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NASA Contractor Report 189101
High Temperature Strain GageTechnology for Hypersonic AircraftDevelopment Applications
W. L. Anderson and H. P. Grant
United Technologies Corporation
Pratt & WhitneyCommercial Engine BusinessEast Hartford, Conn. 06108
February 1992
Prepared forLewis Research CenterUnder Contract NAS3-25410
National Aea'onauties andSpace Administration
(NASA-CR-189101)
GAGE TECHNOLOGY
DEVELOPMENT
HIGH TEMPERATURE STRAIN
FOR HYPERSONIC AIRCRAFT
APPLICATIONS (PWA) 56 pCSCL 16B
G3135
N92-22239 _;
Unclas
0083767
https://ntrs.nasa.gov/search.jsp?R=19920012996 2020-04-02T16:41:06+00:00Z
FOREWORD
This report presents the results of an experimental evaluation of two types of
wire strain gages each on two types of substrate materials applicable to
hypersonic aircraft development. The evaluation was conducted under the "High
Temperature Strain Gage for Hypersonic Aircraft Development Application"
program under Contract NAS3-25410.
The original Pratt & Whitney Program Manager was Howard P. Grant who retired
in September 1989. He was replaced by Mr. Wilbur L. Anderson who served as
Program Manager for the remainder of the program. Acknowledgements are given
to Mr. Richard G. Claing and Mr. Armand 3. Latraverse who were involved in the
test preparation and strain gage installation, respectively.
ii
PRECEDING PAGE BLANK NOT FILMED
TABLE OF CONTENTS
Section
i. 0 SUMMARY
2.0 INTRODUCTION
3.0 EXPERIMENTAL DESIGN AND TEST PLAN FORMULATION
Test Equipment
Test Specimen DesignInstrumentation of Test Bars
Test Procedure
Apparent Strain Testing
Drift Testing
Gage Factor Testing
Creep Testing
Test Circuitry
4.0 TEST PERFORMANCE AND ANALYSIS OF RESULTS
Palladium Chromium Gages
Apparent Strain Data (PdCr)
Drift Data (PdCr)
Gage Factor Data (PdCr)
Creep Data (PdCr)
BCL-3 Gages
Apparent Strain Data (BCL-3)
Drift Data (BCL-3)
Gage Factor Data (BCL-3)
Creep Data (BCL-3)
Comparison of Results
Comparison of PdCr to BCL-3 on IN100
Comparison of PdCr to BCL-3 on CuZr
Comparison of IN100 to CuZr for PdCr
Comparison of IN100 to CuZr for BCL-3Insulation Resistance Data
Thermo-electricity Data
Post-test Inspection
5.0 CONCLUSIONS
PdCr Gages
BCL-3 GagesGeneral
6.0 REFERENCES
APPENDIX
Report Documentation Page
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SECTION 1.0
SUMMARY
A program was conducted to evaluate two types of wire strain gages each on two
types of substrate materials applicable to hypersonic aircraft development.
The program was conducted under Contract NAS3-25410, "High Temperature Strain
Gage for Hypersonic Aircraft Development Applicatlons" with the objective of
establishing the extent to which the temperature llmltatlon of 700K (801°F)
can be overcome by employing two advanced gage alloys: a new palladlum-13_
chromium alloy and a basellne Iron-chromlum-alumlnum alloy. The specific
objective was to establish the durability and accuracy of wire strain gage
systems under simulated hypersonic aircraft operating conditions.
Two alloy wire strain gages, Pd 13_ Cr (by weight) and BCL-3, on IN100 and
Cu .15_ Zr alloy substrates were evaluated. The PdCr and BCL-3 strain gages
were designed by Pratt & Whitney and Battelle-Columbus Labs, respectively, and
installed on test bars. The gages were connected to Wheatstone bridge circuits
and the outputs were recorded on a microcomputer based acquisition system.
Four types of testing were conducted on the strain gages:
i. Apparent strain testing: zero shift with temperature.
2. Drift testing: zero shift with time, without strain.
3. Gage factor testing: strain sensitivity.
4. Creep testing: zero shift with time, with strain.
Results of the testing have shown the strain gages to have good resistance
stability as summarized below:
o PdCr gages have good resistance stability below 866K (1100"F), the Pt
temperature compensation element is effective and the drift rate is
reduced by a NiCrA1 coating.
o BCL-3 gages have good resistance stability above 800K (981"F) but the
drift is high at 700K (800°F).
Insulation resistance is less then one megohm above 900K (II61@F) and
the thermo-electrlc effects of both gage types are low with the lead
configurations tested.
SECTION2.0INTRODUCTION
The objective of this work is to establlsh a technology base for use of high-
temperature wire-form static strain gages on materials applicable to hypersonic
aircraft development at temperatures above 800K (981°F).
A goal in the field of aeronautical research is the development of hypersonic
aircraft capable of flying take-off to orbit or transporting people to the far
Pacific basin in a few hours. Because of the high speeds involved, such
aircraft will have structures that are subject to high temperatures (more than
800K) and very high heat fluxes. In the development of such aircraft, there
will be a need for hlgh-temperature static strain measurement which is beyond
the state-of-the-art strain gage technology. This work is intended to
contribute to the technology of hlgh-temperature static strain measurement on
materlals and under conditions that are pertinent to hypersonic aircraft
development needs.
The strain gage alloys which have the highest potential for static strain
measurements at temperatures above 800K are those of the FeCrA1 family and
those of newly developed PdCr. The FeCrAI alloys have a relatlvely low but
nonlinear electrlcal-reslstance-versus-temperature character and good
oxidation resistance. The FeCrA1 alloy selected for this work is BCL-3,
developed under NASA sponsorship at Battelle-Columbus Labs (Ref. i). The PdCr
alloy has a falrly llnear electrlcal-reslstance-versus-temperature character,
but a temperature-coefflcient-of-reslstance high enough that a thermal
compensation scheme is needed. It also has fair oxidation resistance. The PdCr
alloy selected for this work is 87_ Pd and 13_ Cr (by weight), developed under
NASA sponsorship by the United Technologles Research Center (Ref. 2).
Because of the high temperature and very high heat flux expected in the
hypersonic aircraft structure, the structure must be fabricated of an uncooled
hlgh-temperature material or a cooled low-temperature material. If a cooled
material is used, the thermal conductivity should be high. The high temperature
material selected for this work is IN100 ( 59_ Ni, 15_ Co, 9.5_ Cr, 5.5_ AI,
4.8 Ti, 3_ Mo, i_ Fe, I_ V and 1.2Z other) and the low temperature material
99.85_ Cu and .15_ Zr.
SECTION3.0EXPERIMENTAL DESIGN AND TEST PLAN FORMULATION
Test specimens were designed for use with existing test fixtures and for the
four types of tests listed below to be conducted on the strain gages:
i. Apparent strain testing: zero shift with temperature.
2. Drift testing: zero shift with time, without strain.
3. Gage factor testing: strain sensitivity.
4. Creep testing: zero shift with time, with strain.
TEST EQUIPMENT
Existing strain gage test equipment, shown in Figure I, was used for all four
types of tests. It includes the bar bending mechanism, a 25.4 cm (10") long
tube furnace, a temperature indicator, an oven temperature control, a bridge
connection box and a Hewlett-Packard data acquisition system. The test bar
bending mechanism, shown in Figure 2, consists of a vise to hold the clamping
fixture and a stepping motor driven deflection device. The clamping fixture,
with a test bar (old design) installed, is shown in Figure 3.
TEST SPECIMEN DESIGN
Test bars 20.3 cm (8") long, 3.5 cm (1-3/8") wide and .64 cm (1/4") thick were
fabricated as shown in Figure 4. Only bars intended for gage factor and creep
testing were fabricated with the tapered section, the others being rectangular.
The purpose of the taper is to provide constant strain over the active length.
The PdCr strain gages were designed by Pratt & Whitney as shown in Figure 5.
The large grid size, .76 cm (.3") square, is needed to obtain a high enough
gage resistance (about 58 Ohms) for good measurement with the large wire
diameter (and low resistance). Pt was selected for the thermal compensationelement because of the stable resistance characteristics and high temperature
coefficient of resistance. The 3.3 Ohm resistance is designed to provide the
right amount of compensation in a 1:1 bridge. The .16 mm (6.3 mil) diameter Ni20_ Cr leadwires are larger than desirable, but necessary to keep the
resistance low relative to that of the gage grid. Lead resistance is about 4.6
ohms.
The BCL-3 strain gages were designed by Battelle-Columbus Labs as shown in
Figure 6. The grid size is standard for this 120 Ohm gage. The FeCrAI ribbon
(Hoskins alloy 875) lead is a standard used by Battelle. Lead resistance is
about 2.9 ohms.
Installation of the gages and thermocouples on the test bars is shown in
Figure 7. The gage leads are about 6.35 cm (2.5") long, being spliced to Ni
Clad Cu wire about 2.54 cm (1.0") from the end of the bar. The splice is
brazed with Nicrobraz 150 (from Wall Colmonoy Corp.). The prep coat of NiCrA1
(Metco 443), precoat and overcoat cover the shaded areas. The thermocouples
are made of .2 mm (8 mil) diameter, type K wire, with the Junction welded
prior to installation on the precoat. A non-precoated area was left on side 1
for the installation of a reference strain gage (WK-06-062AP-350 from
Measurements Group) prior to the gage factor tests. The types of bars gages,
precoats and overcoats are as follows:
3
ORIGTNAL PAGE
BLACK AND WHITE PHOTOGRAPH
Figure i.- Strain Gage Test Equipment
O0
Figure 2.- Test Bar Bending Mechanism
4
ORYGINAL PA('_E
BLACK AND WHITE PHOTOGRAPH
Figure 3.- Test Bar Clamp Fixture
1.385"/-L1.365"
8.000"7.980" 3.010"
2.990"
2.510"- I- 2.490"
.257"!
-- I
/2'_ k-"152o"/ .500"
.375"
iT'
.258"
.254"
JI
I I
SURFACE FINISH 15 MICRO-INCH A-ABOTH SIDES IN TAPERED SECTION
ALL EDGES TO HAVE .030" RBREAK OVER CENTER 4" OR MORE
Figure 4.- Strain Gage Test Bar
!
0.30-_0"
±
0.300'L-.----_-
P
GRID: 0.00176 INCH DIA. WIRE
_: 58 OHMS
_J_E_=_: 0.001 INCH DIA.PLATINUM WIRE
_: 3.5 OHMS
_: 0.0063 INCH DIANi 20Cr WIRE
LEAD ATTACHMENT: PARALLELGAP WELD
FABRICATED AT PRATT & WHITNEY
LEAD A LEAD B LEAD C
Figure 5.- Palladium 13Z Chromium Dual Element Strain Gage
m
Figure 6.- FeCrAI (BCL'3)
! GRID: 0.00167 INCH DIA. WIRE
_: 122 OHMS
_: 0.032 INCH X 0.002 INCHHOSKINS ALLOY 875 RIBBON
LEAD ATI'ACHMENT: TACK WELD SANDWICH
FABRICATED AT BATTELLE
Strain Gage
6
REFERENCE GAGENICLAD C.,u, 15 MIL WK-06-062AD-350
GAGE #1 _ DIA. WIRE, RED VARGLASS WITH EPOXYrJ_ / SLEEVING FROM EDGE INSTALL AFTER
/ OF BAR (STRIP SGW-7) THERMAL TEST_AJ/ -- BRAZE SPLICE WITH
\\\ / / WITH ROKIDE /// _, #1
\\\ / A2s" / HTOVERCOAT i ///U_ /
\\t / 10 ="'- :o:o:o-o-_%°_-o-o-o...... °.... °_ .... oo ° o : oO;,o;,op:o:o:o .__.
o oZo_o-_o__ p_o_o;,o;.oz_o.©c _b°^------
I - - ITESTGA_,_s_J_ ,. [I "/ Iwn_COA,- -T-- ,.ERMOCO;_-LE=_PE=,--I
GROUND WIRE _m,; ,_ I '' _ IM/_BARE WIRE COVERED WITH RED V]RGLASS
RES. WELDED TO BA_I_ SIDE 2 '_"
W,=I ..........L-.-
_[ 2 4!5 L ROKIDE HT PRECOAT THERMOCOUPLE LEADS WITH ROKIDE HT OVERCOAT(_ GAGE # " " MErCO 443 PREP. COAT "
(SHADED AREAS)
Figure 7.- Test Bar With Strain Gage And Thermocouple Installation
Bar Gage Bar
Numbers Material Material Precoat Overcoat
01 02 03 04 PdCr IN100 Rokide Rokide
05 PdCr IN100 Roklde Roklde & NICrAI
06 26 PdCr IN100 AI2031Zr02 AI203/Zr02
18 PdCr IN100 Roklde AI203/Zr02
25 PdCr IN100 AI203/Zr02 AI203/Zr02 & NICrAI07 08 09 10 ii 12 PdCr CuZr Rokide Rokide
13 14 15 16 17 BCL-3 IN100 Rokide Rokide
19 20 21 22 23 24 BCL-3 CuZr Rokide Rokide
The AI203/ZrO 2 is a mixture of 96% alumina and 4% zirconla powder flamespray coating intended to provide improved oxidation protection to the PdCr
gages. The NiCrA1 (Metco 443) coating is the same as that of the prep coat and
is also intended to provide oxidation protection.
INSTRUMENTATION OF TEST BARS
The PdCr gages were fabricated by Pratt & Whitney using gage wire provided by
NASA. The BCL-3 gages, with the FeCrA1 ribbon leads attached, were purchasedfrom Batelle-Columbus Labs. All gages were Installed in the Pratt & Whitney
Strain Gage Lab, except for PdCr gages with alumlna/zlrconla overcoat which
were installed by HITEC Products, Inc. The two bars with NICrA1 oxidation-
resistant coating were overcoated at Pratt & Whitney.
TEST PROCEDURE
Apparent strain, drift, gage factor and creep testing were conducted as
described below. At every test point, the strain gage bridge output for eachgage (with both positive and negative excitation) was recorded along with the
two thermocouples, insulatlon resistance and time. Oven temperature, excitation(Sv dc) polarlty and precise bar deflectlon were controlled by the data
acquisition system. The excitation was applied to each gage circuit only when
a measurement was to be made (not continuously).
Avvarent Strain Tes_in_
Data were recorded during at least three heating and cooling cycles on all of
the gages. The first cycle was the heat-treatlng cycle and the heat-treatlng
temperature was higher than that of the other cycles by 22K (40°F) for PdCr
and 28K (50°F) for BCL-3 gages. The heat-treating period was 30 minutes. Data
were recorded at equal time intervals during the temperature cycles.
Drift Testing
Data were recorded during constant temperature periods of i0 hours. Testing at
three different temperatures (five for BCL-3 on IN100) was conducted. Each
drift test was preceded by a heating cycle to the maximum temperature (for
each gage/bar type) and a cooling cycle to the drift temperature. Data were
recorded at equal time intervals during the drift and temperature cycles.
Gage Factor Testing
Data were recorded at room temperature, four intermediate temperatures andmaximum temperature for each gage/bar type. Stabilization time was 30 minutes
at each temperature. The temperature sequence was room, first, second, third,fourth, maximum, fourth, third, second, first, room, maximum, fourth, third,
second, first and room. At each temperature, measurements were made in both
compression and tension using a 0, +, 0, -, 0, +, 0, -, 0 bar deflectlon
sequence (nine readings per sequence producing four compression and four
tension measurements. The deflection sequence was run at both approximately500 and 1000 mlcro-straln. The exact strain level for each deflection was
measured at room temperature using reference (commerclal) foll gages.
8
Creep Tes.tinR
Data were recorded during constant temperature periods of i0 hours, duringwhich a strain level of I000 micro-strain was applied (gage I in tension and
gage 2 in compression). Testing at three different temperatures was conducted.
Each creep test was preceded by a heating cycle to the maximum temperature
(for each gage/bar type) and a cooling cycle to the creep temperature. The
strain was applied at the beginning of the cooling cycle. Data were recorded
at equal time intervals during the creep and temperature cycles.
TEST CIRCUITRY
All gages were connected to a Wheatstone bridge circuit as shown in Figure 8.
The BCL-3 gages required setting R2 = RG for a i:i bridge (because they
have no RC). The temperature compensated PdCr gages required setting
R2+Rc= RG (R2 being approximately 55 Ohms) for a i:i bridge. Use ofother than a i:i bridge ratio results in a more complex bridge sensitivity
factor, as shown in Figure 9, and in lead-reslstance changes not canceling inthe two bridge arms.
- EI
IRt/_ R2
_,_. °Eo°
R3 "_*/
RL
tVt4_R G (Pt)RL (PdCr)
RL
GAGE DESIGNED FOR 1:1 BRIDGE (R 2+R L+R C=R L+R G)
Figure 8.- Bridge Circuit - Temperature Compensation
___, // R8 =R2* RC
FOR A 1:1BPJDGE: RB =I
%
AEo" EI _4_÷_.__
Figure 9.- Bridge Formula
Insulation resistance was measured using the Ohmmeter-type circuit shown in
Figure i0. The gage was switched out of the bridge circuit during this
measurement (switches are not shown in Figure 8). Measurements were made
between each of the two gage leads (in the case of PdCr, leads B and C inFigure 5), and the ground wire attached to the test bar. For each lead, two
measurements were made: one with plus and one with minus polarity (of the 1.5
volt dc supply) and the two averaged.
10 OHMS
RI = _--_ (10)-10 OHMS
Figure i0.- Insulation Resistance Measurement Circuit
l0
SECTION 4.0
TEST PERFORMANCE AND ANALYSIS OF RESULTS
Planned and revised maximum test temperatures are shown below. Maximum
temperature for the PdCr alloy was revised after excessive drift was measured
at II50K and above.
Bar Original Revised
PdCr IN100 1144K (1600°F)
PdCr CuZr 811K (1000°F)
BCL-3 IN100 1144K (1600"F)
BCL-3 CuZr 811K (1000°F)
866K (II00°F)
Apparent strain, drift, gage factor and creep testing were conducted and the
test data were recorded on a Hewlett-Packard microcomputer based data
acquisition system. Data files, containing voltmeter readings, were converted
to ASCII format and transferred to IBM MS-DOS files for import into Lotus 123
(worksheet software). Conversion to engineering units and plotting were done
using Lotus 123. In most cases, the thermal cycles were identified on the
plots by the cycle number and A for heating, B for cooling, HT for heat treat,
DR for drift and CR for creep.
PALLADIUM CHROMIUM GAGES
Maximum test temperatures for each test is shown in Table I.
Avvarent Strain D_a (PdCr)
Apparent strain data for PdCr gages on IN100 bars are shown in Figures Ii and
12. The first tests were conducted on bars 03, 01, 02 and 04 (Figure Ii) to
determine the time and temperature effect on apparent strain. From these
results, the maximum test temperature for PdCr gages was reduced to 866K
(II00"F) from the orlglnally planned I144K (1600"F). Bars 05, 06, 18 and 26
(Figure 12) were then tested within the revised maximum temperature.
Bar 03 (gage 03-1 only) was subjected to 14 temperature cycles to 894K
(1150°F) before and temperature cycles to 873K (III2°F) after a 50-hour soak
at 873K. Before the soak, there was a steady increase in the slope with each
cycle (2 of the 6 plotted). The 50-hour soak resulted in greater resistance
stability but with great loss of temperature compensation. Most data for bar
03 were acquired with a hand-balance strain indicator because the data system
was not ready for use when testing started. Gage 03-2 is not shown because the
analysis was not fully completed, but enough points were analyzed to show that
the trend was the same.
Bar 01 was subjected to one thermal cycle to i023K (1382°F), with a one hour
dwell at I023K and three cycles (only two shown) to 873K (1112°F). The initial
heating cycle is not shown because of a data system malfunction. The dwell at
1023K resulted in good resistance stability but with a large loss of
temperature compensation.
11
TABLE I.- PdCr STRAIN GAGES: TESTS CONDUCTED AND MAXIMUM TEMPERATURES (K)
Bar Bar Heat Apparent Drift Gage Creep
Number Material Treat Strain Factor
01 IN100 1022 853
02 IN100 1023 853 1023
03 IN100 894 894 894 866
04 IN100 894 866 866
05 N IN100 889 866 700
811
06 AZ IN100 889 866
18 R IN100 889 866 700
811
25 R,N IN100 Not Tested
26 AZ IN100 889 866 700811
07 CuZr 822 811
08 CuZr 822 811 700
755
811
09 CuZr 833 811
10 CuZr 833 811
11 CuZr 833 811
12 CuZr 833 811
866
866
811
811
811
297
700
755
866
700
755
811
AZ: Alumlna/Zirconla Precoat and OvercoatR: Roklde Precoat and Alumlna/Zirconla 0vercaot
N: NICrA1 Overcoat
12
70
50
\
!_ ,o--
cv
20
10
PdCr Gage 01-1 Cycles 1B,3A,3B,4A,4BAppowen_ gtmle Ju189 (01_ALL1)
/
/
/0.2 0.4 0.6 0.8 I
Te mpem_ee (K)
+ 1B O _A Z_ 3B X 4A _ 4B
PdCr Gage 01-2 Cycles 1B,3A,3B,4A,4BAppane_ S_m;n JuI89 (01 ALL2)
80
7O
6o
E so--O^
,°c v 30
20v
I0
//
/.:. _ r i
f0
o.2 0.4 o.6 0,8 1(_ousond_)
Temperature (1<)
"t 1B 0 5A Z_ 3B X 4A _ 4B
PdCr Gage 02-1 Cycles 1A,1B,2A,2B,3A,SBAppor_nt Stroin AugB9 (02_All 1}
100!
gO
BO
T70
E
_g___ soEo
_, 3o
2O
10
_P
0.2 0.4 0.6 0.8 1
(_ouso_d=)
Temperoture (K)
[] I A + 1B O 2A & 2B x _ V 3B
PdCr Gage 03-1 Effect of 50 Hrs at 873K
50
E" -50
_ -- 100
.-__ -15o
U_ -200=:
v
-300
-35O
J_
/
40O 600 800
Temperotu_ (K)
r_ Cy{ 1-14 (Before) -_ Cyc 19 & 20 (After)
PdCr Gage 02-2 Cycles 1A, IB,2A,2B,3A,3B_op¢,,-_ S_--;_ ,t, g89 (02_*U.2)
120
110
100
_ go
3O
10
-10=-- 1
0.2 0.4 0.6 0.8 1(T_ouso_ds)
Temperoture (K)
O 1A + I B 0 _J_ _. 2B X 3A _ _B
Figure Ii.- Apparent Strain of PdCr
Strain Gages on IN100 Bars
13
PdCr Gage 04-2 Cycles 1A,1B,2A,2B,3A,3B_por_nt Stm;n Jul 89 (04__L2)
30_
25
"E 2O
8
E lS
r= J
e___ _o!Eo
5E
o
-5
2O0
[] 1A
--10
J
400 600
Tempemtur© (K}
+ 1B O 2A _, 21B ;X 3A V 3B
J
_3 1A
40O 6OO 800
Tempem_re (K)
+ IB 0 2A & 2El X 3_ V 3El
Figure ii.- Continued
14
"E lO
5
un o
\ -5£.
-10£
-15
-20
9
8
7
5
?_ 5r
r 4I=
3
1
0
_ s
F o
I ,o
e_u M -5
_- -10
_ -15v
PdCr Gage 05-1 Cycles 1A/HT/B,2A/B,3A/B&Ol_r_t $tr_;n Jan 90 (05_ALL1)
2O
--2O
--25
j_a'e--_ s-ee-._ a...se_
200 400 E00 800
Tempem_.ure (K)
D IA & IHT + IB O 2A & 2B X 3A V 3B
PdCr Gage 05-2 Cycles IA/HT/B,2A,/B,3A/BAppamrrt Struin Jan gO (05_ALL2)
2O
15
10
5
-5
-10
-15
-20
Tempe mtur_ (K)
r'l 1A & 1t41" + 1B O 2A ,e, 28 x 3A 'e 3B
PdCr Gage 05-2 Cycles 2 & 3Aipparen_ Straln (05_ALT2)
PdCr Gage 06-2 Cycle 1A,1B,2A,2B,3A, SB_por_<t S_oT. _pr go (O6_ALI_)
20
15
10
5
i °-5
-10
-15
-20
PdCr Gage 18-1 Cycle 1A,1B,2A,2B,3A,3BA_or_nt 51tro;n Mar 90 (18_ALL1)
_ _._a.._ _
200 400 600 _00
Tem_ n:rt,ur= (K)
25
20
15
10
-- 0
-5
-10
-15
13 1A + IB 0 2A & 28 X 3A _' 3B
+
20o
t3 IA
40O 600 8OO
Temp=rotur_ (K)
4- 1B O 2A A 2IB X 3_k V 3B
PdCr Gage 18-2 Cycle 1A,1B,2A,2B,3A,3BA_amn_. Strain M=r 90 (18 AL_}
"= _s-..e__;_e...s-
200
Jr
400 600 800
Temperature (K)
O IA + 1_ O 2A & 2B X 3A V 38
Figure 12.- Apparent Strain of PdCr Strain GaEes on INI00 Bars with Oxldatlon
Preventive Overcoat
15
25
20
e_Eo
_ o
PdCr Gage 26-1 Cycle 1A,1B,2A,2B,SA,3BApporen'[ 5t.,"oln Apr 90 (26_ALL1)
--10
--15200
[] IA
8O0 8o0
"le mpe_,"e (K)
_- 1B 0 2A _ 28 X 3A V 38
Figure 12.- Continued
Bar 02 was subjected to one cycle to 1023K (1382°F), with a 16 hour dwell at
1023K, and three cycles to 873K (1112"F). The increased exposure time was
intended to further improve resistance stability, but resulted In a greater
loss of temperature compensation.
Bar 04 was subjected to one cycle to 893K (1148°F), with a one hour dwell and
two cycles to 866K (1100"F). The temperature compensation was much better, but
there was stlll a significant increase in slope on each cycle. The maximum
test temperatures of 886K (II40°F) for the heat treat cycle and 866K (II00"F)
for the apparent strain cycles were established for the other gages/bars of
this type. The heat treat duration was established at 30 minutes.
Bars 05, 06, 18 and 26 incorporated two oxidation resistant schemes as
described In the "Test Specimen Design" of Section 3.0. The apparent strain
results for these bars are shown In Figure 12. On bar 05, a coating of NiCrAl
flame spray was applled over the Rokide overcoat as an oxygen barrier. The
increase in slope on cycles 2 and 3 was slightly less than shown on bar 04
(standard overcoat and same temperature cycles). A typical time vs temperature
plot Is also shown for two cycles of bar 05. Bar 06 was instrumented wlth a
precoat and overcoat of aluminalzlrconia for oxidation resistance (same as bar
26). The increase In slope on cycles 2 and 3 was slightly less than shown on
bar 04 (standard overcoat and same temperature cycles). Because gage 06-1 had
an open circuit after Installation, no data were acquired. Bar 18 was instru-
mented wlth a standard Roklde precoat and an alumina/zirconla overcoat for
oxidation resistance. The Roklde precoat was used because of extreme difflculty
In installing the alumlna/zlrconla precoats on bars 06 and 26. Although the two
gages were identical, gage 18-1 experienced a much greater increase in slope,
on cycles 2 and 3, than gage 18-2. Thls difference has not been explalned. Bar
26 was instrumented wlth a precoat and overcoat of alumina/zirconla for oxida-
tion resistance (same as bar 06). The increase in slope on cycles 2 and 3 was
sllghtly less than shown on bar 04 (standard overcoat and same temperature
cycles).
16
Apparent strain data for PdCr gages on CuZr bars are shown in Figure 13. Bars
07, 08, 09, 10, ii and 12 were all instrumented with the standard Roklde
precoat and overcoat and were subjected to a heat treat cycle to approxlmately833K (1040°F) and two apparent strain cycles to approximately 811K (1000°F).
The heat-treat period was 30 minutes. The exact maximum test temperatures for
each bar are shown in Table I. For bar 07, data from all three cycles for both
gages were lost because of a data system malfunction. Three additional cycles
(4, 5 and 6) were run and data for gage 07-2 are shown. The change in slopewas small, but this stability may be due to the additional cycles run.
However, data from gage 07-i was not properly recorded. For bar 08, data for
cycles 2, 3 and 4 are shown. Data from cycle i were lost because of a recorder
malfunctlon. Cycles 3 and 4 were run after making a slight adjustment of the
temperature compensation circuit to increase the compensation (reduce R2).
On cycle 2, R2 was Inadvertantly set too high (70.1 and 65.8 ohms for gagesi and 2, respectively). Prior to cycles 3 and 4, R 2 was set to the proper
value such that R2+R C = RG (54.2 and 53.3 ohms, respectlvely). Theresults show that the 3.3 ohm compensator is about the correct value for the
58 ohm gage (RG/R C = 17.6). Bar 09 had the lowest (negative) slope of allthe PdCr gages. The increase in slope on cycles 2 and 3 was similar to the
other gages, however. The data from bar I0 shows a premature temperature drop
and recovery on cycle 3A. This additional time at temperature may account for
the slope on cycle 3B being greater than that of the other cycles. On bar ii,
the data of cycle IB were lost because of a data system malfunction. The heat
treat dwell (30 minutes) is plotted so that the end points of cycle IB may be
determined. Bar 12 had near optimum thermal compensation (nearly zero slope).
This happened by chance because the resistances of the gage and compensation
grids cannot be controlled any better than they were in this program.
17
PdCr Gage 08-1 Cycles 2A,2B,3A,3B,4A,4BApparent $'L'11ln 0d¢,_9 (08 ALL1)
16 =
_ ,o
;E
g .2
0
-2
2
o
E -2
E o -6
o:
_e -10
-12
-14
[] 2A
-16
6oo Boo
Tempemtur'= (K)
+ 2B O 3A _ 3E¢ X 4A V 4B
PdCr Gage 09-1 Cycles 1A,1B,2A,2B,3A,3B_ar=nt _-Q;n Dec 8g (09__.1)
6
_=[
20O
O 1A
PdCr Gage 07-2 Cycles 4A,4B,SA,5B,6A,6BAppe,-=_l Strein No_B9 (07J_.A)
ao!
i
!
is
_,oEo 8
;g
_ 4g
-2
r,
Tempenature (K)
[] 4_, + 4B O 5A & 58 X 6A V 68
PdCr Gage 08-2 Cycles 2A,2B,3A,3B,4A,4B• pl_r_t Sb'_in O¢t89 (08 AI-I_)
20
1B
16
14
12
i,o
4
2
0
-2
6
4
2
0
2
4
6
8
0
2
4
62O0
O 1A
w
Y
200 4_3 600 800
Tempem_ne (K)
0 2A + 2B O 3A z_ 3B X 4A V 48
PdCr Gage 09-2 Cycles 1A,1B,2A,2B,3A,3BApparent Stna;n Dec 89 (O9_ALL2)
\
4OO 500 8,OO 400 600 BOO
Tempena_re (K) Temperature (K)
•F" 1B 0 2A & 2B X 3A V 3El 'i" 1B 0 2A A 2B X 3A 1_ _'B
Figure 13.- Apparent Strain of PdCr Strain Gages on CuZr Bars
18
PdCr Gage 10-1 Cycles IA, IB,2A,2B,3A,3BAppore_. S'b'o;n Oc_ 89 (10. ALL1)
16
14
12
'%.
_ 8
I 'o2g s
\ 2
0
-2
-4
I
-6
40O 6O0 800
Temperature (K)
O tA + 1B O 2A & 2B × 3A V 3B
PdCr Gage 11-1 Cycle IA, 1HT,2A,2B,SA,3BAppor_nt Sb_;n May 90 (tl ALL1)
10
6
6 4
+i ou
$
-8
-lO
-122oo 400 600 8OO
Temperoture (K)
g 'IA + IHT O 2A 4 2B X ,SA V 3B
2
8 o
E -2
e _ -4ul, l
--10
-12
--14
-t6
PdCr Gage 12-1 Cycles 1A,1B,2A,2B,3A,3BAppor_"ff. S_;n Moy 90 (12 ALL1)
6
4
'\
D 1A
400 6OO 80O
+ IE O 2A & 2 ¢1 x 3A V
t0
8
6
4
2
-1
-E
£
PdCr Gage 10-2 Cycles 1A, IB,2A,2B,SA,SBApporent _ro;n Oct 89 (IO ALL_)
• 4 t
200
El 1A
4OO 500 8OO
Tempem_Jr_ (K)
+ 1B 0 2A 6 2B X 3A V 3B
PdCr Gage 11-2 Cycle 1A, 1HT,2A,2B,3A,3BApporent Stro;n M_y 90 (11__U-2)
I
200 4O0
1A "1" 1HT
6O0 BOO
T=mpemiure (K)
o 2A & 2B x 3A _ 3B
I
PdCr Gage 12-2 Cycles 1A,1B,2A,2B,SA,3BAppont_t Stlr_in May 90 (12 ALL2)
6
4
2
0
.2
.4
"6
IC --
1|
2OO 4OO 6OO BOO
Te rope mtur_ (K)
1A + 1B O 2A & 2B X _ _ 36
Figure 13.- Continued
19
Drift Data (PdCr)
Drift data for PdCr gages are shown in Figure 14. In each plot, data shown for
approximately the first hour represent the period of cooling from the maximum
temperature to the drift temperature, and the next 10 hours (I through ii) isthe drift test period. Bar 08 was instrumented with the standard Rokide
precoat and overcoat. Bar 05 was instrumented the same as Bar 08 but with the
addition of a coating of flame sprayed NiCrAI. No data were acquired from gage
05-2 at 700K because of a data system malfunction. Bar 18 was instrumented
with a Roklde precoat and alumina/zlrconia overcoat. Bar 26 was instrumented
with both precoat and overcoat of alumina/zlrconia.
The following is a summary of the drift rates (in micro-0hms/0hm per hour).
Bar-Gage Precoat Overcoat 700K 755K 811K
(800°F) (900°F) (1000°F)
08-1 CuZr Rokide Rokide +i00 +100 +600
08-2 CuZr Rokide Rokide +100 +100 +600
05-1 IN100 Rokide Rokide/NiCrA1 +50 - -100
05-2 IN100 Rokide Rokide/NiCrA1 - - -100
18-1 IN100 Roklde A1203/Zr02 +50 - -600
18-2 INIO0 Roklde A1203/Zr02 +50 - +400
26-1 IN100 AI203/Zr02 AI203/Zr02 +I00 - +550
Gage Factor D_ta (PdCr)
Gage factor data for PdCr gages on INI00 bars are shown in Figures 15 and 16
and on CuZr bars in Figure 17. For each gage, the gage factor and gage factor
variation are shown. Each point on the gage factor plot is the mean of the fourmeasurements described in the "Test Procedure" of Section 3.0. The variation
is defined as two times the standard deviation of those four measurements as a
percent of the mean.
Strain levels, measured at room temperature with reference gages, were
repeated at elevated temperature with precise control of bar deflection and
while maintaining uniform temperature over the active bar length of 7.62 cm
(3"). Bar deflection is 5.94 mm (.234 inches) for i000 micro-straln and is
repeatable within ± 13 _m (.5 mil). Bar temperature was held constant within a
17K (30°F) range as determined from a temperature test on a similar bar
several years ago and shown in Figure 18.
The measured gage factor of 1.4 for the Pt compensated PdCr gage was about as
expected from published gage factors of 1.8 for Pd Cr and 4.8 for Pt. A
compensation element with a lower (than Pt) gage factor would desensitize the
PdCr less, but the resistance stability of Pt was worth the sensitivityreduction.
20
+.
£
12
11
_0
9
B
7
6
5
4
3
2
I
0
PdCr Gage 05-1 Cycles 4DR & 5DRDr_t Jan 90 (05 DRT1)
¥
I0 2 4 6 8 10
"_ne (h_)
+. 4DR (700K) X SOR (810l<)
PdCr Gage 08-1 Cycles 5DR, 7DR, 8DROHR. Oct 89 (08_DR1T)
13
8
8_" loT "O
e_
//
3
0
--=-
PdCr Gage 05-2 Cycle 5DRD,"_t Jo_ 90 (05_Din'2)
I0 2 4 6 8
l_me (houm)
× 5OR (810K)
I0
/
I 'o
u
J
i
_ eeet ,_Be_ Hml_'a"
_ --+,-+-I "+-_P_'_! _-_'¢"_ _"
2 4 6
Time (h c,_)
D 50R 700 K + 7OR 755 K
i'
IB 10 12
O 8OR 811 K
PdCr Gage 18-t Cycles 4DR & 5DRDrlf_ A_r go {18 C)RT1)
4 i
0
--2
-3
-4
-5
-5
0 2
_x
4 6 8
T,me (ho_)
10
4
12
PdCr Gage 08-2 Cycles 5DR, 7DR, 8DRDH_ O_t 89 (08 DR2T)
I
I IO
Jj+
_. _,-_u=_ B"_ _'1_
J
._i_ _ _
2 4 6 8 10
"n,,_,+ (hou_)
D 5DR 700 K + 7D_ 755 K O 8DR 811 K
PdCr Gage 18-2 Cycles 4DR & 5DRo,4_ A_- 9o 08_1:_T2)
_;;lim_4 -- --
_2
22 1____
21
20
16
14
_3
,,o0 2 4 6 8 10 12
+ 4om (_o0_<) x 5DR (B_K)
Figure 14.- Drift of PdCr Strain Gages
21
?6xE
11e_Eo
PdCr Gage 26-1 Cycles 4DR & 5DRDr'Tf_ Apt gO (26 DRT1)
23
22 _-
21
20lg _ _r'_" "+'+'_ _-_-_ "k_-t-t _-
17
_60 2 4 6 8 10 12
+ 4DR (TO0_) x 50_' (811K}
Figure 14.- Continued
22
2
1.9 --
1.8
1.7
1.6
g 1.s!
_ 1.4
1.3
1,1
1
2
1.9
1.8
1.7
1.6
_" 1.5
_ 1.4
1.2
1.1
1
2
1.9
1,8
1.7
1.6
1.5
g
1,2
1.1
1
&
0
o C 50O
PdCr Gage 03-1Goge !roctor (03__1)
A"r
o
A0
40O 6OO
TempemLure (K>
+ T 500 0 C 1000 _ T 1000
800
E
&
PdCr Gage 03-1_g= F'acto_ Voriot;on (03_OlrVl)
170
160 -- --
o150 -- &
140
,0
:0 0
0
_0
iO
bO
_Q0
_C
IC
_C
¢200 400
Tempe_4ur= (K)
O C 500 • T 500 0 C 1000 & T 1000
80O
;o
0
PdCr Gage 0.5-2Ooge Foctcw (03_gf2)
0
? $ O T
o oA 0 ¢ +
+ I
2OO
Temperc_Jre (K)
0 C 50(} ÷ T 500 O C 1000 _ T 1000
PdCr Gage 04-1Gage Foct_" (04_OF1)
8O0
2OO
:t +
[3
400 60O
Tempe_,'e (K)
[] C 500 _- T 5OO O C 10OO _ T 1000
I'80O
150
140
130
120
_10
100 --
90
7O
g 4o
2O
10 _
0
&
oo
7O
PdCr Gage 03-2Ooge ro_m.-VoHo_;m'_ (03 Gt'V2)
o+o
0
¢
8,0&
+
= -I+
^ o o ono
t = _oe
I4O0 500
Temperance (K)
0 C 500 + T 500 O C 10OO _ T 1000
PdCr Gage 04-1Oage F'ocbw Vo_o_.;o_ (04 GFV1)
8O0
50 ,, ,
40
+
• o 6
+ O+
o_ 20 Y" _ O
0 o& u+ _ ++
10 rl
" ' !8 "0
200 400 600 800
Tempe_ture (K)
O C 500 + T 500 o C 1000 _ T 1000
+
+
O
Figure 15.- Gage Factor and Varlatlon of PdCr Straln Gages on INIO0 Bars
23
2
1.9
1.8
1+7
.,_ 1.6
_ 1.5
g_ 1,4
1.3
1.2
1,1
1
PdCr Gage 04-2Goge Foct_- (04.G¢2)
0
"t"
400 600
Tempemturl_ (K)
Q C 500 t" T 500 O C 1000 -_ T 1000
8CO
7O
60
5O
_, 20
10
PdCr Gage 04-2Goge rocto_ Valor;on (04_GF'V2)
D O+
D
_. n a÷+
D
+ A _ O&
I. + 8 $+9
200 400 600
Tl_mpem_JPe (K_'
0 C 500 + T 500 0 C 1000 _, T 10,00
6
8CO
Figure 15.- Continued
24
PdCr Gage 05-1Oe?e Factor (05_CIF1)
2
1.9
1.8
1.7
1.6
_ 1.5 --
200 400 _00
Temperature (r)
[3 C 500 + T 500 O C 1000 A T 1000
1.4
1.3
1.2
1.1
1
O
2O0
PdCr Gage 05-1Goge Iroctor Vor{ot;on (05_GF'V1)
0
÷9+
%v D
.... 43
4O0 6OO 80O
Temperature (;')
D C SO0 + T 500 ¢ C 1000 _, T 1000
0 --
u
+
2
1.9
1.8
1.7
._ 1.5
¢- +.5
1.3
1.2
1.1
1
PdCr Gage 05-2Oege rat's:*- (05._0r2)
i I
2,
2:
2q
1,
1
g,
g
PdCr Gage 05-2Gage roc_or Vor{otTon (0S (_¢V2)
4_
++ ÷
o 0
A
o
t o = °|
200 400 600 800 200
Te n'_pe roture (1_
D C500 + TSO0 O C 1000 Z_ TIO00 D C500
400 54)O
Tempen3_ure (F)
+ T 500 O C 10OO A T 1000
2
1.9
1.8
1.7
g_ 1.4
1.2,
1.2
1+1
1
PdCr Gage 18-1Gage F'octo_" (18.0F1)
/
3:
3(
21
2(
2,
2:
2(
H
} +,
2OO
PdCr Gage 18-1Oage /oct, or VoHo_.ion (15 C,F_I)
200 400 500
Ternpemtu_ (K)
C 500 + T 500 O C IG_O A T 1000 13 C 500
÷
O E)
D
O 13
e
,0[3
e
4
o!+
Tempera_ture (K)
+ T 500 O C 1000 A T 1000
I
--+4A
°o
<>
800
Figure 16.- Gage Factor and Variation of PdCr Strain Gages on IN100 Bars with
Oxidation Protective Overcoat
25
2
1.9
1.8
1.7
1.6
1.5
1.4
1.3
u 1.1
1
"_0.9_ 0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
02O0
PdCr Gage 18-2Gage roctc_ (18 Or2)
/
//
/ II
40O
i..
I1
Temperot_ (K)
[] C 500 + T 500 0 C IC00 _ T 1000
2OO
190
180
170
160
150
140 --
130
120
110 --
_ too
} 9o8O
_ 60g so_ 4o
3O
2O
10
0
PdCr Gage 18-2Ooge Foc_or Vor_oUc,_ (18_)
n
I
0 C500 + TSO0
400 600 800
Te,-_l_, mtu_ (K)
o C 1000 _ T 1000
Figure 16.- Continued
26
2
1.9
1,8
1.7
I_ 1.5
g_ 1.4
1.3
1,2
1.1
12oo
2
1.9
1.8
1.7
1.6v
I_ 1.4
1.3
1.2
1.1
1
2O0
1.9 1
1.8
1.7
1.(5u
g_ 1,4 --
1.3 l
1.2
1,1
1
o C 500
PdCr Gage 09-1Gage F'OC_ (O9_GF1)
4OO
A
O +
oo
o o
5O0 800
Tempe,'o_r'e (K)
+ T 500 O C 10OO _ T 1000
PdCr Gage 09-1Cage Factor VoHa_on (O9 GF'I)
4-
2O0
o
t-
o
o
,x
_ mpemtu_ (K)
O C 500 + T 500 O C 1000 zi T 1000
Oi
8OO
PdCr Gage 09-2Ooge factor (09_0r2)
PdCr Gage 09-2Gage Factor Vat;at;on (O9 GFV2)
5
o
5
0
5
o
5
0
o
o
u+ _0 0
400 600 800 200 400 600
Tempe_bJre (K) Temperoture (K)
0 C 500 4- T 500 o C 10OO A T 10OO [3 C 500 + T 500 O C 10OO _ T 1000
8O0
PdCr Bar 10-1Cage Factor (10 Olrl}
b
PdCr Bar 10-1
Gage Fac_.r Vor;oUon (tO_GF_}
0
!
o
4O0 600 800 400 60O
Temperature {K} Temperature {K)
O C 500 4- T 500 O C 1000 ._ T 1OOO O C 500 + • 500 O C 10OO Z_ • 1OOO
8O0
Figure 17.- Gage Factor and Variation of PdCr Strain Gages on CuZr Bars
27
2
1.9
1.8
1.7
1.6
g_ 1.4
1.3
1.2
1,1
1
2
1.g
1.8
1.7
1.5
I_ 1.4
1.2
1,1
1
2
1.9
1.8
1.7
1.6
g
1.2
t.1
1
20O
20O
PdCr Gage 10-2_9e factor (10,_0r2)
Tempero_ur_ (K}
O C 500 ";- T 500 e C 1000 Z_ T 1000
PdCr Gage 11-1Gage Factor (11_.GF1}
ol
4O0 6OO
Temper_ur_ (K)
[] C 500 + T 500 O C 1000 _ T 1000
PdCr Gage 11-2Ooge Iro(:to_ (11._OF'2)
400 600
Ternperoture (K)
[] C 500 + T 500 o C 1000 /1 T 1000
BOO
800
8O0
2,4
22
20
18
16
14
v
b
_ 6
4
B
?
6
5
v
h.
g 2
1
0
4
}
2
I
g
B
_ 613 5
&32
1
0
200
t
o c 5o0
PdCr Gage 10-2Gage Factor VoHo{Lion (10_(]:'V2)
.I
D4- ....
#=
.i-
o •
o=A
6oo
Tem_r=turl (K)
+
O
OO
(3
O
A &
ol800
t" T 500 0 C 1000 ._. T I0(_
PdCr Gage 11-1Oage rocl_r Va6_;e. (11_GP¢1)
2OO
3
+4-
A
D6o
"remi:_rotunB (K)
+
El
o
°!
0 C 500 + T 500 0 C 1000 & T 1000
80O
PdCr Gage 11-2Oage Facto*- VoHotlon (11 OF'V2)
4O0 6OO
"rempemtu_ (K}
8O0
[] C 500 + 1" 500 0 C 1000 A T 1000
Figure 17.- Continued
28
1o
Strain Gage Bar Temperature GradientMo;"_holl F'umace (4--841>
C
E
I-
0
_,o x&-20
/7
-,o / \-50
-60--2 -1 0 I
Locok;o_ From Center (inches>
D 6261:- _t 1038F Q 1324F 6 1516F X 1BOOF 9 181iSF
Figure 18.- Axial Temperature Distribution On A Test Bar
The gage factor results from bar 03 indicated a higher gage factor than from
other PdCr gages (about 1.9 compared to 1.4). This was possibly because of Cr
depletion due to oxidation from long exposure to elevated temperature during
previous apparent strain testing. Addltlonal evidence of this was a gageresistance that decreased from about 60 to 40 Ohms during the apparent strain
testing. Also, it is possible that the Pd diffused to the wire surface,resultlng in electrlcal shunting of the PdCr wire. The gage factor results
from gage 18-2 indicated a continuous reduction in gage factor with time, the
last measurement being near zero. This was due to delamlnatlon of the Roklde
overcoat and loss of the gage bond to the precoat. Results from gages 10-I and
11-2 indicate erratic readings above 533K (500°F). For gage 10-1, the reasonwas not found but could be a recording malfunction or a loose connection in
the circuitry. For gage 11-2, the reason is probably a loose connection in the
gage circuitry (the gage was found to have an open circuit during the post-
test inspection).
Creev Data (PdCr)
Creep data for PdCr gages are shown in Figure 19. In each plot, data shown for
approxlmately the first hour represent the period of coollng from the maximum
temperature to the creep temperature, and the next i0 hours (1 through 11) is
the creep test period. The creep strain of 1DO0 mlcro-strain resulted in about
1400 mlcro-Ohms/Ohm (gage factor is about 1.4) of delta-R/R. Because creep is
the relaxation of strain in the cement and gage, creep must be in the opposite
direction from and no greater than the applled strain. The creep direction
would be minus for gage i and plus for gage 2 because of the bending strain.
The data shows that the drift is too great to measure any creep if it exists.
Except for the 700 and 755K results from gage 12-2, the direction or magnitude
does not fit the creep character.
BCL-3 GAGES
Maximum test temperature for each test is shown in Table II.
29
36
34
32
30
26E
_ _0
g: 18
12
10
8
8
4
2
?
E
_ ..4
g -6
_" -12
_ -14
-16
-18
-20
-22
PdCr Gage 04-1 Cycles 4CR, 5CR, 6CRCreep (÷1000 ue) I_c 89 (04 c_'rl)
_ .,-.,.._..,..,__+v_lk
L
2 .4 6 8
T;me {houma)
4CR (TO0_) ÷ 5CR (755K) o sc_ (86SK)
t"-,."k
PdCr Gage 05-1 Cycle 6CRCreep (.,,.1000 ue) a_ go (06 era'l)
t%_
\
lO t2
0 2 4 6 8 10 12
lnr,_ (hour_)
+ 6CR (_.6K)
Figure 19.- Creep of PdCr Strain Gages
E
._-Eo
g
!
7
xE
£
9
40
38
3_
34
32
5O
28
26
24
22
20
18
'16
14
12 --+
lC
PdCr Gage 04-2 Cycles 4CR, 5CR, 6CRC,'_ep (-lOOe_e) De,: 89 (04 cm'2)
I
J
L
.Jri
2 4. 6 8
I"1 4_1_ (700_) "t- 5CR (755K) 0 eC_t (_66K)
8
_i-4
-6
-8
-10
-12
--14
-15
-18
-20
-22
2O
_8
16
14
12
10
8
6
4
2
0
-2
-4
--8
-10
PdCr Gage 05-2 Cycle 6CRCreep (-_000 _) a_ 90 (oS_Cm'2)
I\
\
0 2
\
\
%
4 6
"_._ (hou,_)
* SCR (essK)
\'-,..
8 10
PdCr Gage 12-2 Cycles 4CR, 5CR, 6C_Cntep (-+000 .e) May go (_2_cm'2)
- l0 2 4 6 B 10
"nine (hou,_)
D 4CR (7_) + 5_ (7554<) O 6_ (811K)
12
i
3O
TABLE II.- BCL-3 STRAIN GAGES:
TESTS CONDUCTED AND MAXIMUM TEMPERATURES (K)
Bar Bar Heat Apparent Drift
Number Material Treat Strain
13 IN100 1172 1144
14 IN100 1172 1144
15 IN100 1172 1144
16 IN100 1172 1144
17 IN100 1172 1144
19 CuZr 839 811
20 CuZr 839 811
616
7O0
755
811
1144
1144
700
755
811
Gage
1144
1144
21 CuZr 833 811 811
22 CuZr 839 811 811
23 CuZr 839 811 811
24 CuZr 839 811
Creep
700
866
1144
700
755
811
Apparent Strain (BCL-3)
Apparent strain data for BCL-3 gages on IN100 bars are shown in Figure 20 and
on CuZr bars In Figure 21. On the first cycle, the bars were subjected to a
heat treat of 50°F above the established maximum test temperature for 30
minutes. Thls is the heat treatment recommended by the gage producer, Batelle-
Columbus Labs.
The results from gages on IN100 bars indicate a large change in slope between
the heat treat and the other two cycles. The second and third cycles are about
the same when the heating and coollng time histories are similar (bar 15, for
example). Tlme vs temperature plots for bars 13 and 15 are shown. Differences
between the second and third cycles are due to longer than planned heating or
cooling times caused by improper oven control (bar 13, for example). Thesedifferences are due to the known tlme/temperature dependency of the resistance
of the FeCrAI famlly of gage alloys. Data from the third cycle of gage 16-1
and from all three cycles of gage 16-2 were lost due to a data system
malfunction. Data from the first cycle, below 900K, from bar 17 were lost
because of an electrical power failure (local circuit breaker).
The results from gages on CuZr bars indicate better uniformity of the three
cycles because of more uniform temperature histories and low drift in the
range of 811K (1000"F).
31
BCL-.3 (;age 1.3-1 Cycle 1A, 1B,2A,2B,3A,3BApporll_ S_u'oin Jon 90 (13 _LL1)
5
0 L
_" -25 _
-35
--400.2 0.4 0.6 0.8 1
(3_ousond_)
Tempemtur_ (K)
0 IA + 1B 0 2A _, 2B X 3A ¢' 38
I1.2
BCL-5 Gage 15-2 Cycle 1A, 1B,2A,2B,3A,3BAp_r_nt Sl_;n ,ion 90 ('t3 /¢1.2)
5
0
I0 -- \
,o15
_0 ......... i_J
55
400,2 0.4 0.6 0.8 1
Cmo,so.d,)
Temperature (K)
O 1A ÷ 1B O _ -'- 2B X 3A 9 3B
1.2
_'_ --10
E
I _ -15
e_Eo
_ -2s
-35
-4O
BCL-3 Gage 14-1 Cycle 1A, 1B,2A,2B,3A,3BAppoint S_ra;n F'llb 90 (14_ALL1)
5.
x
0.2
o 1A
0.4 0.6 0.8 1
_m_ _)
+ IB o _ • 2B x 3A V
1.2
BCL-5 Gage 14-2 Cycle 1A, 1B,2A,2B,3A,3B
O
-5
-10
-15
-20
-25
-30
-35
-40
-45
0.2
\\
%
0.4 0.6 0.8 1
(l'l-,ouson_)
Ternpero_Jn_ (K)
0 IA + 1_ O _A A 2B X _ 9
1.2
--5
-10
8-15
E
; _ -2oEo
Eo
_ -_
-'x 5
-40
-45
BCL-3 Gage 15-1 Cycle 1A, 1B,2A,2B,3A,3B
\
Appclremt Stra;n Jan gO (15 ALLI)
\
%
0.2
[] 1A
0.4 0.6 0.8 1
(Tha.._a.c_)
Tempemtun_ (K)
+ IB O 2A t, _J_ × _ _ 3_
1.2
BCL-3 Gage 15-2 Cycle 1A, 1B,2A,2B,SA,3B_4_poclnt Stro|n Jon 90 (15 NJ-2)
o.s i
oi \
15
_0 --
25 --
N
_5
_0
45
0.2
\
.....
0.4
0 1A + IB O _]k
0.6 0.8 I
(Thouaands)
T,.'._ ratun_ (K)
_. 2B x .3A V 313
1.2
Figure 20.- Apparent Strain of BCL-3 Strain Gages on IN100 Bars
3Z
o
-5
_' -10
-15
c -20
E_ -25
¢ -30
-35
-4O
-45
BCL-3 Gage 16-1Apporlmt. Stro;n rBb 90 (16_ALL1)
\\
X,
Cycles 1A, 1B,2A,2B
0.2 0.4
in 1A
,1
1.2
BCL-3 Gage 17-1 Cycle 1A, 1B,2A,2B,3A,3BApporen_. Strain May go (17_ALL1)
0
--5
"_ --15
_ -2ouo-i
E -25
I[ --30
0 -35v
-4O
\
--45
0.2 0.4 0.6 O.B 1
Te rope m_r_re (K}
[] IA + IB O 2A _, 2B X 3A V 3B
1.2
BCL-,3 Gage 1,3-1 Cycle 1A, 1B,2A,2B,3A,3BAp poPlm_. Stroin (13 ALT1)
t::!28 _26 - _ i_-IB-.6.
_--B,-,I_-- _ _,_e.. -24
22
20
18
16
14
12
10
8
$
4
2
0
0.2 0.4 0.6 0.8
Tempi m_Jnl (K)
O Cycle* I, 2 & 3
= : J
1 1.2
BCL-3 Gage 17-2 Cycle 1A, 1B,2A,2B,3A,SBAppare_L Stroi_ May 90 (17_ALL2)
0
5
0
lC
t_
H
¢(
4_0.2
\%
_, _.
[] IA + 1B
0.4 0.6 0,B I 1.2
T._p_tur_ (K)
o 2A A 2B x 3A v 3B
BCL-3 Gage 15-1 Cycle IA, 1B,2A,2B,3A,3BAppanmt Sb_in (15 ALT1)
=' ] I21 _ "
2(
_ '_.._ ,_ _
0.2 0.4 0.6 0.8 1C_,_,.,J o,_',,)
O Cycle_ 1. 2 & 3
1.2
Figure 20.- Continued
33
,57
,.,._Eo
o
v
57
£
T
g
0
-2
--4
--6
-8
--10
--12
--t4
--16
-18
--20
-22
--24
--26
BCL-3 Gage 19-1 Cycle IA, 1B,2A,2B,3A,3BAplaart._. Stre;n Feb 90 (19 ALL1)
2
%
[3 1A
400 6OO 8OO
T=mperoture (K)
÷ lIB O 2A & 2B X 3A V 38
BCL-5 Gage 19-2 Cycle 1A, IB,2A,2B,SA,SBAppar'e_ S_in Feb go (19 ALL2)
2OO
a_
O 1A + 1B 0 2A
4OO 643O 80O
Temp=mture (K)
z= 2B x 3A V 3B
BCL-3 Gage 20-1 Cycle 1A, 1B,2A,2B,3A,3BApponmt S_mTn Feb 90 (20 ALL1)
2
0
-2
-4
-6
-8
-10
-12
-14
-16
-18
-20
-22
-24
-262O0
rt 1A
BCL-3 Gage 20-2 Cycle 1A, tB,2A,2B,SA,3B_perent S_ol. r,=b 9O (2OJCL2)
2
\%
\
4OO 6O0 8OO 20O 40O 60O 800
TernF_em_r_ (K) Tmmperot_t1_ (K)
+ IB c. _ A 2B X _ V 3B _ D IA ÷ IB 0 _ A 2B X _ V
BCL-3 Gage 21-1 Cycle 1A, 1B,2A,2B,3A,3BAp_amn _. S_.roln Mar gO (21 ALL1)
2
o
-2 _-4
-6 ,%
-- 10 )1-12
,,%.-14 '_1_-
--16 -- --
-1B ' --" '_-_,
-_= _ _--24
--26
[] 1A
BCL-3 Gage 21-2 Cycle 1A, 1B,2A,2B,3A,3BApparent _tra;n Mot 90 (21 ALL2)
2
6
-%
400 1500 800 200 400 600 800
Temperature (K) Tempemtune (K)
+ IB O 2A & 2B X 3_ _' _B [] IA + IB O 2A & 2B X 3A _ 31B
Figure 21.- Apparent Strain Of BCL-3 Strain Gages On CuZr Bars
34
O
-2
6 -s
E -8
8"; -loe_o
_ -_2Ea
;'_ -_,--16
-20
--22
--24
--26
.-_ --4
_6 i
_'_ -_o1 Ioe_
= -12
_ -16
v --20
BCL-3 Gage 22-1 Cycle IA, 1B,2A,2B,3A,3BAp_t S_in Ap" 90 (22_ALL1)
2
%e-_1
?8
Tempem_ (K)
[3 1A + 1B O 2A A 2B X _ V 3B
BCL-3 Gage 23-1 Cycle 1A, 1B,2A,2B,3A,3B_opo_ S_,a;n &at SO (23__L1)
2
o J
--22
-24
-26
\lk
%
"-C _ _ __
0
-2
200 400 600 8OO
Tem pe,"uture (K)
O IA ÷ 1B O 2A & 2B X _ V _B
BCL-3 Gage 24-1 Cycle 1A,1B,2A,2B,3A,SBAppo_t Slro;n _ 90 (24__.L1)
2
--4
-6
_ -loeg_ _ -12
7_
_V
_ --18 --
v --20
--22
--24
--26
[] IA ,I- 1B O 2_ _ 2B X 3A V 36
BCL-3 Gage 22-2 Cycle 1A, 1B,2A,2B,3A,3BAppa,"_t Stro_ Apt 90 (_._. N.I.2)
2
° _.
%,,,,
"%%.
I200 400 600 800
Tempem_ (K)
O IA + 1B O 2A & 2B X 3A _ 3B
BCL-3 Gage 23-2 Cycle 1A, l_,2A,215,,3A,OUAp_t Sb_n AW 90 (23_/_Lt..2)
2
O
i-8
I0 --
12
14
16
18
ZO
Z2
Z4
26
%
g-
Tempem_,_ (K)
O 1A + 1B O _ t_ 2B X 3A _ 3B
BCL-3 Gage 24-2 Cycle IA, IB,2A,2B,$A,_B_opo_t¢_ SL,'ain Ap_ 90 (24_N.I-2)
I
.-._
Temperature (K)
0 1A + 1_ 0 2A t_ 2B X 3A _ .38
Figure 21.- Continued
35
Drift Data (BCL-3)
Data for BCL-3 gages are shown in Figure 22. In each plot, data shown for
approximately the first hour represents the period of cooling from the maximum
temperature to the drift temperature, and the next I0 hours (i through n) is
the drift test period.
The following is a summary of the drift rates (in micro-0hms/0hm per hour).
Bar-Gage Type 616K 700K 755K 811K I144K
(650°F) (80O°F)_ (900°F) (1000"F) (1600eF)
13-1 IN100 +100 -550 -260 -20 -230
13-2 IN100 +100 -550 -260 -20 -220
20-1 CuZr - -410 -5 +40
20-2 CuZr - -420 -5 +30
w
w
Gage Factor Data (_CL-3)
Gage factor data for BCL-3 gages on IN100 bars are shown in Figure 23 and on
CuZr bars in Figure 24. For each gage, the gage factor and gage factor
variation are shown. Each point on the gage factor plot is the mean of the
four measurements described in the "Test Procedure" of Section 3. The
variation is defined as two times the standard deviation of those four
measurements as a percent of the mean.
The results from INIO0 bar 15 indicate a lower than expected measurement and
from IN100 bar 16, a higher than expected measurement of gage factor, based on
the published value of about 2.4 (room temperature). On bar 16, the reference
strain measurement was repeated twice (with new reference gages), but the
excessive measured gage factor was not explained. Simple bend load testing was
conducted in an attempt to varify the results, but the results indicate that
the high measured values are invalid (see Appendix). The measurements could be
due to defects in the cast material. The gage factors of the gages on the CuZr
bars agreed more closely with each other.
Creep Data (BCL-3)
Creep data for BCL-3 gages are shown in Figure 25. In each plot, data shown
for approximately the first hour represents the period of cooling from the
maximum temperature to the creep temperature, and the next i0 hours (I through
ii) is the creep test period. The creep strain of I000 micro-strain resulted
in about 2400 micro-0hms/0hm (gage factor is about 2.4) of _R/R. Because
creep is the relaxation of strain in the cement and gage, creep must be in the
opposite direction from and no greater than the applied strain. The creep
direction would be minus for gage 1 and plus for gage 2 because of the bending
strain.
At all temperatures, the change in AR/R was in the same direction for both
gages i and 2. This indicated that the change was due to drift and not creep.
At 755, 811 and 866K (900, 1000 and II00°F), the change was very small,
indicating that any creep or drift that may be present was very small.
36
-28
"E -2g
-30
_'; -31I '0e=.
. -32
¢" -34
-35
BCL-3 Gage 15-1 Cycles 4, 5, 6, 7 & 80,-[_ Jan 90 (13_0RT_)
-26
-27
-36
-37
-38
-16
-17
-1B
_ -20
g'; -21I 10egv _ -22
¢ --24o
i\ _+"\
I2 4
•+ 7_
6 8 10
"rime (hour_)
O 755K /t 811K X 1144K
BCL-5 Gage 20-1 Cycles 4, 5 & 6_f_ Feb 90 (_ _rl)
12
-25
--26t
--27 _ ----
/--28
0 2 4 6
"nine (hour=)
a 4 (7co,:) + s (';'_K)
-28
-29
-30
-31
E -32
ii -34
-3s
i -36
-3E
-4(
8 10 12 0
BCL-3 Gage 13-2 Cycles 4, 5, 6, 7 & 8_ Jan 90 (13 OR_2)
_,_.
---o tJ_+ I 1_
O 618K
2 4 6 8 10
_m¢ (bout'l)
"1" 70OK O 75_K A 811K X 114.4K
12
BCL-3 Gage 20-2 Cycles 4, 5 & 6c_ r=b90 (2o om_)
-1+1 1--17 !
-,+ ........,....t.....1..l
-26 t-2"/
-282 4 6
"n_e (_,._)
o _ (7oo_) + s (Ts._)
Figure 22.- Drift of BCL-3 Strain Gages
37
3.2
3
2.8
2.6
2.4
_ 2,2
1.6
1.4
1.2
1
3.2
3
2.8
2.6
2.4
"_ 2.2
g 28
1,8
1.6
1,4
1.2
1
3.2
3
2.8
2.6
2.4
u 2.2
1.8
1.6
1.4
1.2
1
0.2
0,2
BCL-3 Gage 15-1Cage Fact,or (15,_Olrl)
BCL-3 Gage 15-1Oage roch3r Vor{oUo_ (15_OFV1)
!
Ib
0.4 0.6 0.8
[3 C500 + TS00 0 C 1000 6 T 1000
t
v
1.2 0.2
t"
O
&
v
8
o
m Ao
g
J3
0
4-
0
D
0
0.4 0.6 0.B 1
(_ouson_)Temperature (K)
O C 500 + T 500 O C 1000 A T 1000
0.2
BCL-,3 Gage 15-2Oage FQctor (15_or2)
.t-
0.4 0,6 O.B 1
Tempem_'l (K)
0 C 500 I" T 500 O C 1000 -_ T 1000
BCL-5 Gage 16-1Gnge Foctor (16 OF1)
L°°
• 1-
I0.4 0.6 O.B !
(_sands)Tem pe m_oJrl_ (K)
O C 500 + T 500 O C 1000 & T 1000
f,
5
2
1.2 0.2 0.4
BCL-3 Gage 15-2Gage Factor Vo_ot'c,n (15_GFV2)
D
%o
o
oA
o _' to
•I- A
[] •4-
÷4,
0.2 0.4 0.6 0.8
C500 + T _0 0 CI000 _ TIO00
BCL-5 Gage 16-1Ooge Foctor VaHatlo_ (16 OF'V1)
0
4,
+
0.6 O.B
(lV, c_.a_as)Tempe n_u_ (K)
O C50_ ÷ TS00
Ao{4-
O
0
A
Ao
o
0
¢ C 1000 & T 10oo
Figure 23.- Gage Factor and Variation of BCL-3 Strain Gages on INI00 Bars
o 5÷
+
1.2
÷
G
1.2
D
38
28
2.4
_. 2'2
1.e!
1.6
1.4
1.2
1
3.2
3
2.8
2+6
2.4
. 2.2
g 2
1.8
1.6
1.4
1.2
1
3.2
3
2.6
2.4
_ 2.2
g 2
1.8
1.6
1.4
1.2
1
0.2
0.2
0.2
BCL-3 Gage 16-2Go8e Irec_ (16,_0r2)
I,-i
%
I,
0.6 0.8 1
Temperature (K)
÷ T 500 O C 1000 6 T _000
BCL-3 Gage 17-1Gage F'octoe (17._GF'1)
t1.2
I
0.4 0.6 0.8 1
TempembJre {K)
D C 500 ÷ T 500 O C 1000 _, T 1000
BCL-5 Gage 17-2,"-,',ge roctor (17_0F2)
t
0,4 0.6 0.8 1
Tempera_uee (K)
D C 500 + T 500 0 C 1000 _ T 1000
1.2
10
9
8
7
6
_ 5
! +
1
O
0,2
0.2
BCL-5 Gage 16-2Gage factor VoHatio. (16_C_V2)
o
om _
o
.+.
+¢
c
+_
.k
0.4 0.6 O.B_n'_ot._ond s)
Tempe,'otu_ (K)
0 C 500 + T 500 0 C 1000 _ T 1000
BCL-3 Gage 17-1Ooge Facto+" VoHot;on (17_GFV1)
rl
, I
°° 11_--
1.2
0.2
9
4D ÷
#
¢
[]
13 el .I. +
_ o
o., o._ o._ _ _._('_.o,,a.)
D C 500 + T 500 0 C 1000 _ T 1000
BCL-3 Gage 17-2Oage Factor Varlet;on (17 GFV2)
O
,o
o
J_s +
+i +
,-t
0.4 0.6 0.8 1C'_oosa-_)
Te,",npe,'atu _ (K)
[3 C 500 + T 500 O C 1000 _, T tO00
[3
D
[]
++^
Figure 23.- Continued
39
BCL-3 Gage 21-I BCL-3 Gage 21-IOoge Factor (21._0_'I) Gage roc_r Valor;on (21 Of"V1)
3.2
3
2.B i
2+6
2.4
_ 2.2
_ 28
1.8
A
u m
1,4
÷ []
1.2 - t-
0+2 0.4 0.6 0.8 1
C_ou,,,d,)
Temperature (K)
[] C 500 + T 500 O C 1000 Z_ T 1000
1.2
50
35
3O
A
;_ 20
0.2
A +
o
0
o _
÷ &+
0.4 0.6 O.B
(l_o_ond=}
Te r_pem_wre (K)
[] CS(X) + TSOO O C1000 & T1000
1.2
3.2
3
2.8
2.6
2.4
2.2?.
g 2
1.8
1.6
t.4
1.0
1
3.2
3
2.8
2.6
2.4
u 2.2
g 2
1.8
!i
1.6+
1,4
1.2
1
BCL-3 Gage 21-2Goge F'octo_ (21_Gr2)
0.2
o j q
+
+
0.4 0.6 0.8 1
('mou=ond=)Temperature (K)
O C 500 + T 500 O C 1000 _, T 1000
BCL-3 Gage 22-IGag= Foct,_r (22.0F'I)
0.2
+
t.2
o
I-
o ; ""At
u
0.6 0.8(Thousand/)
"Tem_m_.ure (K)
÷ T500
z--
00.2
4(
3_
2_
g +
BCL-3 Gage 21-2Gage racer V=Hotio_ (21 OFV2)
_0
A
+O
! o@ @
0.4 0.6 0.8 1
Cn_ov=on_)Tempe_otur= (K)
(3 C5OO + TSOO O C1000 _ TIOOO
BCL-3 Gage 22-IGoge F'octor VoHot_ (22 C#'V1)
[
o
++
A
o
0.4
@
+ 6o
@
+1@
O+6
+
÷
O
I+* le
/,
0.8 10.4 I 1.2 0.2
13 C 500 O C 1000 & T 1000 n C 500 + T 5OO O C 10OO & T 1000
1.2
1.2
Figure 24.- Gage Factor and Variation of BCL-3 Strain Gages on CuZr Bars
40
,3.2
3
2.8
2.6
2.4
_ 2.2
g 2
1,8
1.6
1.4
L2
1
3.2
3
2.8
2.5
2.4
_u 2,2
_ 2
1.8
1.6
1.4
1.2
1
2.8
2.6
2.4
_ 2.2
g 2
1.8
1.6
1.4
1.2
1
0.2
0,2
0.2
1-
BCL-3 Gage 22-2age [ocl_* (22 at2)
i i
+> I iQ t.
I
ID
1
0,4 0.5 0.8
Ci>,ou.a,,.,d.)
Tempera'tyre (K)
[_ C 500 + T 500 o C 1000 A T 1000
BCL-3 Gage 23-1Goge F'octor (23._GF1)
; i I+,i
0.4 0.6 0.8
(Thougondl)
Te_peroture (_<)
q1
D C 500 + T 500 0 C 1000 /Z T 1000
BCL-3 Gage 25-2Gage Foct_" (23_0r2)
, i
0.4
I_0
D
|
+
+
0.6
i
+
o
Ka<>°1
0.8 1
Temperature (K)
a C 500 + T 500 o C tO00 .'- T tO00
1,2
1.2
1.2
40
35
30
25
!'+
5
0
0.2
5(
4(
3!
3<
g
40
35
30
25
_" 2o
5
i o
BCL-3 Gage 22-2Goge Fac_o_ Vor;a6on (22_GrV2)
÷Q
6 -t-
0.4
O C 5O0
0.6 O B 1
Tempe,_ (K)
+ T 500 0 C 1000 Z_ T 10C_
BCL-3 Gage 23-1Gage Foctor VaHat_n (23 GFV1)
r_ u
1.2
÷
0.2
io
o + " Im
I_ + + i
0.4 0.6 0.8
Temperclture (K)
[] C 500 t- T 500 0 C 1000 _ T 1000
BCL-5 Cage 2,5-2Gage Factor Vo_at_on (23_GF'V2)
1.2
g0,2 0.4
C 5O0
^ L_
J_
+
0.6
t
0.8
(l_oulond=l}
TernperO_re (K)
+ T 500 0 C 1000 _, T 1000
1.2
Figure 24.- Continued
41
-44
-46
--48
.; -soI I=E o= -s:
o_-6,;'_ -GG_" -.68
-80
0-.--62
BCL-3 Goge 16-1 Cycles 4CR, 5CR & 6CRCreep (+1000 ue) Mar 90 (1G CRT1)
-38 /
--42 ._
/
-64
-6G
-68
--4
-6
?8 -8_" --10
_._ -+2
E o -16
;_ -,6_" -=o
a -22
--24
-26
-28
0 2 4 6 8 10 12
"nine (ho_)
O 4CR {70OK) ÷ 5CR (866K) o 6CR (114-4K)
BCL-3 Guge 21-1 Cycles 4CR, 5CR & 6CRCreep (+1000 ue) Mot gO (21 CRTI)
I l
.... i .... • .....
2 4 6 8
"nine (h_nl)
o 4CR (70OK) , 5OR (76.SK) ¢ 6cm (81_K)
lO 12
BCL-3 Guge 16-2 Cycles 4CR, 5CR & 6CRCroup (-1000 ue) Mot 90 (16_CRT2)
/
]
Bs
_BB U
o 2 4 6 6 10 12
rl 4CR (70OK) + 8C_ (866K) O 6CR (1144K)
BCL-3 Goge 21-2 Cycles 4CR, 5CR & 6CRCreep (--1000 ue) Mot 90 (21_¢RT2)
0
-2
-4
-6
--8
-10
-12
i -14-16
--1a
-20
_ -,__ --24
-2g
-26
..... :::::::::::::::::::::::
0 2 4 8 8 10
n,,'ne (hour)
0 4C_ (70OK} + 8CR (758K) O 6CR (81 tK)
4
t
BCL-3 Bur 16 Creep Diff.1000 u--stroifl (Re_O--Re=l)/2 (16 CRO)
3.2
3.1
_ 2.9
f_1 2.8
_ _
'o-_ _.4
2+3 --
_ 2.2
2.1 @,_
20
o 4c:R (_'oo_)
ti+;_:
4 6 6 10 12
+ 5cR (866K) o 6C.S_(1144K)
BCL-5 Bor 21 Creep Diff._000 u-_rU'o;n (R,,_--R_)/2 (2LC_O)
-0.82 I I
-0.88 ....
-0.9
-0.96 _
-0.98 -- -- 'XBI _
-'-I.04 --'--
-_Jo6 -" -_P'_ _,-H_-- 1,08
--1.1 I
--1.12
--1.t4
-1.150 2 4 6 B 10
1;m_ (ho_)
[] 4CR (700K) "+ 5CR (756K) ,0 6C_ (811K)
Figure 25.- Creep of BCL-3 Strain Gages
42
Some additional analysis was performed on data from bars on which both gageswere functional. If the drift character was the same on both gages, the drift
and creep would be separable because the strains are equal and opposite.
Therefore, the creep would be found from half of the difference of the signals
(and the drift from half of the sum). This type of analysis was done for BCL-3bars 16 and 21. (The PdCr gages with high drift did not have good enough
uniformity to obtain meaningful results.) The BCL-3 gages did have good
uniformity and the results indicated very low (less than 5 micro-0hms/0hm per
hour) creep. The results of this differential analysis for bars 16 and 21 are
shown in Figure 25.
COMPARISON OF RESULTS
Comparison of PdCr to BCL-3 on IN100
Apparent strain of PdCr is less than that of BCL-3 up to the temperature limit
of PdCr, 866K (II00°F). Above that temperature, BCL-3 has better apparent
strain stability, probably due to better oxidation resistance. Drift of PdCr
is less than that of BCL-3, but they cannot be compared above SilK (1000°F),
the maximum drift-test temperature for PdCr. Gage factor of PdCr is less than
that of BCL-3 (1.4 vs 2.4), because of slightly lower strain sensitivity of
the PdCE wire and the desensitization caused by the platinum temperature
compensation element. Creep of the two gage types can not be compared because,
for the PdCr, drift hides any creep that may be present. Creep of BCL-3 is
very small.
Comparison of PdCr to BCL-3 on CuZr
Comparison may be made only up to the temperature limit of the CuZr substrate,
811K (1000°F). Apparent strain of PdCr is less than that of the BCL-3. Drift
of PdCr is less than that of BCL-3. Gage factor and creep comparisons are the
same as for IN100, above.
ComDarlson of INI00 to CuZr for PdCr
Apparent strain, drift and gage factor results for PdCr were similar for IN100
and CuZr. Creep results can not be compared because drift hides any creep that
may be present.
Comparison of IN100 to CuZr for BCL-3
Apparent strain and apparent strain stability were greater for INI00, due to
the higher maximum test temperature, I144K (1600"F) vs SilK (1000°F). Thermal
expansion accounts for only a small fraction of the apparent strain.
Differences due to the slightly higher temperature-coefflclent-of-expansion of
CuZr would not be noticeable. Drift results were similar for the two substrates
at the same temperatures. Gage factor consistency, gage to gage, was better
for CuZr. However, variation among the four readings for individual gages
(gage factor variation plots) was worse for CuZr. This was thought to possibly
be related to yield of the CuZr bar, but no evidence of yield was found.
Review of the material properties (from Nippert) indicates that the yield
strain is higher than I000 mlcro-straln, even at SilK (1000°F). Also, the
strain measurements, made during gage factor testing, were compared to
determine if the first deflection differed from subsequent deflections. No
differences were found. The large gage factor variation has not been explalned.
Creep was very low for both substrates.
43
INSULATION RESISTANCE DATA
During testing, insulation resistance was measured for each gage at each data
point. These data were plotted for selected apparent strain cycles of PdCr bar
06 and BCL-3 bars 15, 17 and 24. The results indicate that the insulation
resistance drops below i megohm at about 900K (II61°F). This is shown for bar
17 (BCL-3 on INI00) In Figure 26. The results for the alumlnalzlrconla powder
mix were similar to Rokide up to 866K (II00°F), the maximum temperature for
those bars. The measurement method inherently provided better accuracy at low
resistance levels than at high. This accounted for the scatter at low
temperature (and high resistance).
1000
BCL-3 Gages 17-1 & 2 Cycle 2A (Heating)
Insulation Resistance May 90 (17_2ARI)
insulation Resistance (kOhms)100000
1o0oo a I
L
100 _ -- .--___T
10300 400 500 e00 700 coo 900 1000 1100 1200.
Temperature (K)
Gage 1 _ Gage 2
BCL-3 Gages 17-1 & 2 Cycle 2B (Cooling)Insulation Resistance May 90 (17_2BRI)
insulation Realalanoe (kOhma)
k r--l
300 400 500 600 700 800
..-.
l900 1000 1100 1200
Temperature (K)
-- Gage 1 _ Gage 2
Figure 26.- Insulation Resistance
44
THERMO-ELECTRICITY DATA
Thermo-electricity was measured at each data point by measuring the bridge
signal with both positive and negative excitation. This was calculated in the
same way as the resistance change ( -R/R) except that the signal difference
(rather than the sum) was used. The units represent the equivalent -R/Rindicated by the bridge signal due to thermo-electricity. This parameter was
plotted for selected apparent strain cycles for PdCr bar 05 and BCL-3 bars 17and 24. The thermo-electricity range during heating and cooling cycles are asfollows:
T'yDe Cycle Range (mlcro-0hms/0hm)
PdCr Heating 30
PdCr Cooling 30
BCL-3 Heating 270
BCL-3 Cooling 120
The amount of thermo-electrlclty depend on the type of grid and lead wire and
on the temperature gradient along the path. It is generally less during
cooling cycles than heating cycles because cooling cycle are slower and the
gradients less. Results are shown in Figure 27.
POST-TEST INSPECTION
For each test bar, gage circuit and insulation resistance were measured and
the installation was visually examined for defects. Of the 26 tested PdCr
gages, five were found to have an open circuit. All open circuits were located
at the weld of the Pt grid to the noncommon lead wire. Of the 22 tested BCL-3
gages, one was found to have an open circuit. It was located near the center
of the grid. All gages were found to have insulation resistance greater than
20 megohms except for two gages with about one megohm. The general appearance
of the precoats and overcoats was excellent. Only one gage had evidence of
overcoat delamlnatlon.
Resistance measurements of all the gages and compensation elements were made
after testing and compared to those made prior to testing. The results are
shown in Figure 28.
Two additional tests were conducted to determine the thermal stability of the
gage connection box and the self-heatlng character of the gages. In the first
test, with gages connected to the system, the connection box was heated to
measure any output caused by temperature change of the bridge resistors. The
box was heated over a range of IIK (20"F) and the output was small (about 200
micro-0hms per Ohm) compared to the thermal performance of the gages, but
significant relative to strain measurement accuracy objectives. The results
are shown in Figure 29. In the second, with PdCr gages connected to the
system, output was recorded with several levels of excitation to determine the
shift due to gage heating. The results are shown in Figure 30. The two data
points at each excitation level were recorded about 80 seconds apart. At the
5-volt level used in this program, the self-heating effect was small (about 20
mlcro-0hms/Ohm). The power density of the gages as used in this program was
considered acceptable (about .76 watts per square inch for BCL-3 and 1.16
watts per square inch for PdCr).
45
tO
"E" -10
oC
_1 -20
oL.¥E
-30
-4O
PdCr Gages 05-1 & 2 Cycle 2A (Heating)
-5O
#
jv200 400 600 800
Temperature (K)
D Gage 1 + Gage 2
-5O
IN i00
PdCr Gages 05-1 & 2 Cycle 2B (Cooling)Tl_ermo--elec{r;ci{y Jan gO (05_2B't'E)
5OO 50O 7O0
Temperature (K)
Q Gage 1 + Gage 2
gag
BCL-5 Gages 17-1 & 2 Cycle 2A (Heating)_em'no--elec{r;c}{y May 90 (17_2ATD
f
_q
/
0.3 0.5 0.7 0.9 1.1
(_,o,d,_
Tempen_ure (K)
O Gage I + Gage 2
140
120
100
8O
60
"E 4o
{ 2oF o
_ -20
.V --40Ev
-so-80
--120
--140
--180
m
F
J
BCL-3 Gages 24-1 & 2 Cycle 2A (Heating)Thermo--elect_clty Apt 90 (24_2AT_
180
180
} ,°
20 _
_ -20
-40
--6O
-8O
-100
\\
500
TempembJR (K)
ID Ooge 1 + Ooge 2
7OO
BCL-5 Gages 17-1 & 2 Cycle 2B (Cooling)"rt_o--,.ech4c&y I_oy 90 (11 2B1"£)
I
k_, /P
-120
-140
-1600.3 0.5
140
120
100
80
-- 60
"_ 4o
_ ,o
_ °-- Io -20
._ -40
_ -60
-80
-$00
IN i00
{
Z
900
CuZr
%
0,7
C_o_,o.d,)TempemhJre (K)
O Ooge 1 + Gage 2
0.9 1.1
i
9OO
Figure 27.- Thermo-electricity
46
70
Resistance Change of PdCr GagesPdOr [$m-n eft|
uu
1+
60
5O
40
30
20
10
0
:[
-' "_L_L_L_' _ .... L '_ ....o,o_b_r_h_rg_r_;k,110,,_ 1_ ,t,o,t,,11,2',b. 1_,+1_+'11206-207-20e-20g-210-21 I-212-218-2_-226-2
Bor and Cage Humber
Resistance Change of PdCr GagesI_ Element
o1'--11o2'-110g-01-202-203-204-205-206-207-208-209-210-211-212-218-225-228--2
Bor oncl Gage Number
I_ Pr_-_,t _ Po,_--_s*
130
120
110 !
I00
90
80
70
SO
50
40
30
20
10
0
Resistance Change of BCL-5 GagesBy Bor--l_gm
" " L ' _ L " " ' _ --1_111+ ills 111_-11_ 1119 1t_o-11_1 1122 112s-112, ,I,_-2 1,-2 1.s-2 is-2 1+'-_ 1+-2 _-2 21-2 ,,-2 m._-_2,-2
_Ot omd Goge N,Mn_N_P
Figure 28.- Strain Gage Resistance Before and After Testing
47
Connection Box StabilityEqui_nl_nt Apporw_t St,,l_;n (THERMC)
--100
-15o _-\
7 -2ce __...
"_ -250 _,
._ -20 "-. --__..._.___ _ _v
Do -400 _ _ "-,-
--4,.5O ,- _
--500
298 300 302 _1 306 308
Tem_t_ mt_r_ (k)
0 Gage t + Gage 2
310
Figure 29.- Strain Gage Zero Shift from Heating due to Excitation
?
E
E
&
s
-120
- 130
-140
-150
-160
-170
-180
-t90
-200
-210
-220
-230
-240
-250
-260
-270
-280
-290
-300
-310
-320
i _ ¢
Self Heating from ExcitationIEqu_atent Apl_t Sb'oin 014ERMO)
la3
B
B
¢
3 5
E_cR_.;o_ (v de)
Gage I + Gage 2
7 9
Figure 30.- Bridge Completion Network Thermal Stability
48
SECTION 5.0
CONCLUSIONS
PdCr GAGES
O Exposure to temperatures above 866K (II00°F) resulted in an increase in
the temperature-coefflclent-of-reslstance (TCR), probably due to
selective oxidation of the Cr.
Pt is an effective thermal compensation material. The resistance ratio
of PdCr to Pt should be about 18:1. This will allow a bridge ratio of
i:i and provide compensation for thermal resistance change in the leads.
o The drift rate was reduced by adding a NiCrAI coating to the Rokide
overcoat. Use of flame spray AI203/ZrO 2 overcoat did not reduce
drift rate significantly within the limits of this program.
BCL-3 GAGES
o Resistance stability is good above 800K (981°F). For measurement between
800 and I144K (981 and 1600"F), BCL-3 can be a useful gage wire.
Drift is high in the temperature range of 700 to 755K (800 to 900°F).
This results in tlme-dependent apparent-strain character, similar to
other FeCrAI strain gage alloys.
GENERAL
o Insulation resistance is less than one megohm above 900K (II61°F). This
agrees with other experience with Rokide.
o Thermo-electric effect for both gage/lead combinations is low, but that
of PdCr is less than BCL-3.
6.0 REFERENCES
i. Hulse, C. 0., Bailey, R. S. and Lemkey, F. D., "High Temperature Static
Strain Gage Development Program", R85-915952-13, United Technologies
Research Center, NASA Contract NAS3-23169, March, 1985.
2. Lemcoe, M. M., "Development of Electrical Resistance Strain Gage System
for Use to 2000°F '', Paper 75-572 Instrument Society of America, 1975.
49
APPENDIX
ATTEMPTED GAGE FACTOR VERIFICATION OF BAR 16 (BCL-3 ON IN100)
Because the gage factor measurements are higher than expected (approximately
3.0 rather than the publlshed 2.4), slmple room temperature bend load tests
were conducted on bars 15, 16 and 17 in an attempt to verify the measurements.However, the high measurements were not substantiated by these tests and are
probably invalid (although not explained).
The bars were clamped in a fixture and vise and a 27 pound weight was hung on
the other end while measurements were made with a portable strain indicator.
Reference gages were not used because in this loading mode, strain is not
constant along the length (and would be lower at the reference gage location).
Therefore, the exact strain of the bar was not measured, but the relativesensitivity of the five gages was determined. These measurements were made for
gages 15-1, 16-1, 16-2_ 17-i and 17-2 (gage 15-2 was found to have on opencircuit at the end of the scheduled test program). All the measurements were
referenced to gage 15-1 (ratios of sensitivities of the other gage to that of
gaze 15-1 were calculated). Similar ratios were calculated for the origlnalgage factor data for these gages.
The results, shown in Figure A-I, indicate that the sensitivities of all of
these gages are within about 20% of that of gage 15-1. The original gagefactor data indicates that gages 16-I and 16-2 have sensitivities about 60%higher than gage 15-1.
1.7
Bors 15. 16 & 17
O
D-p
+
0
o
r_
b-
I;oio
O
1.6
1.5
1.4
1.3
1.2
1.1
1 "=
0.9
<>
A
A
+
m
<)
o
0.8 I I I I I
15-1 16-1 16-2 17-1 17-2
Bor-Goge
O 0Hg_nol Comp. + 0Hg_nol Ten. o Vorlflcot;on Comp. d Vor_cation Ten.
Figure AI.- Gage Factor Verification Test Data for BCL-3 Gages on IN100 Bars
at Room Temperature. Ratio of Sensitivities of Gages are Relativeto that of Gage 15-i
50
1.REPORT NO. 2. GOVERNMENT ACCESSION NO. 3.RECIPIENT'S CATALOG NO.
NASA CR -189101
4.TITLE AND SUBTITLE
High Temperature Strain Gage for Hypersonic AircraftDevelopment Applications
7.AUTHOR(S)
W. L. Anderson and H. P. Grant
9.PERFORMING ORGANIZATION NAME AND ADDRESS
IUNITED TECHNOLOGIES CORPORATION
iPratt & Whitney
Commercial Engine Business
12. SPONSORING AGENCY NAME AND ADDRESS
Natlonal Aeronautics and Space Administration
Lewis Research Center
21000 Brookpark Road, Cleveland, Ohio 44135
5. REPORT DATE
February 1992
6. PERFORMING ORG. CODE
8. PERFORMING ORG. REPT. NO.
PWA 6141
i0. WORK UNIT NO.
Ii. CONTRACT OR GRANT NO.
NAS3-25410
13.TYPE REPT / PERIOD COVERED
Contractor Report
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
Dr. Mary Zeller, Project Manager, NASA Lewis Research Center, Cleveland, Ohio
44135
16. ABSTRACT
An experimental evaluation of Pd13% Cr and of BCL-3 alloy wire strain gages wasconducted on IN100 and Cu .15% Zr alloy substrates. Testing included apparent strain,
drift, gage factor and creep. Maximum test temperature was I144K (1600"F). The PdCr
gages incorporated Pt temperature-compensatlon elements. The PdCr gages were found to
have good resistance stablllty below 866K (II00°F). The BCL-3 gages were found to havegood resistance stabillty above 800K (981"F), but high drift around 700K (800"F).
17. KEY WORDS (SUGGESTED BY AUTHOR(S)
Strain Gages, PdCr Gages, BCL-3 Gages,
Apparent Strain, Drift, Gage Factor,
Creep
18. DISTRIBUTION STATEMENT
19. SECURITY CLASS THIS (REPT) 20. SECURITY CLASS THIS (PAGE)
Unclassified22. PRICE *Unclassified 21. NO. PGS
51