Dielectric Measuring Tool for Radome Checkout

8/3/2019 Dielectric Measuring Tool for Radome Checkout

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Information disclosed in this document was developed under the U.S. Government Small Business Innovation Research (SBIR)program. The information contained in this document is considered proprietary in nature by the author(s) and any disclosure is subject

to the restrictions under Public Laws and supporting regulations governing this program. Use or disclosure outside of the U.S.

Government of any information contained within this document without the expressed written consent of the author(s) is hereby

prohibited. Further, release or disclosure of any information within the U.S. Government is restricted to that necessary to support the

expressed purposes of the SBIR program. This restriction is to be retained with any and all parts of this document that are so

distributed.

Dielectric Measuring Tool forRadome Checkout:

Prototype DevelopmentTexas Research Institute POC:

Russell Austin

(512) 263-2101

amntlPOC:

Reza Zoughi, Ph.D.

(573) 341-4656

OC-ALC COTR/TPOC:

Todd Bayles

(405) 662-7384

OC-ALC FFR Manager

Jess Phillips

(405) 734-0229


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Information disclosed on this page was developed under the U.S. Government Sma ll Business Innova tion Research (SBIR)program. The informa tion conta ined on this page is considered proprietary in nature by the author(s) and any disclosure is

subject to the restrictions as stated in the cover sheet of this document.

Background Repaired Radomes Inspected with Moisture Meter

& Tap Testing

Inspection Requires 4 Passes over the Radome

Moisture Meter & Tap Testing

Interior & Exterior Skins Tap Testing:

May Not Accurately Determine Boundaries of Debond

Operator Dependant Potential for Larger Repair Than Required

Moisture Meter Not Always Accurate


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Relationship Between FFR & Repair Repaired Radomes sent to Far Field Range (FFR)

to Test Radar Performance Approximately 40% of Repaired Radomes Fail

FFR

However: FFR Radar Performance Results cannot accurately

determine location, extent or type of imperfectioncausing a performance failure

Radar Performance Problems not Always Related to a

Discrete Physical Flaw


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Return to Repair Facility Radome is Returned to Repair Facility after FFR

Failure Current inspection methods available to repair

personnel:

provide no quantitative measurements cannot estimate if a radome will pass FFR tests

only detect discrete flaws, not radar problems

Repair Personnel Have no Guidance on How toAlter the Radome so it will Pass FFR


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TRI/amntl Solution Show feasibility of millimeter wave reflectometry

to solve radome problems detect presence of various flaws of interest

detects flaws regardless of depth

locates flaw edges fast, simple

detects transmission problems even if no discreteflaw exists

more complex quantitative measurements canmeasure phase and amplitude of reflections


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Samples with Known Flaws Manufactured by Applied Aerospace

Structures Corp (AASC) Air Force radome manufacturer

Fiberglass skins (6 layers top, 4 layers bottom)

Honeycomb core (0.75 thick phenolic with 0.25diameter cells)

Debonds & Delaminations Crushed Core

Core Thickness Variations


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Sample Design Flaws:

Debonds at BothSkin/Core interfaces

Delams in Both Skins

Crushed Core & Core

Thickness Variations Water Ingress

Thickness: 8 to 20

mils Cross Section: 0.25

to 1


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Sample Construction


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Basis of Method Finite Energy

All incident energy willhave some reflectionand some transmission

Change intransmission causes achange in reflection

Quantifying reflected signals phase andmagnitude allows quantification of transmissionproblems


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Microwave Image 24 Flaws Obvious

4 Flaws NotObvious

3 in middle of lowerskin (12 mils thick)

1 is 0.008 thickcrushed core nearlower skin

Appears to showadditional features

Excess adhesive?


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Higher Resolution Image All Flaws Detected

More ComplexEquipment thanPrevious Image


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Water Ingress 0.1 cc water injected

into a single cell of thehoneycomb

First 6 images made

over 2 days Final image made after

emptying cell of water


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Hand Scans Video

Technique is simple and real time Accurately detects radar performance anomalies

& locates flaw edges (independent of flaw depth)

Output is Simple DC Voltage could power needle gauge or light LEDs (green, yellow, red)

proper analysis can provide quantitative phase and

magnitude data COTS camcorder battery runs it for a week

Cost Comparable to Other Flaw Detectors


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Correlate Test Data to Flaws Edges of all flaws located accurately regardless of

flaw type or depth

no need for complex signal analysis nor operatorinterpretation of data

No ambiguity in locations of flaws

Simple Equipment:

All flaws except 8 mil core crush at far face anddebonds embedded in middle of far face detected

Complex Equipment:

All flaws detected


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Small B-52 Radome Sample

Two Previous Repairs

Build Up of Radome Coatings

Radar Performance Unknown

Note Center of Circular Repair and Large Repair


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Small Sample Results No NDI Indication:

Various Coatings Large Repair

Smaller Circular

Repair

Large Indication

Joint of LargeRepair andCircular Repair


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Large B-52 Radome Sample

Three Previous Repairs (two through wall, one exterioronly)

Passed Radar Performance Testing

No NDI Indications (Even where Repairs Overlap)

Video of B-52 Radome Inspections Available


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Highlights So far, no False Positives

Not radome specific - can be applied to radomes at allthree ALCs

Detect Radar Anomalies, even if not caused by a discreteflaw

Accurately determine size of radar anomaly regardless ofdepth

Requires little operator training/data interpretation

Quantitative phase and amplitude data can be used topredict FFR performance


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Cost/Cycle Time Reduction Depots currently go over each radome four times.

This technology will require one time inspection labor reduced 75%

B-52 Nose Radome Cycle Time

44 days 6 days for inspection

Millimeter Wave Inspection Reduce Cycle Time by 4.5Days


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Major Savings Current FFR failure rate for repaired radomes is

~40% Each Rebuild Costs $20k

OC-ALC Rebuilds about Three Dozen B-52 Nose

Radomes per Year B-52 Repair Facility Savings: $288k per year

FFR Savings: testing fewer radomes that will fail

Savings for More Numerous Aircraft (130, 135etc) Scales


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Current Status Field Prototype Development Started

Develop handheld sensor for detecting and sizingflaws:

crushed core, delams, fluid ingress, thicknessvariations

radar anomalies

Implement Two Reflectometers Built AroundSensor

Handheld go/no go

Quantitative measurement of phase and amplitude

data can be used to predict FFR performance


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Go/No Go Prototype Handheld Probe:

battery powered rugged enclosure

audible/visual alarm (e.g. buzzer, LED, needle deflection)

adjustable amplifier adjustable alarm trigger

Calibration:

known good section look at several places on radome and assume smallest

signal is good


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Quantitative Version Essentially Similar Hardware as Go/No Go

Electronics in Handheld Unit AutomaticallyDisplays Quantitative Phase and AmplitudeMeasurements

Quantitative Data Used by FFR Personnel toDetermine Location and Severity of RadarAnomalies


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Most Important Result Determining if a

Radar Window WillPass FFR TestingWithout Expenseand Effort of FFRTesting

Allowing FieldPersonnel to QualifyRadome Repairs


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Information disclosed on this page was developed under the U.S. Government Sma ll Business Innova tion Research (SBIR)

program. The informa tion conta ined on this page is considered proprietary in nature by the author(s) and any disclosure is


Both Prototypes Tested on Existing Samples from Phase I

Field tests at OC-ALC, WR-ALC andcommercial facilities

B-1

B-52

E-3

Provide Automated Prototypes with UserManual


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Information disclosed on this page was developed under the U.S. Government Sma ll Business Innova tion Research (SBIR)

program. The informa tion conta ined on this page is considered proprietary in nature by the author(s) and any disclosure is


Contact InformationRussell Austin

Texas Research Institute

415 Crystal Creek Dr.Austin, TX 78746

(512) 263 - 2101

[email protected]

Reza Zoughi, Ph.D.Applied Microwave NDT Lab

University of Missouri Rolla

224 Emerson Electric Co. Hall

Rolla, MO 65409

(573) 341-4656

[email protected]

Jess Phillips76 CMXG/MXCPATinker AFBVoice: 405-734-0229

[email protected]

Dielectric Measuring Tool for Radome Checkout

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