Transcript Analog Interfaces - The International Aviation Safety

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.
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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 Aging
PERCENT RETENTION OF ELONGATION: 110 MIL PVC JACKET ON AIW 750
MCM
% ROE @126°C
% ROE @136°C
Hours of Aging
328
336
296
304
312
320
272
280
288
240
248
256
264
216
224
232
184
192
200
208
160
168
176
128
136
144
152
104
112
120
72
80
88
96
48
56
64
16
24
32
40
104%
102%
100%
98%
96%
94%
92%
90%
88%
86%
84%
82%
80%
78%
76%
74%
72%
70%
68%
66%
64%
62%
60%
58%
56%
54%
52%
50%
0
8
Retention of Elongation
% ROE @116°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
PVC
PVC (MIL-W-5086/2)
1000
Rated @ 105°C: 1.54 eV and b= - 16.50
Life (Years)
100
Unknown Rating: 0.99 eV and b = -10.00
10
1
35
40
45
Source: Citation 461 of EPRI NP-1558
50
55
60
Temperature (°C)
65
70
75
80
85
Indenter Modulus (lbs./in)
600
580
560
540
520
500
480
460
440
420
400
380
360
340
320
300
280
260
240
220
200
180
160
140
120
100
80
Elongation-At-Break (%)
Indenter Modulus vs. EAB for neoprene
NEOPRENE
220
200
180
160
140
120
100
80
60
40
20
0
Indenter Modulus vs. Retention of EAB for PVC
Jacket
AIW 750 MCM:
PVC JACKET MODULUS VERSUS RETENTION OF ELONGATION
600
575
550
525
500
450
425
400
375
350
325
300
275
250
225
200
175
110%
100%
90%
80%
70%
60%
50%
40%
30%
RETENTION OF ELONGATION AT BREAK
20%
10%
150
0%
MODULUS (LB/IN)
475
Life Projection Curve
Overview of Software and Testing
Key software features
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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
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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 is
slope of this line
Analysis - Vs. Time
VELOCITY
FORCE
DISPLACEMENT
Relaxation Mode
Probe
moves to
fixed force
and 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
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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