Identification of Aging Aircraft Electrical Wiring Woolrich Engineering Consulting Firm Group Members: Robert Beremand Chad Hanak Melissa Straubel Sponsors: Dr. R.O. Stearman Marcus Kruger (“Identification of Aging Aircraft Electrical Wiring,” December 2002)

Overview History of the Problem Theory Project Objectives Experimental Setup Lab Aging Age Analysis Recommendations

History of the Problem Solutions –Visual inspection Impractical –Triboelectric response May indicate condition of wire (“Identification of Aging Aircraft Electrical Wiring,” December 2002) Faulty electrical wiring –Chafing and cracking insulation –Electrical fires –Arcing History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Triboelectric Effect Static Electricity –2 materials slide against each other Frictional force causes charge imbalance History Theory Objectives Experimental Setup Aging Age Analysis Recommendations (“Identification of Aging Aircraft Electrical Wiring,” December 2002) Induced current –Unwanted noise and interference Magnitude dependent on numerous factors

Project Objectives Laboratory Aging –Simulate aging through: Temperature & humidity –Hot and cold Jet-A fuel Saltwater solution Temperature cycling Combination of all –Visual/Touch inspection –Did not complete History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Project Objectives Age Analysis –Does age influence triboelectric effect? –Determine signal response to inputs –Relate age to measured triboelectric response –Vibration  Wire  Current –More successful History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Alpha Wire Specimen Kapton –Too expensive –Hard to obtain Alpha Wire 1632 –20 Gauge (thick) –Stranded, Tinned Copper –Rubber Insulation –Low temperature tolerance -30 o to 90 o C –Majority of testing was conducted on this type of wire (Alpha 1632) History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Test Setup HP Signal Analyzer software & DAS – means of interpreting signal and its response –Wanted to use IDEAS, bug in software Fixed sinusoidal vibration – determine triboelectric response at fixed frequency of wires of different ages History Theory Objectives Experimental Setup Aging Age Analysis Recommendations Signal Analyzer DAS Amplifier Shaker Wire Circuit Stinger Chessboard

Test Setup Stinger – transmit vibration from shaker to platform Chessboard – platform on which wire circuit was mounted History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Test Setup – Vertical vs. Horizontal Vertical –First used checkerboard- previous group –Structure is straight No loop antenna –More wire in contact with shaker surface (gravity) Horizontal –Grounded metal encasement to provide shielding from EMI –Strut –Longer stinger possible More distance between shaker and platform –One dimensional motion History Theory Objectives Experimental Setup Aging Age Analysis Recommendations (Horizontal test setup)

Wire Tension and Twisting New wire – tendency to untwist –Varied tension Did not notice real benefit to twisting new wire Consistent tension needed –Response varied with tension – can’t see trends –Mean decreased as tension increased –Standard deviation decreased even more Difficult to achieve uniform tension from wire to wire –Consequently, most test were conducted with the wire under no tension –Could change with better test setup History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Wire Orientation Improve consistency Orientation of wire on checkerboard appeared to affect amplitude of triboelectric response Affixed plastic hooks to board to insure uniform orientation of wire from test to test History Theory Objectives Experimental Setup Aging Age Analysis Recommendations (Wire orientation)

Examination of Twisting Dispute over effect of twisting on EMI and Triboelectric Effect –Connections and Current Flow Parallel and Series History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Laboratory Aging Temperature and Humidity –Previous success with heat alone Go hotter –Add Cold Test –Temperature Cycles, Temperature Extremes –Limited previous results from humidity alone Combine temperature and humidity exposure Freezing and Thawing –Tension test ? Corrosives –Jet-A fuel Soak Visually obvious effects in previous work, swelling –Saltwater Soak –Residue Effects? Graphite lubricant Combination Cycle History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Aging: 10x The Data Remove 1 Sample at a Time Test Sample and Do Not Return it Aging Process Remove all 10 Samples Test Samples Return Samples to Aging Process Aging Process Previous Cycle New Cycle History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Aging Equipment Kitchen Ovens –Can ’ t run continuously Drying Ovens –Remove humidity Incubators –Most don ’ t get hot enough Environmental Chambers –Large temperature range –Humidity Control –Programmable –Too expensive (A Bluem Environmental Chamber) (Courtesy of History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Aging Equipment Zoology to the rescue? –Old Incubator Humidity control Adequate heat ? Working condition FREE (eventually?) –Old Freezer No humidity control Needs cleaning FREE (eventually?) (The Freezer) (The Zoology Building) (Courtesy of History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Anticipated Results Material characteristics should change –Texture –Coefficient of Friction –Capacitance –Resistance Changes should be reflected in the triboelectric response, and are expected to follow a detectable pattern. History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Age Analysis Dispersed test setup components over large area to reduce Electro-Magnetic Interference (EMI) Attempted to verify repeatability with test setup Tested various sets of artificially aged wires to look for age-dependent trends in their triboelectric responses Separately enclosed shaker and test platform in grounded foil to further reduce EMI Arrived at some conclusions about test setup History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Anticipated Results dx Shaker Wire V E = portion of energy output by shaker that is transmitted to wire through friction E = f(σ hoop )(2πrL)µ k |dx| V = V(dE/dt, M 1, M 2 ) where M 1, M 2 are material properties We expect to find an empirical formula that describes how V changes with age L R Shaker/Wire Test Setup: History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Statistical Overview Fall 2002 group concluded triboelectric response amplitudes were random. Wire Response to 1KHz, 100mV sinusoid input (mV) Nominal Nominal Humidity 1 (3.5 days) Humidity 5 (17.5 days) Humidity 10 (35 days) History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Statistical Overview Hypothesis: points are not random, but centered about a fixed mean with a large variance (σ 2 ) Attempted to experimentally determine mean and σ 2 values to see if trends existed Each wire specimen was tested 15 times to provide sets of data to analyze Sample mean, σ 2, and accuracy of the sample mean were calculated for each wire History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Statistical Overview Sample mean: Sample variance: Prediction of true mean: where is the t-estimator, is the degrees of freedom, and is the accuracy percentage Source: Figliola, R. S., and Beasley, D. E. Theory and Design for Mechanical Measurements. John Wiley & Sons, Inc., New York, Pgs History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Verifying Repeatability Three new, untwisted wire specimens of the same length were tested (15 tests each) The wires were cut from different spools, and the test setup was shutdown and restarted before each wire was tested The wires were removed from the checkerboard and replaced in the same orientation between each individual test The results verify the test setup’s ability to reproduce results History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Verifying Repeatability History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Test Results Overview –Retested wires from Fall 2002 that were aged in Saltwater and Jet-A Fuel No statistically significant trends –Tested five wire samples that were aged at high temperatures in a conventional oven Inconclusive; needs more data points History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Jet-A Fuel-Aged Wires History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Oven-Aged Wires History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Recent Discoveries Grand majority of signal being measured was, in fact, EMI –Had thought that EMI was a significant, yet constant contributor to the measured response signal –Results show fluctuations in response signal are of the correct order of magnitude Coaxial cable that was used for most measurements was determined to be partially bad –Adds noise to signal that’s of the same order of magnitude as the triboelectric response signal History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Background Noise w/out Wire Attached (No Excitation) (This doesn’t change when the system is excited at 1kHz by the shaker.) History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Background Noise w/ Wire Attached (No Excitation) History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Bare Wire Response (No Insulation) History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Insulated Wire Response History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Recommendations Refurbish aging equipment –Have freezer inspected by UT –Get technician from Labline to examine incubator Attempt further eliminate noise and/or amplify Tribo Tension Crank History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Recommendations Buy EMF meter to determine what EMI remains in testing area (specifically, inside the foil enclosure) Use bare wire as control –Differential amplifier Acquire used wire from aviation scrap yard in Dallas –Scheduling conflicts prevented this from happening this semester History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Recommendations Use HP control program to capture response signal for a specified time and output to Matlab file –Could then do better statistical analysis on data and possibly cancel out ambient noise Learn new version of Ideas Frequency Response –Load Cell –Amplifier Phase Lag Verify our conclusions with EMI-reduced setup Follow our outline for ageing process History Theory Objectives Experimental Setup Aging Age Analysis Recommendations

Conclusion History of the Problem Theory Project Objectives Experimental Setup Lab Aging Age Analysis Recommendations

Identification of Aging Aircraft Electrical Wiring QUESTIONS ?