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Outline of Presentation
• Introduction to Analog Interfaces, Inc.
• Introduction to the Indenter Polymer Aging Monitor
• Principle of Indenter measurements
• How aging correlations are done
• Overview of software and test taking
• Overview of FAA contract
Analog Interfaces, Inc.
• Data Acquisition products• Hardware and software• Portability - emphasis• RS-232 (serial) front ends• Standard 16 channel product “BLACK LAB”• Most of work has been on custom OEM
products
Black Lab General Purpose System
AirCEt - Air Operated Valves
Calplex
Introduction to Indenter
Indenter Polymer Aging Monitor
• Provides information on aging of wires
• Market at this point primarily nuclear
• Systems in use in U.S.; UK; Sweden; Russia; France; Canada; India
• Product in field use for about 10 years
• Marketing partner AMEC Earth and Environmental (formerly Ogden)
• William M. Denny - materials consultant
Principle of Indenter Measurements
Overview of Indenter Principle
• Small probe is moved into cable insulation
• As probe moves, force and displacement readings are recorded until the force reaches a preset value
• Force and displacement readings are cross plotted
• Slope of this plot is called “Modulus”
• Modulus is later correlated with aging
Diagram of probe movement
Modulus Calculation
Indenter System Components
Data acquisition box
Cable Clamp Assembly
Indenter System
Clamping mechanism
Small Wire Insert
Clamp Head
Small Wire Insert
Adapt technology to aircraft wires
• Natural extension to nuclear area
Differences in:
• Sizes
• Types of material
• Accessibility
• FAA contract to make this transition
How Aging Correlations are done
Relationship Modulus to Aging
• Objective of taking modulus readings is to provide data on wire condition
• This is done by correlating modulus values with data obtained from elongation-at-break (and possibly other) tests
• Following discussion shows how this is done - examples from nuclear industry
Mechanical vs. electrical failure
• Concern is with insulation cracking
• Cracking occurs because insulation has lost flexibility - ability to stretch when subjected to tensile load has been reduced to zero
• Elongation reduces as cable insulation is subjected to elevated thermal environments
• Mechanical property - elongation - must decrease significantly before electrical property affected
Elongation-at-break (EAB)
• Mechanical failure precedes electrical failure
• Monitor mechanical degradation by EAB
• % EAB used to provide safety margins
• Nuclear Industry 40% cutoff for critical equipment
• 20% for non-critical
Modulus - EAB Correlation
• Cables artificially aged using accelerated thermal aging
• At fixed time intervals, samples are removed and tested for EAB and modulus values also taken
Retention EAB vs. Hours AgingPERCENT RETENTION OF ELONGATION: 110 MIL PVC JACKET ON AIW 750
MCM
50%52%54%56%58%60%62%64%66%68%70%72%74%76%78%80%82%84%86%88%90%92%94%96%98%
100%102%104%
0 8 16 24 32 40 48 56 64 72 80 88 96 104
112
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128
136
144
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184
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232
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304
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328
336
Hours of Aging
Re
ten
tio
n o
f E
lon
ga
tio
n
% ROE @116°C % ROE @126°C % ROE @136°C
Arrhenius thermal life curve
• Using previous graph, pick off values from three curves AT SAME ELONGATION VALUE
• These values used in regression analysis to obtain classic “Arrhenius thermal life curve” shown in the next graph.
PVC Insulation - Thermal Life
PVC Insulation - Thermal Life Comparison
1
10
100
1000
35 40 45 50 55 60 65 70 75 80 85
Temperature (°C)
Lif
e (Y
ears
)
PVC PVC (MIL-W-5086/2)
Rated @ 105°C: 1.54 eV and b= - 16.50
Unknown Rating: 0.99 eV and b = -10.00
Source: Citation 461 of EPRI NP-1558
Indenter Modulus vs. EAB for neoprene
NEOPRENE
0
20
40
60
80
100
120
140
160
180
200
220
80
10
0
12
0
14
0
16
0
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60
0
Indenter Modulus (lbs./in)
Elo
ng
ati
on
-At-
Bre
ak
(%
)
Indenter Modulus vs. Retention of EAB for PVC Jacket
AIW 750 MCM:PVC JACKET MODULUS VERSUS RETENTION OF ELONGATION
150
175
200
225
250
275
300
325
350
375
400
425
450
475
500
525
550
575
600
0%10%20%30%40%50%60%70%80%90%100%110%
RETENTION OF ELONGATION AT BREAK
MO
DU
LU
S (
LB
/IN)
Life Projection Curve
Overview of Software and Testing
Key software features
• Required data entry location, material, etc.
• Multiple opportunities to enter notes
• Database saves all test setup info, notes, etc.
• Automatic generation of reports
• Easy export to spread sheets
Setup screen - material
Setup - test parameters
Velocity
Peak Force
Test taking
• Wire “clamped” in jaw
• Test is taken
• Clamp moved to different location
• Five to ten tests = “test session”
• Recorded modulus value is average of individual tests in test session
Test taking Screen
Listing of test sessions
Analysis - Cross Plot
Modulus isslope of this line
Analysis - Vs. Time
FORCE
DISPLACEMENT
VELOCITY
Relaxation Mode
Probe moves to
fixed forceand then
holds there
Reports -Setup
Reports - Notes
FAA Contract Work
• Title - Material Testing Research and Indenter Equipment Modifications for Determining Aging of Wires in Aircraft
Two Main Areas:
• Material related
• Redesign of present Indenter hardware/software
Material Testing
• Polyimide (Kapton)
• Power feeder
• Cross linked ETFE (Tefzel)
• TKT (Teflon / Kapton / Teflon)
Reference Wire
• Simple wire construction
• To be used for comparison with nuclear data to determine or confirm that small diameter wires perform in similar manner
• Will use PVC
Validation Plan
• Testing to be done by independent group
• Samples to be randomly numbered
Industry Database
• Test results
• Data from other testing (like nuclear)
• Material specifications
Cable Clamp Redesign
Objectives:
• Lightweight
• Easy to hold
• No greater than 1.25” in diameter
• Can access wires in tight locations
• Molded plastic outer construction
Portability Mockup
Design for Portability
Hardware Design Objectives
• Portable - worn on belt
• Light weight
• Ease of use by operator
Software Changes
• When testing in the field, a notebook PC will not be used
• New software will provide for transferring test parameters and data back and forth between a host PC
Summary
Advantages of Indenter tests for aging:
• Non-destructive
• Done in actual locations in aircraft
• Easy and fast to acquire test data
• Once the relationship between the modulus readings and aging is established for a wire type, determining the wire’s condition is then possible
Other inputs sought
• If your organization has data or inputs that would be helpful to this study or you would like to include your data in the database, we’d like to discuss this with you.
• THANK YOU for the opportunity to make this presentation