ndt of composite

8/3/2019 Ndt of Composite

1/24

A Seminar OnA Seminar OnRecent Advances in the NDT ofRecent Advances in the NDT of

Composite MaterialsComposite Materials

ByByBhavya KBhavya K

22ndnd Sem.,AME,M.Tech.Sem.,AME,M.Tech.NITK,SurathkalNITK,Surathkal


2/24

ContentsContents IntroductionIntroduction

Visual testingVisual testing Liquid penetrantsLiquid penetrants

RadiographyRadiography

High frequency ultrasonicsHigh frequency ultrasonics

Low frequency ultrasonicsLow frequency ultrasonics Fokker bond testerFokker bond tester

InfraInfra--red thermographyred thermography

HolographyHolography

Acoustic emissionAcoustic emission Other NDT techniquesOther NDT techniques

Emerging technologies and challengesEmerging technologies and challenges

ConclusionConclusion


3/24

IntroductionIntroduction

Greater specific strengthGreater specific strength Higher modulusHigher modulus

Better thermal propertiesBetter thermal properties


4/24

ApplicationsApplications


5/24

DefectsDefectsPly collation:

Foreign objectsPly misorientationsPly wrinkling

Curing:Porosity & voidsDelaminations

Matrix microcrackingAdhesive bonding:Adhesive unbonds

Foreign objectsCore defects

Machining & assembly:DelaminationsSurface nicks

Scratches

In-service:Delaminations

Moisture/temperaturedegradation


6/24

VT & LPTVT & LPT VT : Defects exposed to the surfaceVT : Defects exposed to the surface

Magnifying glassesMagnifying glasses

High intensity illuminatorsHigh intensity illuminators

Fibroscopes using optical fibresFibroscopes using optical fibres LPT : Discontinuities open to the surfaceLPT : Discontinuities open to the surface

Cracks,porosity & delaminations exposed to theCracks,porosity & delaminations exposed to theouter surface of FRP materialsouter surface of FRP materials--dye penetrant testsdye penetrant tests

Cheap & easyCheap & easy

Minimum amount of inspection timeMinimum amount of inspection time


7/24


8/24

RadiographyRadiography

Internal structure is seen byInternal structure is seen byexposing the sample to aexposing the sample to asource of penetrating radiationsource of penetrating radiation

& recording the shadow image& recording the shadow imageon a radiographic film placedon a radiographic film placedon the opposite sideon the opposite side

XX--rays & Gamma raysrays & Gamma rays

Relaxation of fibres,foreignRelaxation of fibres,foreigninclusions,delaminations,interninclusions,delaminations,intern

al cracks,voids etc.al cracks,voids etc. The thickness of FRP laminatesThe thickness of FRP laminates

& the exact no. of plies & their& the exact no. of plies & theirorientation can also beorientation can also bedetermineddetermined


9/24

RealReal--time Xtime X--rayray

Very fast,more accurate location & sizing ofVery fast,more accurate location & sizing ofthe defectsthe defects


10/24

Microfocus XMicrofocus X--rayray

Small source,Small source,greatgreatmagnificationmagnificationranging fromranging from3X to 1000X3X to 1000X


11/24

Computed tomographyComputed tomography

Computer processing of the distribution ofComputer processing of the distribution ofthe Xthe X--ray transmission coefficient in aray transmission coefficient in astructure using a series of viewing anglesstructure using a series of viewing angles

Resin content in FRP specimensResin content in FRP specimens

Gamma rays Backscatter techniqueGamma rays Backscatter technique--usesusesCompton Backscatter phenomenonCompton Backscatter phenomenon

Beta particles transmitted are counted andBeta particles transmitted are counted and

then the attenuation studiedthen the attenuation studied The difference in absorption coThe difference in absorption co--efficientsefficients

between the reinforcement and the resinbetween the reinforcement and the resinfor beta particlesfor beta particles


12/24

High Frequency UltrasonicsHigh Frequency Ultrasonics

High energy soundHigh energy soundwaveswaves

PiezoPiezo--electricelectrictransducerstransducers

CathodeCathode--ray tuberay tube

PulsePulse--echo & throughecho & throughtransmission methodstransmission methods

Disbands,voids &Disbands,voids &crackscracks

CharacterisationCharacterisationstudies of compositesstudies of composites


13/24

Low Frequency UltrasonicsLow Frequency Ultrasonics Ultrasonic frequencies of the order of 25KHzUltrasonic frequencies of the order of 25KHz

Probes are pointed in shapeProbes are pointed in shape

No liquid couplantNo liquid couplant

Phase & amplitude changesPhase & amplitude changes

Locating & measuring the extent of debondsLocating & measuring the extent of debonds

Fokker bond tester:Fokker bond tester: Bond strength within an accuracy of +5%Bond strength within an accuracy of +5%

Honeycomb sandwich CFRP productsHoneycomb sandwich CFRP products Variation in US resonance frequency due to theVariation in US resonance frequency due to the

effect of loading on the transducereffect of loading on the transducer


14/24

InfraInfra--red Thermographyred Thermography

Space applicationsSpace applicationsVery fast,& nonVery fast,& non--contactcontact

methodmethod

Large objects which areLarge objects which areinaccessibleinaccessible

Delamination,debonds,Delamination,debonds,

internal voidsinternal voids


15/24

HolographyHolography

Recording &Recording &reconstruction of anreconstruction of anoptical wavefrontoptical wavefront

Duplicates the originalDuplicates the original

wrt both amplitude &wrt both amplitude &phase distributionphase distribution

Stored in a sensitiveStored in a sensitive

photographic platephotographic plate(hologram)(hologram)

SubSub--surface defects insurface defects in

the FRP materialsthe FRP materials


16/24

Acoustic EmissionAcoustic Emission

Proof pressure testing of compositeProof pressure testing of compositepressure vessels used in spacepressure vessels used in space

applicationsapplications

Detects dynamic flawsDetects dynamic flaws

Can predict burst pressure to a high levelCan predict burst pressure to a high level

of accuracyof accuracy


17/24

Using EMATsUsing EMATs Requires no couplant,noncontactRequires no couplant,noncontact

Measurements can be done with high degree ofMeasurements can be done with high degree ofreproducibilityreproducibility

GraphiteGraphite--epoxy,glassepoxy,glass--epoxy,CMCepoxy,CMC Detection of mechanical anisotropy,skinDetection of mechanical anisotropy,skin--corecore

separation of a honeycomb sandwich structureseparation of a honeycomb sandwich structure


18/24

Laser shearographyLaser shearography

Disbond indication


19/24

Industrial applications of shearographyIndustrial applications of shearographyin inspection of aircraft componentsin inspection of aircraft components

Helicopterrotorblade inspection system View inside the vacuum chamber

withrotorblade in testing position

Autom

atic shea

rog

raphy syst

emfo

rab

radab

leseals inspection Portable shearography system for fieldinspection of compositematerials


20/24

Columbia accidentColumbia accident

high temperature degradation of carbonhigh temperature degradation of carbon--carbon compositescarbon composites

pinholes could have led to a weakening ofpinholes could have led to a weakening ofleading edge wing panels made of carbonleading edge wing panels made of carbon--carbon compositecarbon composite

the panels could have been susceptible tothe panels could have been susceptible todamage by foam debris that hit thedamage by foam debris that hit theshuttle's left wing after liftoff.shuttle's left wing after liftoff.


21/24

Other NDT TechniquesOther NDT Techniques

Microwave techniques,eddy currentMicrowave techniques,eddy currenttechniques,liquid crystals,nuclear magnetictechniques,liquid crystals,nuclear magnetic

resonance principles,dry & air coupledresonance principles,dry & air coupledultrasonics,cure monitoring usingultrasonics,cure monitoring usingdielectrometry & ultrasonics,ultrasonicdielectrometry & ultrasonics,ultrasonic

tomography,laser ultrasonics etc.tomography,laser ultrasonics etc.


22/24

Emerging Technologies &Emerging Technologies &

ChallengesChallenges Computer simulation models,neuralComputer simulation models,neural

networks,data fusion & inversion techniquesnetworks,data fusion & inversion techniques

Challenges:defect characterisationChallenges:defect characterisationmaterial property evaluationmaterial property evaluation

rapid scanning of large areasrapid scanning of large areas

smart structures applicationsmart structures applicationresidual stress measurementresidual stress measurement

weathering & corrosion damageweathering & corrosion damageassessmentassessment


23/24

ConclusionConclusion

Adoption of NDT technique depends on aAdoption of NDT technique depends on ano. of parameters like minimumno. of parameters like minimum

detectable flaw size & thickness of thedetectable flaw size & thickness of thepart,type & direction of flaw,instrumentpart,type & direction of flaw,instrumentavailability & ease of implementingavailability & ease of implementing

operationoperation Used in conjunction to bring out the mostUsed in conjunction to bring out the most

successful evaluation of a compositesuccessful evaluation of a composite

structurestructure


24/24

ReferencesReferences

By Thomas C. KoshyBy Thomas C. Koshy

www.laserwww.laser--ndt.co.uk/ images/laserndt.co.uk/ images/laser--shearography.jpgshearography.jpg

www.umaine.eduwww.umaine.edu

ndt of composite

Documents