Identification of Aging Aircraft Electrical Wiring

1
Identification of Aging Aircraft Electrical Wiring

• Woolrich Engineering Consulting Firm

(Identification of Aging Aircraft Electrical
Wiring, December 2002)
Group Members Robert Beremand Chad Hanak Melissa
Straubel
Sponsors Dr. R.O. Stearman Marcus Kruger
2
History of the Problem

• Solutions
• Visual inspection
• Impractical
• Triboelectric response
• May indicate condition of wire

• Faulty electrical wiring
• Chafing and cracking insulation
• Electrical fires
• Arcing

(Identification of Aging Aircraft Electrical
Wiring, December 2002)
3
Overview

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

4
Triboelectric Effect

• Static Electricity
• Frictional force causes charge imbalance
• Induced current
• unwanted noise and interference
• Magnitude is dependent on numerous factors

(Identification of Aging Aircraft Electrical
Wiring, December 2002)
5
Project Objectives

• Age Analysis
• Does age influence triboelectric effect?
• Determine signal response to inputs
• Relate age to measured triboelectric response
• vibration ? wire? current

• Laboratory Aging
• Simulate aging through
• temperature humidity
• Hot and cold
• Jet-A fuel
• saltwater solution
• Temperature cycling
• combination of all
• Visual/Touch inspection

6
Alpha Wire Specimen

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

(Alpha 1632)
(Alpha 5852)
7
Overview

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

8
10x The Data
Previous Cycle
New Cycle
9
Current Work Phase I 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

10
Aging Equipment

• Kitchen Ovens
• Cant run continuously
• Drying Ovens
• Remove humidity
• Incubators
• Most dont get hot enough
• Environmental Chambers
• Large temperature range
• Humidity Control
• Programmable
• Too expensive

(A Bluem Environmental Chamber) (Courtesy of
www.lunaire.com)
11
Aging Equipment

• Zoology to the rescue!
• Old Incubator
• Humidity control
• Adequate heat ?
• Working condition
• FREE !
• Old Freezer
• No humidity control
• Needs cleaning
• FREE !

(The Zoology Building (locked on
Sundays)) (Courtesy of www.utexas.edu)
(The Freezer)
12
Anticipated Results

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

13
Overview

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

14
Current Work Phase II Age Analysis

• 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

15
Anticipated Results
Shaker/Wire Test Setup

• E portion of energy output by shaker that is
  transmitted to wire through friction
• E shoop(2prL)µkdx
• V V(dE/dt, M1, M2)
• where M1, M2 are material properties
• We expect to find an empirical formula that
  describes how V changes with age

L
V
dx
Wire
R
Shaker
16
Anticipated Results

• Its expected that µk, M1, and M2 all change in a
  predictable manner as the wire deteriorates
• At any particular time, the voltage induced in
  the wire can be described as a specific function
  of the excitation frequency
• It is unclear whether or not this frequency
  response will change as the material properties
  of the wire (µk, M1, and M2 ) change

17
Work to be Completed

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

18
Work to be Completed

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

19
Conclusion

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

20
Identification of Aging Aircraft Electrical Wiring
QUESTIONS ?