompressioninwater:1470m/s

VCompressioninair:330m/s

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38. FREQUENCY
38

Generallythechoiceoftestfrequencydepends
upontwofactors:thetheminimumminimumsizesizeofofdefect,defect,whichwhich
isistotobebedetecteddetectedandandthethemediummediumininwhichwhichsuchsuchaa
defectdefectisissituatedsituated..
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42. Reflection
42

Lightcanbendandmovethroughthematerial,
whichiscalledrefraction.Or,lightcanbounceoff
thematerial,whichiscalledreflection.

Whensoundtravelsinagivenmedium,itstrikesthe
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
Whensoundtravelsinagivenmedium,itstrikesthe
surfaceofanothermediumandbouncesbackin
someotherdirection,thisphenomenon
iscalledthereflectionofsound.Thewaves
arecalledtheincidentandreflectedsoundwaves.

43. Divergence
43

Atermusedtodescribethespreadingofultrasonic
wavesbeyondthenearfield.Itisafunctionofthe
transducerdiameterandwavelengthinthe
medium.
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
Divergenceangle,anglewithinthefarfieldbetween
thebeamaxisandthebeamedge atwhichthe
amplitudehasfallenbyadefinedlevel

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
Scattering:itisthereflectionofsoundbeamfrom
itsoriginaldirectionofpropagation.

Absorption:itisconversionofsoundenergyfrom
oneformtosomeanotherform.
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oneformtosomeanotherform.

45. Attenuation of sound waves
45

Itisacombinedeffectofscatteringandabsorption.
Whichstatesthatwhenasoundbeamtravels
throughanymedium,itsintensitygraduallyreduces
duetoscatteringandabsorption.
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
Attenautiondefinesthedecayrateofpropagated
soundwave.

46. TEST TECHNIQUESTEST TECHNIQUES
46

Ultrasonictestingisaveryversatileinspectionmethod,and
inspectionscanbeaccomplishedinanumberofdifferentways.

Ultrasonicinspectiontechniquesarecommonlydividedintothree
primaryclassifications.
Pulse-echoandThroughTransmission
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
Pulse-echoandThroughTransmission
-(Relatestowhetherreflectedortransmittedenergyisused)

NormalBeamandAngleBeam
-(Relatestotheanglethatthesoundenergyentersthetestarticle)

ContactandImmersion
-(Relatestothemethodofcouplingthetransducertothetestarticle)

47. Pulse Pulse Echo Echo MethodMethod
47

Thisisthemethodmostcommonlyutilizedinthe
ultrasonictestingofmaterials.Thetransmitterand
receiverprobesareonthesamesideofthespecimen
andthepresenceofadefectisindicatedbythe
receptionofanechobeforethatofthebackwallecho.
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receptionofanechobeforethatofthebackwallecho.

The CRT screen is calibrated to show the separation in
distance between the time of arrival of a defect echo
as against that of the back wall echo of the specimen,
therefore, the location of a defect can be assessed
accurately.

48. Pulse Echo Technique
48
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49. Pulse Echo Technique
49

Single probe sends and receives sound

Gives an indication of defect depth and dimensions

Not fail safe
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50. Through Transmission MethodThrough Transmission Method
50

In this method two ultrasonic probes are used.

One is the transmitter probe and the other is the
receiver probe.
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
In this method the presence of an internal defect is
indicated by a reduction in signal amplitude, or in
the case of gross defects, complete loss of the
transmitted signal.
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52. Through transmission testing
Through transmission signal
1
1
T R
52
0246810
2
2
T R
Flaw
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53. Through Transmission Technique
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54. Through Transmission Technique
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
Advantages

Less attenuation

No probe ringing

No dead zone

Orientation does not matter
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Orientation does not matter

Disadvantages

Defect not located

Defect can’t be identified

Vertical defects don’t show

Must be automated

Need access to both surfaces

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56. Resonance MethodResonance Method
56

Aconditionofresonanceexistswheneverthe
thicknessofamaterialequalshalfthewavelength
ofsoundoranymultiplethereofinthatmaterial.

Controlofwavelengthinultrasonicsisachievedby
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
Controlofwavelengthinultrasonicsisachievedby
controloffrequency.

57. Resonance Method
57

Knowingtheresonanceorfundamentalfrequencyf
andvelocityVofultrasoundinthespecimenthe
thickness‘t’ofthespecimenundertestcanbe
calculatedfromtheequation:-
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
Sinceitisdifficulttorecognizethefundamental
modeofvibration,thefundamentalfrequencyis
usuallycalculatedfromthedifferenceoftwo
adjacentharmonicswhicharedepictedbytwo
adjacentrisesinthepulseamplitude.

58. Resonance Method
58

Thismethodisusedfortheinspectionoflargeingots
andcastingsparticularlywhentheattenuationis
highandgrossdefectsarepresent.

Themethoddoesdoesnotnotgivegivethethesizesizeandandlocationlocationofof
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
Themethoddoesdoesnotnotgivegivethethesizesizeandandlocationlocationofof
thethedefectdefect..Inadditiongoodmechanicalcoupling
andalignmentofthetwoprobesisessential.

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
Techniquesofultrasonictestingareeitherofthe
contacttypeortheimmersiontype.

InInthethecontactcontacttypetype,theprobeisplacedindirect
contactwiththetestspecimenwithathinliquidfilm
usedasacouplantforbettertransmissionof
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usedasacouplantforbettertransmissionof
ultrasonicwavesintothetestspecimen.

InInthetheimmersionimmersiontypetype,awaterproofprobeisused
atsomedistancefromthetestspecimenandthe
ultrasonicbeamistransmittedintothematerial
throughawaterpathorwatercolumn.

60. Contact Type Techniques
60
NormalNormalBeamBeamTechniquesTechniques::

Inthenormalbeamtechniquetheultrasonicbeamis
projectedperpendicularlyintothetestspecimen.This
techniquemayuseeithersingle,doubleorSEnormal
beamprobes.
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beamprobes.

Withthesingleprobe,thetransduceroftheprobeacts
asbothtransmitterandreceiver.

Inthistechniqueanultrasonicbeampulseisprojected
atintothespecimenandechoesfromtheflawswithin
thespecimenandfromthebackwallofthespecimen
arereceived.

61. Straight beam inspection techniques:
Direct contact,
single element probe
Direct contact,
dual element probe
Fixed delay
61
Immersion testingThrough transmission
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
AngleAngleBeamBeamTechniquesTechniques

Theanglebeamtechniqueisusedtotransmitultrasonic
wavesintoatestspecimenatapredeterminedpredeterminedangleangle
totothethetesttestsurfacesurface..

Accordingtotheangleselected,thewavemodes
producedinthetestspecimenmaybemixed
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
Accordingtotheangleselected,thewavemodes
producedinthetestspecimenmaybemixed
longitudinalandtransverse,transverseonly,orsurface
wavemodes.

TransverseTransversewaveswavesatvariousanglesofrefraction
between3535°°andand8080°°areusedtolocatedefectswhose
orientationisnotsuitablefordetectionbynormalbeam
techniques.

63. 63
SurfaceSurfaceWaveWaveTechniquesTechniques

Surfacewavetechniqueshavebeenusedverysuccessfully
foragreatnumberofapplications,particularlyinthe
AircraftIndustry.

Themainadvantageofsurfacewavesisthattheyfollow
gentlecontoursandarereflectedsharplyonlybysudden
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gentlecontoursandarereflectedsharplyonlybysudden
changesincontour,thusmakingitaveryusefultoolforthe
examinationofcomplexshapedcomponents.

Themainlimitationofthesewavesisthattheyarealmost
immediatelyattenuatedifthesurfacefinishisrough,is
coveredinscaleoraliquid(suchasthecouplant),orifany
pressureisappliedbyanotherobject(suchasthehandof
theoperator).

64. Immersion Testing Techniques
64

Immersiontestingtechniquesaremainlyusedinthe
laboratorylaboratoryandandforforlargelargeinstallationsinstallationsdoingdoingautomaticautomatic
ultrasonicultrasonictestingtesting..Ithastheadvantagethatuniform
couplantconditionsareobtainedandlongitudinaland
transversewavescanbegeneratedwiththesame
probesimplybychangingtheincidentbeamangle.
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probesimplybychangingtheincidentbeamangle.

Intheimmersiontechniqueboththeprobeandthetest
specimenareimmersedinwater.Theultrasonicbeamis
directedthroughthewaterintothetestspecimen,using
eitheranormalbeamtechniqueforgenerating
longitudinalwavesorananglebeamtechniquefor
generatingtransversewaves.

65. surface =
sound entry
backwall flaw
1 2
water delay
Immersion testing
65
0246810 0246810
IE IE
IP IP
BE BE
F
1 2
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67. Immersion testing
67

Inthebubblerorsquirtertechnique,theultrasonicbeam
isdirectedthroughawatercolumnintothetest
specimen.

ThisThistechniquetechniqueisisusuallyusuallyusedusedwithwithananautomatedautomatedsystemsystem
forforhighhighspeedspeedscanningscanningofofplate,plate,sheet,sheet,stripstrip,,cylindricalcylindrical
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forforhighhighspeedspeedscanningscanningofofplate,plate,sheet,sheet,stripstrip,,cylindricalcylindrical
formsformsandandotherotherregularlyregularlyshapedshapedformsforms..

Theultrasonicbeamiseitherdirectedina
perpendiculardirection(i.e.normaldirection)tothe
testspecimentoproducelongitudinalwavesoris
adjustedatanangletothesurfaceofthetestspecimen
fortheproductionoftransversewaves.

68. Immersion testing
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69. Immersion testing
69

Inthewheeltransducertechniquetheultrasonic
beamisprojectedthroughawater-filledtireinto
thetestspecimen.

Theprobe,mountedonthewheelaxle,isheldina
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
Theprobe,mountedonthewheelaxle,isheldina
fixedpositionwhilethewheelandtirerotatefreely.

Thewheelmaybemountedonamobileapparatus
thatrunsacrossthespecimen,oritmaybemounted
onastationaryfixture,wherethespecimenis
movedpastit

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71. EquipmentEquipment
Equipment for ultrasonic testing is very diversified.
Proper selection is important to insure accurate
inspection data as desired for specific applications.
In general, there are three basic components that
comprise an ultrasonic test system:
71
comprise an ultrasonic test system:
-Instrumentation
-Transducers
-Calibration Standards
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72. 1. TRANSDUCERS
•Transducers are manufactured in a variety of forms,
shapes and sizes for varying applications.
•Transducers are categorized in a number of ways which
include:
-Contact or immersion
72
-Contact or immersion
-Single or dual element
-Normal or angle beam
•In selecting a transducer
for a given application, it
is important to choose the
desired frequency,
bandwidth, size, and in some cases focusing
which optimizes the inspection capabilities.
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73. Contact Transducers
Contacttransducersare
designedtowithstand
rigoroususe,andusuallyhave
awearplateonthebottom
surfacetoprotectthe
piezoelectricelementfrom
contactwiththesurfaceofthe
piezoelectricelementfrom
contactwiththesurfaceofthe
testarticle.
Manyincorporateergonomic
designsforeaseofgripwhile
scanningalongthesurface.
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74. Contact Transducers (cont.)

Contacttransducersareavailablewith
twopiezoelectriccrystalsinone
housing.Thesetransducersarecalled
dualelementtransducers.

Onecrystalactsasatransmitter,the
otherasareceiver.

Thisarrangementimprovesnearsurface
resolutionbecausethesecond
transducerdoesnotneedtocompletea
transmitfunctionbeforelisteningfor
echoes.

Dualelementsarecommonlyemployed
inthicknessgaugingofthinmaterials.
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75. Contact Transducers (cont.)

Awaytoimprovenearsurface
resolutionwithasingleelement
transduceristhroughtheuseofadelay
line.

Delaylinetransducershaveaplastic
piecethatisasoundpaththatprovides
atimedelaybetweenthesound
generationandreceptionofreflectedgenerationandreceptionofreflected
energy.

Interchangeablepiecesmakeit
possibletoconfigurethetransducer
withinsulatingwearcapsorflexible
membranesthatconformtorough
surfaces.

Commonapplicationsincludethickness
gaugingandhightemperature
measurements.
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76. Angle beam Transducers

Anglebeamtransducers
incorporatewedgestointroduce
arefractedshearwaveintoa
material.

Theincidentwedgeangleisused
withthematerialvelocityto
determinethedesiredrefracteddeterminethedesiredrefracted
shearwaveaccordingtoSnell’s
Law)

Transducerscanusefixedor
variablewedgeangles.

Commonapplicationisinweld
examination.
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77. Immersion Transducers

Immersiontransducersare
designedtotransmitsound
wherebythetransducerandtest
specimenareimmersedinaliquid
couplingmedium(usuallywater).

Immersiontransducersare
manufacturedwith planar,
cylindricalorsphericalacoustic
lenses(focusinglens).
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80. 2. INSTRUMENTATION

Ultrasonicequipmentisusuallypurchasedtosatisfy
specificinspectionneeds,someusersmaypurchase
generalpurposeequipmenttofulfillanumberof
inspectionapplications.

Testequipmentcanbeclassifiedinanumberof
80

Testequipmentcanbeclassifiedinanumberof
differentways,thismayincludeportableorstationary,
contactorimmersion,manualorautomated.

Furtherclassificationofinstrumentscommonlydivides
themintofourgeneralcategories:D-meters,Flaw
detectors,Industrialandspecialapplication.
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81. D-meters or digital thickness gauge

D-meters or digital thickness
gauge instruments provide
the user with a digital
(numeric) readout.

They are designed primarily
for corrosion/erosion for corrosion/erosion
inspection applications.
•Someinstrumentsprovidetheuserwithbothadigital
readoutandadisplayofthesignal.Adistinctadvantage
oftheseunitsisthattheyallowtheusertoevaluatethe
signaltoensurethatthedigitalmeasurementsareofthe
desiredfeatures.
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APME/JECC
81

82. Flaw detectors

Flawdetectorsareinstruments
designedprimarilyforthe
inspectionofcomponentsfor
defects.

However,thesignalcanbe
evaluatedtoobtainother
informationsuchasmaterialinformationsuchasmaterial
thicknessvalues.

Bothanaloganddigitaldisplay.

Offertheuseroptionsofgating
horizontalsweepandamplitude
threshold.
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APME/JECC
82

83. Industrial flaw detection instruments

Industrialflawdetection
instruments,provideuserswith
moreoptionsthanstandard
flawdetectors.

Maybemodulatedunits
allowinguserstotailortheallowinguserstotailorthe
instrumentfortheirspecific
needs.

Generallynotasportableas
standardflawdetectors.
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APME/JECC
83

84. Immersion ultrasonic scanning systems

Immersionultrasonicscanningsystems
areusedforautomateddata
acquisitionandimaging.

Theyintegrateanimmersiontank,
ultrasonicinstrumentation,ascanning
bridge,andcomputercontrols.

Thesignalstrengthand/orthetime-

Thesignalstrengthand/orthetime-
of-flightofthesignalismeasuredfor
everypointinthescanplan.

Thevalueofthedataisplottedusing
colorsorshadesofgraytoproduce
detailedimagesofthesurfaceor
internalfeaturesofacomponent.
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APME/JECC
84

85. Images of a Quarter Produced With an Ultrasonic
Immersion Scanning System
85
Gray scale image produced using
the sound reflected from the front
surface of the coin
Gray scale image produced using the
sound reflected from the back surface
of the coin
(inspected from “heads” side)
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86. 3. CALIBRATION STANDARDS

Calibrationisaoperationofconfiguringtheultrasonictest
equipmenttoknownvalues.Thisprovidestheinspectorwith
ameansofcomparingtestsignalstoknownmeasurements.

Calibrationstandardscomeinawidevarietyofmaterial
types,andconfigurationsduetothediversityofinspection
86
types,andconfigurationsduetothediversityofinspection
applications.

Calibrationstandardsaretypicallymanufacturedfrom
materialsofthesameacousticpropertiesasthoseofthe
testarticles.
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87. Calibration Standards (cont.)
Thickness calibration
standards may be flat or
curved for pipe and tubing
applications, consisting of
simple variations in material
thickness.
ASTM Distance/Area Amplitude
87
thickness.
Distance/Area Amplitude
standards utilize flat bottom
holes or side drilled holes to
establish known reflector size
with changes in sound path
form the entry surface.
NAVSHIPS
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88. Calibration Standards (cont.)
There are also calibration
standards for use in angle
beam inspections when
flaws are not parallel to
entry surface.
IIW
DSC DC Rhompas
88
These standards utilized
side drilled holes, notches,
and geometric
configuration to establish
time distance and
amplitude relationships.
SC
ASME Pipe Sec. XI
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89. Qualification Standards
Qualification standards
differ from calibration
standards in that their
use is for purposes of
varying proper
equipment operation
AWS Resolution
DC-dB Accuracy
89
equipment operation
and qualification of
equipment use for
specific codes and
standards.
IOW Beam Profile
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90. 90
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91. 91
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92. DATA PRESENTATION

Information from ultrasonic testing can be presented in a
number of differing formats.

Three of the more common formats include:

A-scan
B-scan
92

B-scan

C-scan
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93. Data Presentation -A-scan

AA--scan presentation displays scan presentation displays
the amount of received the amount of received
ultrasonic energy as a function ultrasonic energy as a function
of time.of time.

Relative discontinuity size can
be estimated by comparing
Signal Amplitude
be estimated by comparing
the signal amplitude to that
from a known reflector.

Reflector depth can be
determined by the position of
the signal on the horizontal
sweep.
Time
Signal Amplitude
Time
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APME/JECC
93

94. Data Presentation -B-scan

BB--scan presentations display a scan presentations display a
profile view (crossprofile view (cross--sectional) sectional)
of a test specimen.of a test specimen.

Only the reflector depth in the
cross-section and the linear
94
cross-section and the linear
dimensions can be
determined.

A limitation to this display
technique is that reflectors
may be masked by larger
reflectors near the surface.
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95. Data Presentation -C-scan

The CThe C--scan presentation displays a plan type view of the test scan presentation displays a plan type view of the test
specimen and discontinuities.specimen and discontinuities.

C-scan presentations are produced with an automated data
acquisition system, such as in immersion scanning.

Use of A-scan in conjunction with C-scan is necessary when
depth determination is desired.
95
depth determination is desired.
Photo of a Composite
Component
C-Scan Image of
Internal Features
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96. ADVANTAGE OF ULTRASONIC TESTING

Sensitive to small discontinuities both surface and subsurface.

Depth of penetration for flaw detection or measurement is superior
to other methods.

Only single-sided access is needed when pulse-echo technique is
used.
96
used.

High accuracy in determining reflector position and estimating size
and shape.

Minimal part preparation required.

Electronic equipment provides instantaneous results.

Detailed images can be produced with automated systems.

Has other uses such as thickness measurements, in addition to flaw
detection.
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97. LIMITATIONS OF ULTRASONIC TESTING

Surface must be accessible to transmit ultrasound.

Skill and training is more extensive than with some other methods.

Normally requires a coupling medium to promote transfer of sound
energy into test specimen.

Materials that are rough, irregular in shape, very small,
exceptionally thin or not homogeneous are difficult to inspect.
97

Materials that are rough, irregular in shape, very small,
exceptionally thin or not homogeneous are difficult to inspect.

Cast iron and other coarse grained materials are difficult to inspect
due to low sound transmission and high signal noise.

Linear defects oriented parallel to the sound beam may go
undetected.

Reference standards are required for both equipment calibration,
and characterization of flaws.
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98. Block diagram: Ultrasonic Instrument
amplifier
horizontal
IP
screen
98
work piece
probe
sweep
clock
pulser
BE
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99. Sound reflection at a flaw
Probe
s
99Probe
Flaw
Sound travel path
Work piece
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100. Plate testing
IP
F
BE
100
delamination
plate
0 246810
F
IP = Initial pulse
F = Flaw
BE = Backwall echo
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101. s
Wall thickness measurement
101
0246810
s
s
Corrosion
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102. Weld inspection
020406080100
a = s sinß
a' = a -x
d' = s cosß
s
F
ß = probe angle
s = sound path
a = surface distance
a‘ = reduced surface distance
d‘= virtual depth
102
020406080100
s
a
a'
d
x
d = 2T -t'
Lack of fusion
Work piece with welding
d‘= virtual depth
d = actual depth
T= material thickness
ß
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103. MODULEMODULE--44
103

UltrasonicTesting(UT):principle,typesofwaves,frequency,
velocity,wavelength,reflection,divergence,attenuation,mode
conversioninultrasonicUTtestingmethodscontacttestingand
immersiontesting,normalbeamandstraightbeamtesting,
anglebeamtesting,dualcrystalprobe,ultrasonictesting
Compiled by : SUKESH O P/ APME/JECC
anglebeamtesting,dualcrystalprobe,ultrasonictesting
techniquesresonancetesting,throughtransmissiontechnique,
pulseechotestingtechnique,instrumentsusedUT,accessories
suchastransducers,types,frequencies,andsizescommonly
usedReferenceblockswithartificiallycreateddefects,
calibrationofequipment,Applications,advantages,limitations,
A,BandCscan-TimeofFlightDiffraction(TOFD).

104. Assignment 2.1
104
Write short notes on dual crystal probe and
Time of Flight Diffraction (TOFD).
Describe Piezo electric effect and piezo electric
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
Describe Piezo electric effect and piezo electric
transducers electro magnetic acoustic transducer