ASTM E1237-93(2009)
(Guide)Standard Guide for Installing Bonded Resistance Strain Gages
Standard Guide for Installing Bonded Resistance Strain Gages
SIGNIFICANCE AND USE
Methods and procedures used in installing bonded resistance strain gages can have significant effects upon the performance of those sensors. Optimum and reproducible detection of surface deformation requires appropriate and consistent surface preparation, mounting procedures, and verification techniques.
SCOPE
1.1 This guide provides guidelines for installing bonded resistance strain gages. It is not intended to be used for bulk or diffused semiconductor gages. This document pertains only to adhesively bonded strain gages.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:E1237 −93(Reapproved2009)
Standard Guide for
Installing Bonded Resistance Strain Gages
This standard is issued under the fixed designation E1237; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope measurement of small changes of resistance produced by a
strain gage, where the gages may be wired in the following
1.1 This guide provides guidelines for installing bonded
configuration (see also Fig. 1 and Fig. 2):
resistance strain gages. It is not intended to be used for bulk or
Arm 1 between + excitation and − signal
diffused semiconductor gages. This document pertains only to
Arm 2 between − excitation and − signal
adhesively bonded strain gages.
Arm 3 between + signal and − excitation
Arm 4 between + signal and + excitation
1.2 The values stated in inch-pound units are to be regarded
3.2 Definitions of Terms Specific to This Standard:
as standard. The values given in parentheses are mathematical
3.2.1 bonded resistance strain gage—a resistive element
conversions to SI units that are provided for information only
with a carrier that is attached by bonding to the base material
and are not considered standard.
so that the resistance of the element will vary as the surface of
1.3 This standard does not purport to address all of the
the base material to which it is attached is deformed. (For a
safety concerns, if any, associated with its use. It is the
complete definition of this term see Test Methods E251.)
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Significance and Use
bility of regulatory limitations prior to use.
4.1 Methods and procedures used in installing bonded
resistance strain gages can have significant effects upon the
2. Referenced Documents
performance of those sensors. Optimum and reproducible
2.1 ASTM Standards:
detection of surface deformation requires appropriate and
E251 Test Methods for Performance Characteristics of Me-
consistent surface preparation, mounting procedures, and veri-
tallic Bonded Resistance Strain Gauges
fication techniques.
2.2 Other Standards:
5. Gage Selection
ANSI/SEM 1-1984; Standard for Portable Strain-Indicating
Instruments—Designation of Strain Gage Bridge and
5.1 Careful consideration must be given to the intended use
Color Code of Terminal Connections; August 16, 1984.
when selecting an appropriate gage. Installation and operating
characteristics of a gage are affected by many factors such as
3. Terminology
resistive element alloy, carrier material, gage length, gage and
resistive element pattern, solder tab type and configuration,
3.1 Definitions:
temperature compensation characteristics, resistance of active
3.1.1 lead wire—an electrical conductor used to connect a
elements, gage factor, and options desired.
sensor to its instrumentation.
3.1.2 resistance strain gage bridge—a common 5.2 Factors that should also be considered include type of
Wheatsone bridge made up of strain gages used for the test or application, operating temperature range, environmental
conditions, accuracy requirements, stability, maximum
elongation, test conditions (static or dynamic) and duration,
This guide is under the jurisdiction of ASTM Committee E28 on Mechanical
and simplicity and ease of installation. Dissipation of self-
Testing and is the direct responsibility of Subcommittee E28.01 on Calibration of
generated heat to the carrier should be considered in selecting
Mechanical Testing Machines and Apparatus.
Current edition approved April 1, 2009. Published September 2009. Originally gage resistance and size of grid.
approved in 1993. Last previous edition approved in 2003 as E1237 – 93 (2003).
5.3 To minimize errors due to strain gradients over the gage
DOI: 10.1520/E1237-93R09.
area, gage size should normally be small with respect to the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
dimensions of an immediately adjacent geometric irregularity
Standards volume information, refer to the standard’s Document Summary page on
(hole, fillet, etc.). However, the gage size should generally be
the ASTM website.
large relative to the underlying material structure (grain size,
Available from American National Standards Institute, 11 W. 42nd St., 13th
floor, New York, NY 10036. fabric-reinforced composite weave pattern, etc.).
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E1237−93(2009)
7. Surface Preparation
7.1 The surface must be properly prepared to ensure good
bonding. Surface preparation includes solvent degreasing,
cleaning, mechanical preparation, and chemical preparation.
The surface should be smooth, but not highly polished.
Preparation of this surface must be compatible with the gage,
bonding method, and base material.
7.2 Erroneous gage readings may be caused by poor bond-
FIG. 1 Designation of Strain Gage Bridge and Color Code of
ing of strain gages, which could be due to unremoved coatings
Lead Wires (Full Bridge)
suchaspaint,scale,rust,andoils.Poorbondingmayalsoresult
from applying gages to improperly prepared surfaces, such as
mirror smooth finishes or surfaces containing deep pits and
gouges.
7.3 Strain gage manufacturers supply surface preparation
suggestions and recommendations. This information should be
reviewed and considered when preparing base material sur-
faces for the particular gages selected.
8. Gage Installation—General
FIG. 2 Designations of Strain Gage Bridge and Color Code of 8.1 All work must be performed with clean hands and tools.
Lead Wires ( ⁄4 Bridge)
Allmaterialsneededshouldbeassembledandreadilyavailable
at the gage installation location.
5.4 A two- or three-element rosette gage should be used
8.2 Thespecificsurfacepreparationproceduresshouldbein
unless the strain state is unquestionably uniaxial. A single
accordancewiththeinstructionssuppliedforthebondingagent
element gage may be selected to measure the strain due to a
selected. Bonding agent handling and safety precautions
uniaxial strain state if the principal directions are known.
should be reviewed and carefully followed.
5.5 Temperature compensation of the gage should be se-
8.3 The detailed gage installation procedures available from
lected to match the thermal coefficient of expansion of the base
the strain gage manufacturer for the particular gage/bonding
material, where possible. As a note of caution, for extreme
technique system selected should be carefully reviewed and
temperature changes, nominal or handbook data on the thermal
rigorously followed. Deviations from these procedures, if any,
expansion characteristics of the base material may not be
should be documented and verified to ensure that the installa-
sufficiently accurate, and actual calibration may be required.
tion will yield suitably accurate results.
5.6 Strain gage manufacturers provide detailed critiques of
8.4 Gage handling and alignment procedures should be
the various factors which affect gage selection (1).
rigorously followed. Deviations, if any, should be documented.
5.7 For nonroutine applications, the advice of experienced
users and of strain gage manufacturers should be sought.
9. Gage Installation—Adhesive
Specific verification tests may be required to ensure accurate
9.1 Ensure that the proper adhesive is selected for a given
results.
gage type. Follow gage manufacturer’s recommendations for
selecting an adhesive.
6. Bonding Technique Selection
9.2 The environment to which a gage is to be subjected and
6.1 Selection of the proper bonding technique and agent is
test duration should be considered when selecting an adhesive.
important. Because the bonding agent becomes part of the
strain gage system, many of the gage selection factors should
9.3 Ensure that the adhesive to be used is not out-of-date
be considered in bonding technique or agent selection.
with regard to storage and shelf life requirements.
6.2 Additional selection factors include compatibility of the
9.4 Ensure that test material temperature range and gage/
bonding materials used in the selected gage construction with
bonding system temperature range are compatible.
thematerialundertest,environmentalconditions,andavailable
9.5 Temperatures and times should be monitored to ensure
installation time.
that the adhesive temperature and pot life requirements, if
6.3 Strain gages from different manufacturers may differ.
applicable, are not exceeded.
Generally, each manufacturer will supply instructions and
9.6 Adhesive curing methods and schedules should be
recommendations for bonding. These instructions should be
rigorously followed. Deviations, if any, should be documented.
considered when making a selection.
9.7 If curing with pressure is required, take special care to
make sure the pressure is proper and is distributed uniformly
The boldface numbers in parentheses refer to the list of references at the end of
this standard. over the entire gage. Nonuniform pressure may result in an
E1237−93(2009)
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