IBEX 2003 Session 806 Hayden

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IBEX 2003IBEX 2003 -- Mami Beach FloridaMami Beach Florida

October 29, 2003October 29, 2003 11

NonNon--Destructive EvaluationDestructive Evaluation(NDE) for Surveyors(NDE) for Surveyors

William Hayden,William Hayden, PEPEViceVice--PresidentPresident--EngineeringEngineering

Davis and Company, Ltd.Davis and Company, Ltd.Fort Lauderdale, FloridaFort Lauderdale, Florida

Copyright 2003 Davis &Company, Ltd. - 800-223-8816

Session 806


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What do a l l NDEWhat do a l l NDETec hniques have inTec hniques have in

common?common?

They prov ide andThey prov ide and Ind ica t ionInd ica t ion of aof a

f law or im per fec t ion.f law or im per fec t ion.


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Met hods of NDTMet hods of NDT VisualVisual

AcousticAcoustic

ElectromagneticElectromagnetic

RadiographicRadiographic


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Visua l Inspec t ionVisual Inspec t ion

Visible SpectrumVisible Spectrum

Unaided eyesightUnaided eyesight

HandHand--held magnificationheld magnification

BoroscopeBoroscopeMicroscopeMicroscopeMacroMacro--LensLens

Infrared Spectrum (Thermography)Infrared Spectrum (Thermography)

Indicators (Dye Penetrant)Indicators (Dye Penetrant)


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ThermographyThermography

Theory of operationTheory of operation

Homogeneous materials transmit heat at a

constant rate.

Surface temperature gradients can bedetected with sensitive infrared detectors.


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Principle of operationPrinciple of operation

Discontinuities such as delaminations,

voids, or dry fibers slow the rate of heat

transfer within the material.

An infrared camera is used to detect thetemperature differences in radiated heat

within the structure.


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Common UsesCommon Uses

Detect Delaminations or voids in composites.Detect Delaminations or voids in composites. Detect overheating situations, such asDetect overheating situations, such as

Electrical circuits, breakers and motors.Electrical circuits, breakers and motors.

Shaft bearingsShaft bearings

Pump bearingsPump bearings


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NASA Langley Research Center Scanning Thermography System


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AdvantagesAdvantages

Sensor can be positioned at a distance awaySensor can be positioned at a distance awayfrom the test piece (nonfrom the test piece (non--contact).contact).

Digital output from sensor can be recorded forDigital output from sensor can be recorded for

later analysis.later analysis. Sensitivity on the order of 0.4 degree F.Sensitivity on the order of 0.4 degree F.

Large areas can be scanned in short time.Large areas can be scanned in short time.


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LimitationsLimitations

Process only highlights differences in thermalProcess only highlights differences in thermalconductivity of material.conductivity of material.

Inherent properties of composite materialsInherent properties of composite materials

manufacture may lead to false positive.manufacture may lead to false positive.

Need to confirm indications by other means.Need to confirm indications by other means.


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AcousticAcoustic




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Ultrasonic TestingUltrasonic Testing

Principle of operationPrinciple of operation beams of highbeams of high--frequency sound wavesfrequency sound waves

that are introduced into the materialthat are introduced into the materialbeing inspected to detect surface andbeing inspected to detect surface and

subsurface flaws.subsurface flaws. The sound waves travel through theThe sound waves travel through the

material and are reflected at interfaces.material and are reflected at interfaces.

The reflected beam is detected andThe reflected beam is detected andanalyzed to define the presence andanalyzed to define the presence andlocation of flaws.location of flaws.


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ProcedureProcedure

A sending transducer (probe or search unit)A sending transducer (probe or search unit)that emits a beam of ultrasonic waves whenthat emits a beam of ultrasonic waves when

bursts of alternating voltage are applied to it.bursts of alternating voltage are applied to it.

AA couplantcouplant to transfer energy in the beam ofto transfer energy in the beam ofultrasonic waves to the test piece.ultrasonic waves to the test piece.

A receiving transducer to accept and convertA receiving transducer to accept and convert

the output of ultrasonic waves from the testthe output of ultrasonic waves from the testpiece to corresponding bursts of alternatingpiece to corresponding bursts of alternating

voltage. In most systems, a single transducervoltage. In most systems, a single transducer

alternately acts as sender and receiver.alternately acts as sender and receiver.


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Common UsesCommon Uses

Thickness Gauging.Thickness Gauging. Internal Flaw detection.Internal Flaw detection.

Bond integrity in welded or brazed joints.Bond integrity in welded or brazed joints. soldering and adhesive bonding also can besoldering and adhesive bonding also can be

ultrasonically inspected.ultrasonically inspected.


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AdvantagesAdvantages Superior penetrating power for detectionSuperior penetrating power for detection

of deep flaws.of deep flaws.

High sensitivity, permits detection ofHigh sensitivity, permits detection of

small flaws.small flaws. Greater accuracy in finding position ofGreater accuracy in finding position of

flaws.flaws.

Only one surface need be accessible.Only one surface need be accessible.

Instantaneous indications of flaws.Instantaneous indications of flaws.


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Manual operation requiring trainedManual operation requiring trained

technician.technician. Some parts are difficult to inspect.Some parts are difficult to inspect.

Couplant between transducer and part.Couplant between transducer and part.

Reference standards neededReference standards needed

Manual recording of flaw locations.Manual recording of flaw locations.


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AcousticAcoustic




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Moisture MetersMoisture Meters


Resistance Meter

Uses two sharpprobes to measurethe resistancebetween the probes.

Capacitance Meter

Uses transmitter platesto send high frequencysignal through thematerial and senses the

attenuation of thesignal. Permittivity


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Resistance Meter

The resistance canvary depending theorientation of theprobes to the growth

rings in the wood.

Capacitance Meter

The attenuation of thesignal can be affectedby geometry of thelaminate including

thickness, internalstructure, or bottompaint.


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Moisture MeterMoisture Meter

AdvantagesAdvantages

Easy to use.Easy to use. Immediate results.Immediate results.

No specialized training necessaryNo specialized training necessary Compact sizeCompact size


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Moisture MeterMoisture Meter


False positives.False positives.

Readings affected by laminate properties.Readings affected by laminate properties.

No reference standard between models.No reference standard between models. Need to confirm results by taking coreNeed to confirm results by taking core

samples.samples.

Not computer recordable.Not computer recordable.

Manual recording of property locations.Manual recording of property locations.


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ConclusionsConclusions

Know the limitations of the equipmentKnow the limitations of the equipment

you use.you use. Remember, all NDE provides anRemember, all NDE provides an

indicationindication of a flaw or discontinuity.of a flaw or discontinuity. Appearances can be deceiving.Appearances can be deceiving.

To be absolutely sure, the part needsTo be absolutely sure, the part needsto be dissected.to be dissected.


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Questions?Questions?

Documents

IBEX 2003 Session 806 Hayden