Final Design Review

MEMS-based Corrosion Health Monitoring

Fri aei ynCucfed

Janine CrsohrO

Mihe ernc T io

Liaison Engineers: Pec uces

Tr lw

Faculty Coach: Jh .AboePD E

Introduction Corrosion occurs on electronic chassis of aircraft

causes loss of integrity of EMI seal

Lockheed Martin technicians responsible for avoiding critical corrosion damage monitor the health of the chassis on a scheduled basis

the chassis is relatively inaccessibleinaccessible within the aircraft in most cases, the chassis is corrosion freecorrosion free time and money are wastedwasted by this inefficiency

AimTo reduce unnecessary corrosion related service

activities with a stand alone system that can alert a technician of a needed inspectionReliable measurement of the environmental

corrosivity seen by the chassisLED alert system

viewed from exterior of the chassis 1-10 level of need for service activity

Business Case

Life cycle cost for the Apache Helicopter fleet* $14.3 billion Percent Dedicated to Inspection** x 25%

------------------ Inspection cost for the Apache Helicopter $3.575 billion Percent inspections eliminated by SDX-4912 x 33%

------------------ TOTAL PROGRAM SAVINGS $1.18 billion Life cycle of Apache helicopter* ÷ 20 years

------------------ TOTAL ANNUAL SAVINGS* $59 million TOTAL LIFE CYCLE SAVINGS/helicopter*** $1.5 million

*These estimates, in constant fiscal 1994 dollars, are provided in Annex D of the Longbow Apache Test and Evaluation Master Plan, which cites December 1993 estimates from the Longbow Program Office and the President’s fiscal 1995 budget as the original source.

**Provided from the Military Analysis Network created by the FAS, Federation of American Scientists (non-profit, tax exempt, 501c3 organization)***Costs assuming that the SDX-4912 is installed in full apache fleet (assuming fleet size ≈ 800)

Elements of Chassis Galvanic coupling of aluminum

and nickel

Aluminum = anode Nickel = cathode

Electrolyte provides driving force for corrosion

Galvanic CorrosionAs a result of nickel

contact:Corrosion potential

of aluminum (M) increased

Corrosion rate of aluminum (M) is increased

Nickel

Aluminum

Couple

Customer Requirements

GENERAL NEEDS:

Operate Under Harsh ConditionsNon-Intrusive Feedback

Long Life SpanMEMS BasedLight WeightSmall Size

Hardware Design

Hardware Design

Sensor(s)

Processing

Feedback

Aircraft In-situ Operation

Power Supply

Location

Aircraft Structure

Maintenance Opportunity

Storage

Functional Diagram

Hardware Design

Dimmed elements denote exploratory efforts not included in final design

Macroscopic System

Hardware Design

Near Linear Approximation Module Expiration

Detection Manufacturability

R = V / Iappl

R = ρL / πr2

Electrical Resistance Sensor Concept:

Sensor Sampling Data sample taken hourly

All data stored on Flash

Light Emitting Diodes (LEDs) 4 red, 3 yellow, 2 green 1-10 level of corrosion damage

Relate to need for technician to perform service activity Level 7 (1st Red LED) correlates to critical corrosion damage

Output MethodCorrosion will cause reduction in ER sensor’s

cross-sectional areaAt critical % area reduction critical voltage

A

Theoretical Voltage v. Area

6.00E-05

7.00E-05

8.00E-05

1.98E-072.08E-072.18E-072.28E-072.38E-072.48E-072.58E-072.68E-072.78E-07

Cross-sectional Area (m2)

Vo

ltag

e (V

)

Sensor Sampling

Control Wire

Testing

Verification Testing

Hardware Unit TestSensor Proof of Concept5 days in Salt Spray Machine

Software Unit TestData Interface to software and LED display

Acceptance Testing Functional Acceptance Test (Integration)Environmental Acceptance Test (Survivability)

Proof of Sensor Concept 48 hour test

-24 hours immersed in salt bath

-24 hours in atmosphere

Proof of Sensor Concept Ground to 50% diameter along

longitudinal plane and polished Large cathode (Ni) to anode (Al)

ratio

Damage to nickel plating on aluminum wire

Testing

ASTM B117 Salt Fog ChamberConstant corrosive vapor applied for 5 days5 Test coupons removed at daily intervalsData samplings recorded as voltages

Recorded using a datalogger Data sampling = once per minute

Example of Salt Spray Chamber

Wireless - ZigBee

Proven feasible up to 6” thickness of casingDue mainly to chamber reflectionsMinimal aperture required

Wireless communication

pursuit ended 2/7/05

given risk and manpower

Testing Results

Results

Salt Fog Testing

-0.5

0

0.5

1

1.5

2

2.5

3

0 12 25 37 50 62 75 88 126

Time (Hours)

Vo

ltag

e (V

olt

s) Corrosion Sensor

Corrosion Sensor Control

Humidity

Temperature

Circuit Control Voltage

Coupon 1 Coupon 2 Coupon 3

Results ASTM D3359 Coating Adherence Test

Measures Amount of Undercut Nickel Plating Designations: 5A (Least Corrosion)–0A (Most Corrosion) 5 coupons tested

24 hr: 5A 48 hr: 4A 71 hr: 2A 139 hr (1): 1A 139 hr (2): 2A

Coupon 139 hr (1)

Measurement CorrelationCoupons

Minimal corrosion product for 24 & 48 hr coupons Visible Al203 for 71 &139 hr coupons

Measurements Rapid Increase in ER sensor at onset

Minimal Corrosion Product forming Al+3 ions lost in aqueous solution

Resistance change levels off Corrosion product protection

Sensor Lifespan

Electrical resistance sensor Survived 5-day salt fog Provided data throughout lifespan of operating board

Temperature Survived 2-day salt fog

Humidity Survived 1-day salt fog Potentially a conformal coating problem on board

Environmental SurvivabilityHarshest of Possible Environments

Environmental Sensors not conformally coated survivable in constant spray for 1-2 days

Macroscopic System conformal coating spot failures spot corrosion

emitted heat from conducting wires

survivable in constant spray for 4 days

Prototype Demonstration

Salt Fog Testing

-0.5

0

0.5

1

1.5

2

2.5

3

0 12 25 37 50 62 75 88 126

Time (Hours)

Vo

ltag

e (V

olt

s) Corrosion Sensor

Corrosion Sensor Control

Humidity

Temperature

Circuit Control Voltage

Coupon 1 Coupon 2 Coupon 3

LEVEL 7

1 2 3 4 5 6 7

Conclusion

Recommendations

Wireless LinkStand-Alone Custom GUI Additional Low Power ResearchLaser Etched Sensor Manufacturing

Acknowledgements

Thank You… Lockheed Martin

eyunss lew ling Kaara

University of Florida ohnAoPE ithanfillD, an M Marilyn Marlow

QuestionsQuestions