Identification of Aging Aircraft Electrical Wiring Woolrich Engineering

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

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

Overview b History of the Problem b Triboelectric Effect b Project Objective b Wire Specimen b Lab Aging b Age Analysis b Work to be Completed

Triboelectric Effect b Static Electricity b Frictional force causes charge imbalance b Induced current • unwanted noise and interference b Magnitude is (“Identification of Aging Aircraft Electrical Wiring, ” December 2002) dependent on numerous factors

Project Objectives b Laboratory Aging • Simulate aging through: – temperature & humidity – Hot and cold – Jet-A fuel – saltwater solution – Temperature cycling – combination of all • Visual/Touch inspection b Age Analysis • Does age influence triboelectric effect? • Determine signal response to inputs • Relate age to measured triboelectric response • vibration wire current

Alpha Wire Specimen b Kapton b Alpha Wire 1632 b Alpha Wire 5825 (Alpha 1632) (Alpha 5852) • • • • too expensive hard to obtain Copper wire with rubber insulation 20 Gauge (thick) Stranded, Tinned Copper Rubber Insulation Low temperature tolerance -30 o to 90 o C 28 Gauge (thin) Stranded, Silver-plated Copper Teflon insulation -60 o to 105 o C Low Friction High Chemical Resistances

Overview b History of the Problem b Triboelectric Effect b Project Objective b Wire Specimen b Lab Aging b Age Analysis b Work to be Completed

10 x The Data Previous Cycle Remove 1 Sample at a Time Aging Process Test Sample and Do Not Return it New Cycle Aging Process Remove all 10 Samples Return Samples to Aging Process Test Samples

Current Work Phase I: Laboratory Aging b 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 ? b Corrosives • Jet-A fuel Soak – Visually obvious effects in previous work, swelling • Saltwater Soak • Residue Effects? – Graphite lubricant b Combination Cycle

Aging Equipment b Kitchen Ovens • Can’t run continuously b Drying Ovens • Remove humidity b Incubators • Most don’t get hot enough b Environmental Chambers • • Large temperature range Humidity Control Programmable Too expensive (A Bluem Environmental Chamber) (Courtesy of www. lunaire. com)

Aging Equipment b Zoology to the rescue! • Old Incubator – – Humidity control Adequate heat ? Working condition FREE ! (The Zoology Building (locked on Sundays)) (Courtesy of www. utexas. edu) • Old Freezer – – – No humidity control Needs cleaning FREE ! (The Freezer)

Anticipated Results b Material characteristics should change • • Texture Coefficient of Friction Capacitance Resistance b Changes should be reflected in the triboelctric response, and are expected to follow a detectable pattern.

Overview b History of the Problem b Triboelectric Effect b Project Objective b Wire Specimen b Lab Aging b Age Analysis b Work to be Completed

Current Work Phase II: Age Analysis b Reconfigure test setup to reduce Electro- Magnetic Interference (EMI) • • Separate data acquisition unit and signal amplifier Connect cases of all units to common ground Encase units in grounded foil to shield from EMI Test for presence of EMI using an EMF meter (to be acquired) • Make twisted pairs to partially cancel out magnetic inductance – Tighter twists are more effective

Anticipated Results Shaker/Wire Test Setup: • E = portion of energy output by shaker that is transmitted to wire through friction L V dx • E = σhoop(2πr. L)µk|dx| • V = V(d. E/dt, M 1, M 2) Wire R Shaker where M 1, M 2 are material properties • We expect to find an empirical formula that describes how V changes with age

Anticipated Results b It’s expected that µk, M 1, and M 2 all change in a predictable manner as the wire deteriorates b At any particular time, the voltage induced in the wire can be described as a specific function of the excitation frequency b It is unclear whether or not this frequency response will change as the material properties of the wire (µk, M 1, and M 2 ) change

Work to be Completed b Acquire aging equipment • Have freezer inspected by UT • Get technician from Labline to examine incubator b Build new wire testing apparatus b Cut and twist wire samples b Construct EMF shielding

Work to be Completed b Buy EMF meter to verify that EMI has been eliminated b Verify test setup b Acquire used wire from aviation scrap yard in Dallas b Conduct age analysis on wire specimens

Conclusion b History of the Problem b Triboelectric Effect b Project Objectives b Wire Specimen b Lab Aging b Age Analysis b Work to be Completed

Identification of Aging Aircraft Electrical Wiring QUESTIONS ?