ASNT Spring 2006-Final

8/9/2019 ASNT Spring 2006-Final

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Comparison of Reflection ModeComparison of Reflection Mode

Acoustography and CAcoustography and C--scan Ultrasonicscan UltrasonicTechniques for the Single SidedTechniques for the Single Sided

Inspection of Aerospace MaterialsInspection of Aerospace Materials

R.E. Martin

Cleveland State University/NASA GRC

A. Mandlik, W. Popek, M. Sonpatki, J. Sandhu

Santec Systems Inc.D. Roth

NASA Glenn Research Center

C. Pergantis

US Army Research Laboratory


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OutlineOutline

IntroductionIntroduction

Overview of AcoustographyOverview of Acoustography

Single Sided Reflection ModeSingle Sided Reflection ModeAcoustography ApproachAcoustography Approach

Experimental SetupExperimental Setup

ResultsResultsConclusionsConclusions

Future DirectionsFuture Directions


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IntroductionIntroduction

Many structures and components in use todayMany structures and components in use todayrequire NDE inspection where access is limitedrequire NDE inspection where access is limitedto one sideto one side

These inspections are typically performed usingThese inspections are typically performed usingpoint by point or scanning techniquespoint by point or scanning techniques

Inspections of this type can be time consumingInspections of this type can be time consumingand typically require skilled operators forand typically require skilled operators fortesting and data interpretationtesting and data interpretation

Ideally, the development of a large areaIdeally, the development of a large area

inspection device would reduce these demandsinspection device would reduce these demands

Ultrasonic Inspections using single sidedUltrasonic Inspections using single sidedacoustography are being considered as aacoustography are being considered as apossible solutionpossible solution


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AcoustographyAcoustography

What is Acoustography?

It is the Ultrasound analog of: Real-Time Radiography

Digital Photography

Large area excitation and detection enable: Full field image formation

Near real-time results


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Basic Principle Image Formation

Analogous to x-rayimaging

AO Sensor allows near

real-time visualizationof ultrasound



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AO sensor contains a

layer of proprietary LC

material

LC molecules reorient

when exposed to

ultrasound Ultrasonically exposed

area becomes birefringent

showing contrast change

Basic Principle AO Sensor



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Acoustography ProcessAcoustography Process


Converts UT directly intoConverts UT directly intovisual image in near realvisual image in near real--timetime

Results compare well withResults compare well withthrough transmission Cthrough transmission C--scanscan

Conventional C-scan(5 MHz)

Acoustography(3.3 MHz)

Composite Sample AO Inspection

5 cm

5 cm

Single Flaw


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AcoustographySingle Sided Reflection Mode

Reflection mode acoustography enables single sidedinspection.

Ultrasound passes through AO sensor and interactswith material under test.

Images are captured using a CCD camera and framegrabber.

Differential response from AO detector at flaw locationsprovides image contrast


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Experimental ProcedureExperimental Procedure

Single sided acoustography tests wereSingle sided acoustography tests wereconducted on PMC materials subjectedconducted on PMC materials subjectedto impact damageto impact damage

Two reflection mode systems wereTwo reflection mode systems wereused, a laboratory system and aused, a laboratory system and aprototype handheld systemprototype handheld system

PulsePulse--Echo CEcho C--scans were performed onscans were performed onthe same samples and used as a basisthe same samples and used as a basisfor comparisonfor comparison


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Material

Polymer Matrix Composite (PMC)Polymer Matrix Composite (PMC)

AS4/3501, +/AS4/3501, +/-- 4545 LayLay--up, 4 x 3up, 4 x 3

Impact damaged Samples:Impact damaged Samples:

Sample #1: 15 Joule, 32 pliesSample #1: 15 Joule, 32 plies

Sample #2: 5 joules, 16 plies (just barely visible)Sample #2: 5 joules, 16 plies (just barely visible)

Samples were airSamples were air--backed to simulatebacked to simulate

real inspection situationreal inspection situation


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Experimental SetupExperimental Setup(Laboratory System)(Laboratory System)

Sample placed in water tank (airSample placed in water tank (air--backed)backed)

3 x 3 AO sensor placed on top of sample3 x 3 AO sensor placed on top of sample

2.5x2.5 3.3MHz transducer was placed above2.5x2.5 3.3MHz transducer was placed above

the AO sensor and powered forthe AO sensor and powered for 10 seconds10 seconds Images were acquired using a CCD cameraImages were acquired using a CCD camera

under polarized lightunder polarized light


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Experimental SetupExperimental Setup(Prototype System)(Prototype System)

Testeci en

OnB rer

OSensor

DScreen

Tr nsducer

E i t

cousticCoupling

First Prototype System(1 X 1 AO Sensor)

Handheld system usesHandheld system usessmaller (1x1) AO sensorsmaller (1x1) AO sensorfor portabilityfor portability

AO sensor coupled toAO sensor coupled tosample using ultrasonic gelsample using ultrasonic gel

Sound source coupled usingSound source coupled usingdistilled water in housingdistilled water in housing

3.3MHz sound source used3.3MHz sound source used

All components (soundAll components (soundsource, camera, AO sensorsource, camera, AO sensorand light contained in oneand light contained in one

unit)unit)


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Experimental Setup(Pulse Echo C-scan)

Commercial ultrasonicCommercial ultrasonicscannerscanner

Water immersion withWater immersion with

airair--backed samplebacked sample 3.5MHz focused3.5MHz focused

transducer closelytransducer closelymatches acoustographymatches acoustographyfrequencyfrequency

Images display peakImages display peakamplitude of back wallamplitude of back wallechoecho

Ultrasonic C-Scan System


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ResultsImpact Damaged PMC Sample #2

Reflection Mode AcoustographyImage Using Prototype System

(Approximate Area Shown by Red Square)

Reflection Mode AcoustographyImage Using Prototype System

(Approximate Area Shown by Black Square)

Pulse-EchoC-Scan


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ResultsResultsPMC Honeycomb Sample

Pulse-echo C-

Scan

Reflection modeacoustographyimage using

Prototypesystem (goodarea)

Reflection modeacoustographyimage using

Prototypesystem(Crushed corearea)


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ConclusionsConclusions Both laboratory and prototype reflection modeBoth laboratory and prototype reflection mode

acoustography systems are able to imageacoustography systems are able to imageimpact damage in PMC panelsimpact damage in PMC panels

Reflection mode acoustography was able toReflection mode acoustography was able toimage honeycomb structure and providedimage honeycomb structure and provided

indications related to crushed core regionindications related to crushed core region

Both systems demonstrated large areaBoth systems demonstrated large areaultrasonic imaging capability using a singleultrasonic imaging capability using a singlesided techniquesided technique

Acoustographic inspection requires minimalAcoustographic inspection requires minimalsetup and inspection time compared to Csetup and inspection time compared to C--scanscan

Results correlate well with ultrasonic CResults correlate well with ultrasonic C--scan atscan at

a similar frequencya similar frequency


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Future DirectionsFuture Directions

Refine prototype system for improvedRefine prototype system for improvedimage qualityimage quality Investigate interface materials and matchingInvestigate interface materials and matching

layerslayers

Reduce noise associated with ultrasonic sourceReduce noise associated with ultrasonic sourceinteracting with AO sensorinteracting with AO sensor

Develop and apply image processingDevelop and apply image processingtools for improved defect detectiontools for improved defect detection

capabilitiescapabilities Tools for use in through transmissionTools for use in through transmissionacoustography have been developed and willacoustography have been developed and willbe tailored for reflection mode usebe tailored for reflection mode use

Documents

ASNT Spring 2006-Final