ASTM E1856-13(2021)

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: E1856 − 13 (Reapproved 2021)
Standard Guide for
Evaluating Computerized Data Acquisition Systems Used to
Acquire Data from Universal Testing Machines
This standard is issued under the fixed designation E1856; 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.
1. Scope* E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
1.1 This guide is intended to assist the user in the evaluation
E1012 Practice for Verification of Testing Frame and Speci-
and documentation of computerized data acquisition systems
men Alignment Under Tensile and Compressive Axial
used to acquire data from quasi-static tests, performed on
Force Application
universal testing machines. The report produced will aid in the
correct use and calibration of the computerized universal
3. Terminology
testing machine.
3.1 The definitions of mechanical testing terms that appear
1.2 The values stated in SI units are to be regarded as
in Terminology E6 apply to this guide.
standard. No other units of measurement are included in this
standard.
3.2 Definitions:
3.2.1 resolution, n—for a particular measurement device,
1.3 This standard does not purport to address all of the
the smallest change in the quantity being measured that causes
safety concerns, if any, associated with its use. It is the
a perceptible change in the corresponding indication.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 3.2.1.1 Discussion—Resolution may depend on the value
mine the applicability of regulatory limitations prior to use. (magnitude) of the quantity being measured.
1.4 This international standard was developed in accor-
3.2.1.2 Discussion—For paper charts or analog indicators,
dance with internationally recognized principles on standard-
theresolutionshouldnotbeassumedtobebetter(smaller)than
ization established in the Decision on Principles for the
⁄10 of the spacing between graduations. For digital devices, the
Development of International Standards, Guides and Recom-
best resolution potentially achievable is the smallest difference
mendations issued by the World Trade Organization Technical
between two different readings given by the display.
Barriers to Trade (TBT) Committee.
3.2.1.3 Discussion—For both analog and digital devices, the
actual resolution can be significantly poorer than described
2. Referenced Documents
above, due to factors such as noise, friction, etc.
2.1 ASTM Standards:
3.3 Definitions of Terms Specific to This Standard:
E4 Practices for Force Calibration and Verification of Test-
3.3.1 basic data, n—the digital equivalents of analog
ing Machines
counterparts, such as force and displacement measurements,
E6 Terminology Relating to Methods of Mechanical Testing
which under static conditions are traceable to national stan-
E8/E8M Test Methods for Tension Testing of Metallic Ma-
dards (see Fig. 1).
terials
E74 Practices for Calibration and Verification for Force- 3.3.2 computerized data acquisition system—a device that
Measuring Instruments collects basic data from a universal testing machine during a
E83 Practice for Verification and Classification of Exten- test and calculates and presents derived data based on the basic
someter Systems data collected.
3.3.3 derived data, n—additional numbers derived from the
This guide is under the jurisdiction of ASTM Committee E28 on Mechanical
basic data through computation using software algorithms,
Testing and is the direct responsibility of Subcommittee E28.15 on Automated
such as a peak force or a modulus value.
Testing.
Current edition approved Nov. 1, 2021. Published December 2021. Originally
3.3.4 data acquisition rate, n—the rate at which digital
approved in 1997. Last previous edition approved in 2013 as E1856–13. DOI:
samplesofeachwave-form(thatis,force,strain,displacement,
10.1520/E1856-13R21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or and so forth) are acquired, expressed in samples/second.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3.3.5 transducer-channel bandwidth—the frequency at
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. which the amplitude response of a transducer channel has
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1856 − 13 (2021)
those tested. Specimen types may be differentiated by material
(strength level), size, shape, or test performed.
6.2 Use one of the following procedures to evaluate and
document the conformity of the derived data.
6.2.1 Round Robin Procedure:
6.2.1.1 Perform a round robin involving at least two other
universal testing machines. The other testing machines need
not necessarily be computerized.
NOTE 1—It is preferable to use universal testing machines of varying
types so that systemic problems are not masked.
6.2.1.2 If possible, configure the universal testing machines
in such a way as to be able to obtain a graphic record of the
tests. The graphic record may be generated by analog signal
sources, the computerized data acquisition system, or may be
generated manually from digital data recorded by the comput-
erized data acquisition system.
6.2.1.3 Ascertain that all readout and recording devices
FIG. 1 Basic Data and Derived Data
have been calibrated in accordance with Practices E4, E83,or
other applicable standards.
fallen by 3 dB; that is, the measured signal is in error by about
6.2.1.4 Test at least five specimens of each specimen type
30 % and the phase shift is 45° or greater.
on each machine in conformance with the applicable test
3.3.5.1 Discussion—The precise amplitude and phase re-
methods or established procedures.
sponses vary with the electrical design of the computerized
NOTE 2—It may be desirable to test many more specimens after an
data acquisition system, but the 3 dB bandwidth (expressed in
initial screening, particularly if high standard deviations are observed on
hertz)isasimplesinglemeasureofresponsiveness(seeFig.2).
all machines.
6.2.1.5 Obtain the derived data from the computerized data
4. Summary of Guide
acquisition system or graphic records of the tests from each
4.1 Comparative tests are performed to determine if the
machine, or both.
derived data acquired with a computerized universal testing
6.2.1.6 From the graphic records obtained, manually calcu-
machine agree with results acquired on the same machine from
late the same test results obtained by the computerized data
graphical records or with results acquired on other testing
acquisition system.
machines to ensure that the materials being tested are correctly
6.2.1.7 Calculate the average and standard deviation of both
characterized.
the manually calculated results and the derived data obtained
by the computerized data acquisition system(s) within each
5. Significance and Use
group of five or more specimens.
5.1 This guide is recommended to be used by anyone
6.2.1.8 Investigate, identify, and correct, if necessary, the
acquiring data from a universal testing machine using a
cause of any average results obtained by the computer that
computerized data acquisition system.
differ from the manually obtained average results, or the
average results obtained by other testing machines, by more
6. Procedure
than 2.0 % of the average or more than one standard deviation,
6.1 Chooseatleastfivedifferenttestspecimentypesthatare
whichever is greater. In all cases, use the smallest non-zero
representative of the specimens commonly tested on the
standard deviation for evaluations.
universal testing machine. If the universal testing machine is
6.2.1.9 Investigate, identify, and correct, if necessary, the
used to test fewer than five different specimen types, choose all
cause of any standard deviations of the derived data obtained
by the computerized data acquisition system that are more than
two times the standard deviation obtained manually or by the
other machines.
NOTE 3—Differences in averages and standard deviations of these
magnitudes are quite often due to variations in the material being tested,
and a complete statistical evaluation of the data using methods such as
Practice E691 may be necessary.
6.2.2 Single Machine Procedure:
6.2.2.1 This procedure may be used for universal testing
machines with the capability of producing graphic records
from which derived data can be manually calculated.
6.2.2.2 Configure the testing machine in such a way as to be
FIG. 2 Bandwidth able to obtain a graphic record of the tests. The graphic record
E1856 − 13 (2021)
may be generated by analog signal sources, the computerized data from the computerized data acquisition system disagree,
data acquisition system, or may be generated manually from the difference may be due to incorrect inputs to the computer
digital data recorded by the computerized data acquisition algorithms.
system.
7.1.4 Algorithms Used—If the results calculated by manual
6.2.2.3 Ascertainthatallreadoutandrecordingdevicesused
methodsfromthegraphicrecordagreewiththeothermachines
(analog or digital, or both) have been calibrated in accordance
but the derived data from the computer disagree, the difference
with Practices E4, E83, or other applicable standards.
may be due to algorithms used by the computerized data
6.2.2.4 Ascertain that all transducers with their readout or
acquisition system.
recording devices, or both, including the devices producing the
7.1.5 Algorithms That Are Not Working Properly—If the
graphic record, have the required transducer-channel band-
results calculated by manual methods from the graphic record
width for the tests performed with the machine (see Appendix
agree with the other machines but the derived data from the
X2).
computerized data acquisition system disagree, the difference
6.2.2.5 Test at least five specimens of each specimen type in
may be due to algorithms that are not working properly.
conformance with the applicable test methods or established
7.1.6 Ambiguity in the Interpretation of the Test Method—
procedures, obtaining both a graphic record and derived data
The writer(s) of the algorithms used, or the user, or both, may
from the computerized data acquisition system at the same
be interpreting the test method differently or incorrectly.
time.
7.1.7 Differences in Gripping and Other Apparatus in Con-
6.2.2.6 From the graphic record, determine the same test
tact with the Specimen—Differences in gripping and other
results as are calculated by the computerized data acquisition
apparatus in contact with the specimen may cause premature
system.
failure of the specimen or act as a heat sink and cause
6.2.2.7 Calculate the average and standard deviation of both
differences in elongation related results.
the manually calculated results and the derived data obtained
7.1.8 Alignment of the Test Piece—Poor alignment can
by the computerized data acquisition system (derived data)
cause lower-than-normal test results or poorly formed stress-
within each group of five specimens.
strain curves, or both, in the elastic region of the curve (see
6.2.2.8 Investigate, identify, and correct, if necessary, the
Practice E1012).
cause of any average derived data obtained by the computer-
7.1.9 Insufficient bandwidth in one or more of the trans-
ized data acquisition system that differ from the manually
ducer channels (see Appendix X2).
obtained average results by more than 2.0 % of the average or
more than one standard deviation, whichever is greater. In all
NOTE 4—Differences are just as likely to be due to problems with the
manually calculated results as they are to problems with the computer
cases, use the smallest non-zero standard deviation for evalu-
generated derived data.
ations.
NOTE 5—For additional information, see the appendix on Factors
6.2.2.9 Investigate, identify, and correct, if necessary, the
Affecting Tension Test Results in Test Methods E8/E8M.
cause of any standard deviations of the derived data obtained
7.2 Adifferenceinthestandarddeviationbetweenmachines
by the computerized data acquisition system that are more than
may be due to one or more of the following:
two times the standard deviation of results obtained manually.
7.2.1 Differences in Resolution—Poor resolution can show
7. Test Result Evaluation up in two forms. A standard deviation of zero may indicate
poor resolution. Alternatively, if two or more discrete derived
7.1 A bias in average results between machines or readouts
data occur with a difference between them that is large relative
may be due to one or more of the following:
to the result being measured, poor resolution may be the cause.
7.1.1 Calibration Differences—A bias in all of the force
Example: 206, 206, 210, 206, 210 (see Appendix X3).
results observed usually indicates a difference in calibration. If
7.2.2 Specimen Dimension Precision—If derived-data force
maximum forces disagree between the manual and computer-
standard deviations agree and derived-data stress standard
ized results, it may be due to differences in calibration between
deviations differ, the difference is probably due to imprecise
parts of the machine (see Appendix X1). If force results are in
measurements of cross sectional
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