ASTM D1780-05(2020)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D1780 − 05 (Reapproved 2020)
Standard Practice for
Conducting Creep Tests of Metal-to-Metal Adhesives
This standard is issued under the fixed designation D1780; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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 U.S. Department of Defense.
1. Scope sion Loading (Metal-to-Metal)
1.1 This practice covers the determination of the amount of
3. Terminology
creep of metal-to-metal adhesive bonds due to the combined
effects of temperature, tensile shear stress, and time.
3.1 Definitions—Many of the terms in this practice are
defined in Terminology D907.
NOTE 1—Since the characteristics that render a material resistant to
3.2 Definitions of Terms Specific to This Standard:
creepundertheconditionoftestarenotyetcompletelyknown,thedetails
3.2.1 creep, n—the time-dependent part of the strain that
of the procedure considered herein are those known to have important
influences. Since other equally important characteristics may be discov-
resultsfromexposuretoaconstanttemperatureandload(Note
ered in the future, the recommended details are largely advisory in nature.
2).Thatis,thecreepatagivenelapsedtimeisequaltothetotal
1.2 Test periods depend upon the reasonable life expected strain at the given time minus the instantaneous strain (Note 3)
from the material in service.The uncertainties of extrapolation on loading. The creep extension is expressed as a percentage,
should be considered in deciding upon the length of the test. that is, the extension divided by the initial unstretched length
multiplied by 100.
1.3 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information
NOTE 2—Constant-stress creep tests are desirable. The usual one is a
constant deadweight load test. Creep tests made by means of spring
only.
loading or fixtures which involve deflection or strain measurements in the
1.4 This standard does not purport to address all of the
fixture for the application of load are unsatisfactory. However, if the total
safety concerns, if any, associated with its use. It is the
deformation or extension in the adhesive is large, corrections must be
responsibility of the user of this standard to establish appro- made to compensate for the decrease in stress because of the extension in
the adhesive.
priate safety, health, and environmental practices and deter-
NOTE 3—Since the time-dependent strain develops rapidly even during
mine the applicability of regulatory limitations prior to use.
the application of the load, the instantaneous strain for recovery is usually
1.5 This international standard was developed in accor-
difficult to determine, except in the arbitrary manner given in the
dance with internationally recognized principles on standard-
definitions of instantaneous strain and instantaneous recovery.
ization established in the Decision on Principles for the
3.2.2 deformation, n—the total strain at any specific time.
Development of International Standards, Guides and Recom-
3.2.3 failure, n—rupture of the specimen, or exceeding the
mendations issued by the World Trade Organization Technical
strain requirements of a specific design.
Barriers to Trade (TBT) Committee.
3.2.4 instantaneous recovery, n—the decrease in strain oc-
curring immediately upon unloading a specimen.As in instan-
2. Referenced Documents
2 taneous strain, a more reproducible value is obtained if the
2.1 ASTM Standards:
decrease in strain is measured after a given small increment of
D907Terminology of Adhesives
time (such as 1 min) following unloading. The increment of
D1002Test Method for Apparent Shear Strength of Single-
time used shall be specified. The instantaneous recovery shall
Lap-Joint Adhesively Bonded Metal Specimens by Ten-
be expressed in the same units as strain, that is, the decrease in
length divided by the gage length usually, in inches per inch.
This practice is under the jurisdiction ofASTM Committee D14 on Adhesives
3.2.5 instantaneous strain, n—the strain occurring immedi-
and is the direct responsibility of Subcommittee D14.80 on Metal Bonding
ately upon loading a creep specimen. Since it is nearly
Adhesives.
impossible to obtain strain readings at the instant of loading,
Current edition approved Dec. 15, 2020. Published December 2020. Originally
the strain after a given small increment of time (such as 1 min)
approved in 1960. Last previous edition approved in 2012 as D1780–05 (2012).
DOI: 10.1520/D1780-05R20.
after loading is a more reproducible value. The increment of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
time used shall be specified. The instantaneous strain shall be
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
expressedintheunitsasstrain,thatis,theextensiondividedby
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the gage length, usually in inches per inch.
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D1780 − 05 (2020)
3.2.6 recovery, n—the time-dependent portion of the de- period to 61°C. State any fluctuation beyond this tolerance in
crease in strain following unloading of a specimen at the same reporting the test. Make the range of the normal control cycle
constanttemperatureastheinitialtest.Recoveryisequaltothe a matter of record for the apparatus.
total decrease in strain minus the instantaneous recovery (see
7.3 Take care to obtain reliable and accurate master tem-
Note 3). The recovery shall be expressed in the same units as
perature standards and check these at suitable intervals. When
instantaneous recovery.
thermocouples are used in the test, use one of known
calibration, checked before testing and after long-time expo-
4. Significance and Use
sures.
4.1 This practice provides information on the creep of
7.4 Use two thermocouples for measuring temperatures of
bonded metal parts subjected to combined effects of
the specimens throughout the test. Place these on opposite
temperature, shear, and time.
edges of the specimen at the end of the lap joint in the bond
line. In furnaces not having equalized temperature over a
5. Possibilities and Limitations
51-mm(2-in.)zoneplaceadditionalthermocouplesateachend
5.1 The primary use of creep tests is to provide basic data
of the 51-mm center section of the specimen to ensure equal
for the choice of safe working stresses for applications in
temperature distribution.
which allowable deformation within the service life of the
7.5 Keep a continual record of the thermocouple measure-
structure is the criterion of failure.
ments throughout the test. An automatic recorder of the
5.2 Creep is an extremely sensitive index of strength, and
strip-chart type is preferred. If automatic equipment is not
usually does not vary as a linear function of stress. (It depends
available, make visual observations at sufficiently close inter-
on the material, stress, temperature, and time.)
valsoftimetoensureaccuracyoftemperaturecontrolthrough-
5.3 Intheapplicationofthefollowingtestrequirementsand
out the test.
recommendations it is assumed that the test specimens of a
given adhesive bond are essentially comparable and truly
8. Vibration Control
representative of the material. In tests conducted to show the
8.1 Since creep tests especially are quite sensitive to shock
effects of temperature or stress as variables, great care must be
and vibration, select the location of the testing apparatus for a
used to ensure that the specimens are representative of the
minimum of disturbance. When the possible locations are not
adhesive bond. Departure from this assumption may introduce
free of vibrations, design the test equipment and mounting so
discrepancies as great as, if not greater than, those due to
that the specimen is isolated from shock and vibration.
departure from details of procedure outlined in this practice.
9. Test Specimens
6. Apparatus
9.1 Prepar
...