Post on 31-Mar-2015
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