American Association State
Highway and Transportation Officials Standards
AASHTO No: T67
Designation: E 4 – 07
Standard Practices for
Force Verification of Testing Machines1
This standard is issued under the fixed designation E 4; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
2. Referenced Documents
2.1 ASTM Standards: 2
D 76 Specification for Tensile Testing Machines for Textiles
E 74 Practice of Calibration of Force-Measuring Instruments for Verifying the Force Indication of Testing Machines
E 467 Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fatigue Testing System
1. Scope
1.1 These practices cover procedures for the force verification, by means of standard calibration devices, of tension or
compression, or both, static or quasi-static testing machines
(which may, or may not, have force-indicating systems). These
practices are not intended to be complete purchase specifications for testing machines. Testing machines may be verified by
one of the three following methods or combination thereof:
1.1.1 Use of standard weights,
1.1.2 Use of equal-arm balances and standard weights, or
1.1.3 Use of elastic calibration devices.
3. Terminology
3.1 Definitions:
3.1.1 testing machine (force-measuring type)—a mechanical device for applying a force to a specimen.
3.1.1.1 portable testing machine (force-measuring type)—a
device specifically designed to be moved from place to place
and for applying a force (load) to a specimen.
3.1.2 tension testing machine, CRT (constant-rateoftraverse)—a mechanical device for applying a load (force) to
a specimen and in which the force is measured by means of a
pendulum.
3.1.3 force—in the case of testing machines, a force measured in units such as pound-force, newton, or kilogram-force.
3.1.3.1 Discussion—The pound-force is that force which
acting on a 1-lb mass will give to it an acceleration of 9.80665
m/s2(32.1740 ft/s2). The newton is that force which acting on
a 1-kg mass will give to it an acceleration of 1 m/s2.
3.1.4 accuracy—the specified permissible variation from
the correct value. A testing machine is said to be accurate if the
indicated force is within the specified permissible variation
from the actual force.
3.1.4.1 Discussion—In these methods the word “accurate”
applied to a testing machine is used without numerical values,
for example, “An accurate testing machine was used for the
investigation.” The accuracy of a testing machine should not be
confused with sensitivity. For example, a testing machine
might be very sensitive; that is, it might indicate quickly and
NOTE 1—These practices do not cover the verification of all types of
testing machines designed to measure forces, for example, the constantrate-of-loading type which operates on the inclined-plane principle. This
type of machine may be verified as directed in the applicable appendix of
Specification D 76.
1.2 The procedures of 1.1.1-1.1.3 apply to the verification of
the force-indicating systems associated with the testing machine, such as a scale, dial, marked or unmarked recorder chart,
digital display, etc. In all cases the buyer/owner/user must
designate the force-indicating system(s) to be verified and
included in the report.
1.3 Since conversion factors are not required in this practice, either inch-pound units, SI units, or metric values can be
used as the standard.
1.4 Forces indicated on displays/printouts of testing machine data systems—be they instantaneous, delayed, stored, or
retransmitted—which are verified with provisions of 1.1.1,
1.1.2, or 1.1.3, and are within the 61 % accuracy requirement,
comply with Practices E 4.
1.5 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.
1
These practices are under the jurisdiction of ASTM Committee E28 on
Mechanical Testing and is the direct responsibility of Subcommittee E28.01 on
Calibration of Mechanical Testing Machines and Apparatus.
Current edition approved Jan. 1, 2007. Published January 2007. Originally
approved in 1923. Last previous edition approved in 2003 as E 4 – 03.
2
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
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E 4 – 07
3.1.12 resolution of the force indicator—smallest change of
force that can be estimated or ascertained on the force
indicating apparatus of the testing machine, at any applied
force. Appendix X1. describes a method for determining
resolution.
3.1.12.1 resolution of analog type force indicators (scales,
dials, recorders, etc.)—the resolution is the smallest change in
force indicated by a displacement of a pointer, or pen line. The
resolution is calculated by multiplying the force corresponding
to one graduation by the ratio of the width of the pointer or pen
line to the center to center distance between two adjacent
graduation marks. The typical ratios used are 1:1, 1:2, 1:5, or
1:10. A spacing of 0.10 in. (2.5 mm) or greater is recommended
for the ratio of 1:10. A ratio less than 1:10 should not be used.
(1) Discussion—If a force indicating dial has graduations
spaced every 0.080 in. (2.0 mm), the width of the pointer is
approximately 0.040 in. (1.0 mm), and one graduation represent 5 lbf (25N). The ratio used would be 1:2 and the resolution
would be equal to 2-1/2 lbf (12-1/2 N).
3.1.12.2 resolution of digital type force indicators (numeric,
displays, printouts, etc.)—the resolution is the smallest change
in force that can be displayed on the force indicator, at any
applied force.
(1) Discussion—A single digit or a combination of digits
may be the smallest change in force that can be indicated.
3.1.13 If the force indication, for either type of force
indicator, fluctuates by more than twice the resolution, as
described in 3.1.12.1 or 3.1.12.2, the resolution, expressed as a
force, shall be equal to one-half the range of the fluctuation.
definitely small changes in force, but nevertheless, be very
inaccurate. On the other hand, the accuracy of the results is in
general limited by the sensitivity.
3.1.5 error (or the deviation from the correct value)—in the
case of a testing machine, the difference obtained by subtracting the force indicated by the calibration device from the force
indicated by the testing machine.
3.1.5.1 Discussion—The word “error” shall be used with
numerical values, for example, “At a force of 30 000 lbf (133
kN), the error of the testing machine was + 15 lbf (67 N).”
3.1.6 percent error—in the case of a testing machine, the
ratio, expressed as a percent, of the error to the correct value of
the applied force.
3.1.6.1 Discussion—The test force, as indicated by the
testing machine, and the applied force, as computed from the
readings of the verification device, shall be recorded at each
test point. The error, E, and the percent error, Ep, shall be
calculated from these data as follows:
E5A2B
(1)
Ep 5 [~A 2 B!/B] 3 100
where:
A = force indicated by machine being verified, lbf (or N),
and
B = correct value of the applied force, lbf (or N), as
determined by the calibration device.
3.1.7 correction—in the case of a testing machine, the
difference obtained by subtracting the indicated force from the
correct value of the applied force.
3.1.8 permissible variation (or tolerance)—in the case of
testing machines, the maximum allowable error in the value of
the quantity indicated.
3.1.8.1 Discussion—It is convenient to express permissible
variation in terms of percentage of error. The numerical value
of the permissible variation for a testing machine is so stated
hereafter in these practices.
3.1.9 capacity range—in the case of testing machines, the
range of forces for which it is designed. Some testing machines
have more than one capacity range, that is, multiple ranges.
3.1.10 verified range of forces—in the case of testing
machines, the range of indicated forces for which the testing
machine gives results within the permissible variations specified.
3.1.10.1 calibration, n—in the case of force testing machines, the process of comparing the force indication of the
machine under test to that of a standard, making adjustments as
needed to meet error requirements.
3.1.10.2 verification, n—in the case of force testing machines, the process of comparing the force indication of the
machine under test to that of a standard and reporting results,
without making adjustments.
3.1.11 elastic calibration device—a device for use in verifying the force readings of a testing machine consisting of an
elastic member(s) to which forces may be applied, combined
with a mechanism or device for indicating the magnitude (or a
quantity proportional to the magnitude) of deformation under
force.
4. Significance and Use
4.1 Testing machines that apply and indicate force are used
in many industries, in many ways. They may be used in a
research laboratory to measure material properties, and in a
production line to qualify a product for shipment. No matter
what the end use of the machine may be, it is necessary for
users to know the amount of force that is applied and indicated,
and that the accuracy of the force is traceable to the National
Institute of Standards and Technology (NIST), formerly NBS.
Practices E 4 provides a procedure to verify these machines, in
order that the indicated forces may be traceable. A key element
to this NIST traceability is that the devices used in the
verification have known force characteristics, and have been
calibrated in accordance with Practice E 74.
4.2 The procedures in Practices E 4 may be used by those
using, manufacturing, and providing calibration service for
testing machines and related instrumentation.
5. Calibration Devices
5.1 When verifying testing machines, use calibration devices only over their Class A force ranges as determined by
Practice E 74.
6. Advantages and Limitations of Methods
6.1 Verification by Standard Weights—Verification by the
direct application of standard weights to the weighing mechanism of the testing machine, where practicable, is the most
accurate method. Its limitations are: (1) the small range of
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E 4 – 07
7.3.1 Introduction of the new force measuring devices shall
require that interchangeability be established per 7.3.
7.4 A Practices E 4 Verification consists of at least two
verification runs of the forces contained in the force range(s)
selected. See 10.1 and 10.3.
7.4.1 If the initial verification run produces values within
the Practices E 4 requirements of Section 18, the data may be
used “as found” for run one of the two required for the new
verification report.
7.4.2 If the initial verification run produces any values
which are outside of the Practices E 4 requirements, the “as
found” data may be reported and may be used in accordance
with applicable quality control programs. Calibration adjustments shall be made to the force indicator system(s), after
which the two required verification runs shall be conducted and
reported in the new verification report and certificate.
7.4.3 Calibration adjustments may be made to improve the
accuracy of the system. They shall be followed by the two
required verification runs, and issuance of a new verification
report and certificate.
forces that can be verified, (2) the nonportability of any large
amount of standards weights, and (3) its nonapplicability to
horizontal testing machines or vertical testing machines having
weighing mechanisms that are not designed to be actuated by
a downward force.
6.2 Verification by Equal-Arm Balance and Standard
Weights—The second method of verification of testing machines involves measurement of the force by means of an
equal-arm balance and standard weights. This method is
limited to a still smaller range of forces than the foregoing
method, and is generally applicable only to certain types of
hardness testing machines in which the force is applied through
an internal lever system.
6.3 Verification by Elastic Calibration Devices—The third
method of verification of testing machines involves measurement of the elastic strain or deflection under force of a ring,
loop, tension or compression bar, or other elastic device. The
elastic calibration device is free from the limitations referred to
in 6.1 and 6.2.
7. System Verification
7.1 A testing machine shall be verified as a system with the
force sensing and indicating devices (see 1.2 and 1.4) in place
and operating as in actual use.
7.1.1 If this is not technically possible, refer to Annex A1,
Verifying the Force Measuring System out of the Test Machine.
Out of the test machine verifications shall be in accordance
with the main body of Practices E 4 and its Annex A1
7.2 System verification is invalid if the devices are removed
and checked independently of the testing machine unless
verification is performed according to Annex A1.
7.3 Many testing machines utilize more than one force
measuring device in order to obtain more accurate force
indication at lower applied forces. These devices are routinely
installed and uninstalled in the testing machine. For such
devices, interchangeability shall be established during the
initial verification and shall be reestablished after an adjustment is performed. This is accomplished by performing a
normal verification with the device in place as during normal
use. It is advisable that orientation be kept consistent, such as
by noting the direction of the cable connector so that when
reinstalling the device, the orientation will be repeated. Remove and reinstall the device between the two verification runs
to demonstrate interchangeability. Repeat the procedure for
each interchangeable force measuring device used in the
testing machine.
8. Gravity and Air Buoyancy Corrections
8.1 In the verification of testing machines, where standard
weights are used for applying forces directly or through lever
or balance-arm systems, correct the force for the local value of
gravity and for air buoyancy.
8.2 Calculate the force exerted by a weight in air as follows:
S
Mg
d
Force 5 9.80665 1 2 D
D
(2)
where:
M = mass of the weight,
g = local acceleration due to gravity, m/s2,
d = air density (0.0012 Mg/m3), and
D = density of the weight in the same units as d.
For use in verifying testing machines, corrections for local
values of gravity and air buoyancy can be made with sufficient
accuracy using the multiplying factors from Table 1.
NOTE 2—If M, the mass of the weight is in pounds, the force will be in
pounds-force units. If M is in kilograms, the force will be in kilogramforce units. These customary force units are related to the newton, the SI
unit of force, by the following relationships:
1 lbf 5 4.448222 N1 kgf 5 9.80665 N ~exact!
(3)
9. Application of Force
9.1 In the verification of a testing machine, approach the
force by increasing the force from a lower force.
TABLE 1 Unit Force Exerted by a Unit Mass in Air at Various Latitudes
Elevation Above Sea Level, ft(m)
Latitude,°
−100 to 500
(−30.5 to 152)
500 to 1500
(152 to 457)
1500 to 2500
(457 to 762)
2500 to 3500
(762 to 1067)
3500 to 4500
(1067 to 1372)
4500 to 5500
(1372 to 1676)
20
25
30
35
40
45
50
55
0.9978
0.9981
0.9985
0.9989
0.9993
0.9998
1.0003
1.0007
0.9977
0.9980
0.9984
0.9988
0.9993
0.9997
1.0002
1.0006
0.9976
0.9979
0.9983
0.9987
0.9992
0.9996
1.0001
1.0005
0.9975
0.9979
0.9982
0.9987
0.9991
0.9996
1.0000
1.0005
0.9975
0.9978
0.9982
0.9986
0.9990
0.9995
0.9999
1.0004
0.9974
0.9977
0.9981
0.9985
0.9989
0.9994
0.9999
1.0003
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E 4 – 07
NOTE 3—For any testing machine the errors observed at corresponding
forces taken first by increasing the force to any given test force and then
by decreasing the force to that test force, may not agree. Testing machines
are usually used under increasing forces, but if a testing machine is to be
used under decreasing forces, it should be calibrated under decreasing
forces as well as under increasing forces.
NOTE 6—Example: A testing machine has a full-scale range of 5000 lbf
and the resolution of the force indicator is 0.0472 lbf. The lowest possible
verified force is 9.44 lbf (0.0472 3 200). Instead of decades starting at
9.44, 94.4 and 944 lbf, three decades, starting at 10, 100, and 1000 lbf are
selected to cover the verified range of forces. Suitable verification forces
are 10, 20, 40, 70, 100, 200, 400, 700, 1000, 2000, 3000, 4000, 5,000 lbf.
Note that the uppermost decade is not a complete decade and is terminated
with the upper limit of the verified force range. The 3000 lbf reading was
added because the difference between 2000 and 4000 was greater than
one-third of 5000. If the alternative distribution of forces is used, the
verification forces selected would be 10, 25, 50, 75, 100, 250, 500, 750,
1000, 2500, 3750, 5000.
9.2 Testing machines that contain a single test area and
possess a bidirectional loading and weighing system must be
verified separately in both modes of weighing.
9.3 High-speed machines used for static testing must be
verified in accordance with Practices E 4.
10.4 All selected verification forces shall be applied twice
during the verification procedure. Applied forces on the second
run are to be approximately the same as those on the first run.
10.5 Approximately 30 s after removing the maximum force
in a range, record the return to zero indicator reading. This
reading shall be 0.0 6 either the resolution, 0.1 % of the
maximum force just applied, or 1 % of the lowest verified force
in the range, whichever is greater.
NOTE 4—Caution: Practices E 4 verification values are not to be
assumed valid for high-speed or dynamic testing applications (see Practice
E 467).
NOTE 5—The error of a testing machine of the hydraulic-ram type, in
which the ram hydraulic pressure is measured, may vary significantly with
ram position. To the extent possible such machines should be verified at
the ram positions used.
10. Selection of Verification Forces
10.1 Determine the upper and lower limits of the verified
force range of the testing machine to be verified. In no case
shall the verified force range include forces below 200 times
the resolution of the force indicator.
10.2 If the lower limit of the verified force range is greater
than or equal to one-tenth of the upper limit, five or more
different verification forces shall be selected such that the
difference between two adjacent verification forces is greater
than or equal to one twentieth and less than or equal to
one-third the difference between the upper and lower limits of
the verified force range. One verified force shall be the lower
limit of the verified force range and another verified force shall
be the upper limit. (Fewer verification forces are required for
testing machines designed to measure only a small number of
discrete forces, such as certain hardness testers, creep testers,
etc.)
10.3 If the lower limit of the verified force range is less than
one-tenth the upper limit, verification forces shall be selected
as follows:
10.3.1 Starting with the lower limit of the verified force
range, establish overlapping force decades such that the maximum force in each decade is ten times the lowest force in the
decade. The lowest force in the next higher decade is the same
as the highest force in the previous decade. The highest decade
might not be a complete decade.
10.3.2 Five or more different verification forces shall be
selected per decade such that the difference between two
adjacent verification forces is greater than or equal to onetwentieth and less than or equal to one-third the difference
between the maximum and the minimum force in that decade.
It is recommended that starting with the lowest force in each
decade, the ratio of the verification forces to the lowest force in
the decade are 1:1, 2:1, 4:1, 7:1, 10:1 or 1:1, 2.5:1, 5:1, 7.5:1,
10:1.
10.3.3 If the highest decade is not a complete decade,
choose verification forces at the possible ratios and include the
upper limit of the verified force range, If the difference
between two adjacent verification forces is greater than onethird of the upper limit, add an additional verification force.
11. Eccentricity of Force
11.1 For the purpose of determining the verified force range
of a testing machine, apply all calibration forces so that the
resultant force is as nearly along the axis of a testing machine
as is possible.
NOTE 7—The effect of eccentric force on the accuracy of a testing
machine may be determined by verification readings taken with calibration devices placed so that the resultant force is applied at definite
distances from the axis of the machine, and the verified force range
determined for a series of eccentricities.
A. VERIFICATION BY STANDARD
WEIGHTS
12. Procedure
12.1 Place standard metal weights of suitable design, finish,
and adjustment on the weighing platform of the testing
machine or on trays or other supports suspended from the force
measuring mechanism in place of the specimen. Use weights
certified within five years to be correct within a limit of error
of 0.1 %. Apply the weights in increments and remove in the
reverse order. Arrange the weights symmetrically with respect
to the weighing platform, so that the center of gravity of the
force lies in the vertical line through the center of the platform.
Record the applied force and the indicated force for each test
load applied, and the error and the percent error calculated
from these data.
NOTE 8—The method of verification by direct application of standard
weights can be used only on vertical testing machines in which the force
on the weighing table, hydraulic support, or other weighing device is
downward. The total force is limited by the size of the platform and the
number of weights available. Fifty-pound (22.7-kg) weights are usually
convenient to use. This method of verification is confined to small testing
machines and is rarely used above 1000 or 2000 lb.
NOTE 9—In connection with the required limit of error of 0.1 % it may
be noted that, in addition to the National Institute for Standards and
Technology, many of the states, some counties, and some universities have
departments or offices of weights and measures equipped and staffed to
certify weights to tolerances closer than the requirement of a limit of error
of 0.1 %.
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E 4 – 07
only within its Class A force range and identified with the
verification readings for which it is used.
15.2 To ensure a stable zero, flex the elastic device from no
force to the maximum force at which the device will be used.
Repeat as necessary, allowing sufficient time for stability.
15.3 There are two methods for using elastic calibration
devices:
15.3.1 Follow-the-Force Method—The force on the elastic
calibration device is followed until the force reaches a nominal
graduation on the force-readout scale of the testing machine.
Record the force on the elastic calibration device.
15.3.2 Set-the-Force Method—The nominal force is preset
on the elastic calibration device, and the testing machine force
readout is read when the nominal force on the elastic calibration device is achieved.
15.4 After selecting suitable test force increments, obtain
zero readings for both machine and elastic device, and apply
forces slowly and smoothly during all verification measurements.
15.5 The calibration procedure must ensure that use of the
maximum force indicator, recorder, or other accessory force
devices does not cause testing machine errors to exceed the
acceptable tolerances of 18.1.
15.6 Record the indicated force of the testing machine and
the applied force from the elastic calibration device (temperature corrected as necessary), as well as the error and percentage
of error calculated from the readings.
15.7 Under certain conditions, multi-device setups may be
used in compression loading. All devices to be loaded in
parallel should be the same height (shims may be used) and the
machine’s load axis should be coincidental with the force axis
of the device setup. This is necessary so that a net moment is
not applied to the testing machine loading member. Multidevice setups are not recommended unless the use of a single
calibration device is not practical.
B. VERIFICATION OF HARDNESS TESTING
MACHINES BY EQUAL-ARM BALANCE AND
STANDARD WEIGHTS
13. Procedure
13.1 Position the balance so that the indenter of the testing
machine being calibrated bears against a block centered on one
pan of the equal-arm balance, the balance being in its equilibrium position when the indenter is in that portion of its travel
normally occupied when making an impression. Place standard
weights complying with the requirements of Section 12 on the
opposite pan to balance the load exerted by the indenter.
NOTE 10—This method may be used for the verification of testing
machines other than hardness-testing machines by positioning the forceapplying member of the testing machine in the same way that the indenter
of a hardness-testing machine is positioned. For other methods of
verifying hardness testing machines see the applicable ASTM test method.
13.2 Since the permissible travel of the indenter of a
hardness-testing machine is usually very small, do not allow
the balance to oscillate or swing. Instead, maintain the balance
in its equilibrium position through the use of an indicator such
as an electric contact, which shall be arranged to indicate when
the reaction of the indenter force is sufficient to lift the pan
containing the standard weights.
13.3 Using combinations of fractional weights, determine
both the maximum value of the dead-weight force that can be
lifted by the testing machine indenter force during each of ten
successive trials, and the minimum value that cannot be lifted
during any one of ten successive trials. Take the correct value
of the indenting force as the average of these two values. The
difference between the two values shall not exceed 0.5 % of the
average value.
C. VERIFICATION BY ELASTICCALIBRATION DEVICE
14. Temperature Equalization
14.1 When using an elastic calibration device to verify the
readings of a testing machine, place the device near to, or
preferably in, the testing machine a sufficient length of time
before the test to assure that the response of device is stable.
14.2 During the verification, measure the temperature of the
elastic device within 62°F or 61°C by placing a calibrated
thermometer as close to the device as possible.
14.3 Elastic calibration devices not having an inherent
temperature-compensating feature must be corrected mathematically for the difference between ambient temperature and
the temperature to which its calibration is referenced.
Temperature-correction coefficients should be furnished (if
applicable) by the manufacturer of the calibration device. Refer
to Practice E 74 for further information.
16. Constant-Rate-of-Traverse CRT-Type Testing
Machines
16.1 In the verification of pendulum-type testing machines
having capacities of 2000 lbf or 10 kN or less, special
procedures must be followed in order to properly account for
the effects of friction, inertia, etc. These machines are usually
of the vertical type and usually can be verified by standard
weights. For pendulum-type tension-testing machines in which
the forces act in a horizontal direction or when verification by
standard weights is not practical, other methods of verification
may be used. In such cases, devices similar to the equal-arm
balances, or the elastic calibrating devices may be used,
provided precautions as set forth herein are taken.
16.2 Either or both of two alternative procedures (see 16.5
and 16.6) may be used, depending on the requirements of
specifications of materials to be tested, recommendations of the
testing machine manufacturer, or other pertinent consideration.
16.3 For any range of forces, verify the tension-testing
machine with at least five test forces. Each successive test load
shall differ from the previous test force by not more than one
third of the difference between the maximum and minimum
test forces.
15. Procedure
15.1 Place the elastic device in the testing machine so that
its center line coincides with the center line of the heads of the
testing machine. Record the Practice E 74 Class A verification
value which establishes the lowest limit, or force level,
allowable for the calibration device’s loading range (see
Practice E 74). Each elastic calibration device is to be used
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E 4 – 07
CALCULATION AND REPORT
16.3.1 For CRT machines, the verified range of force shall
in no case include forces below 15 % of the capacity range.
16.4 Except as set forth in Section 16, other requirements of
Practices E 4 shall be applicable.
16.5 Procedure 1 (Pawls Inoperative):
16.5.1 Verify the machine in the condition under which it is
to be used, with all attachments and recording mechanisms in
operation as they are to be used in actual testing, except that
any pawls or other detents in the weighing mechanism shall
have been rendered inoperative. In verification, apply the test
force and minimize the effect of friction by gently oscillating
the pendulum to ensure that the force of the applied test force
is in equilibrium with the force exerted by the pendulum.
16.5.2 Examine the machine to detect any friction or slack
in the weighing, indicating, or recording mechanisms and
estimate the actual effect in terms of units in which the machine
is calibrated.
16.5.3 Follow 16.6 to determine the effects described in
16.5.2.
16.6 Procedure 2 (Pawls Operating):
16.6.1 Verify the machine in the condition under which it is
to be used with all attachments and recording mechanisms in
operation as they are to be used in actual testing. In verification, apply the test force with the pawls or other detents in the
normal operating position. After the pendulum has come to
rest, disengage the pawls or detents, if any, and depress the
pendulum slightly as if the force were decreased (approximately 5 % of the capacity range). Next, with the pawls or
detents engaged, release the pendulum smoothly and at a rate
approximately the rate of movement of the pendulum during an
actual test. The point at which the system comes to rest under
these conditions shall be taken as the indicated force on the
machine.
18. Basis of Verification
18.1 The percent error for forces within the range of forces
of the testing machine shall not exceed 61.0 %. The algebraic
difference between errors of two applications of same force
(repeatability) shall not exceed 1.0 % (see 10.1 and 10.3).
NOTE 11—This means that the report of the verification of a testing
machine will state within what verified range of forces it may be used,
rather than reporting a blanket acceptance or rejection of the machine. In
machines that possess multiple-capacity ranges, the verified range of
forces of each must be stated.
18.2 In no case shall the verified range of forces be stated as
including forces outside the range of forces applied during the
verification test.
18.3 Testing machines may be more or less accurate than
the allowable 61.0 % error, or more or less repeatable than
1.0 %, which are the Practices E 4 verification basis. Buyers/
owners/users or product specification groups might require or
allow larger or smaller error systems. Systems with accuracy
errors larger than 61.0 % or repeatability errors larger than
1.0 % do not comply with Practices E 4.
19. Corrections
19.1 The indicated force of a testing machine that exceeds
the permissible variation shall not be corrected either by
calculation or by the use of a calibration diagram in order to
obtain values within the required permissible variation.
20. Time Interval Between Verifications
20.1 It is recommended that testing machines be verified
annually or more frequently if required. In no case shall the
time interval between verifications exceed 18 months (except
for machines in which a long-time test runs beyond the
18-month period). In such cases, the machine shall be verified
after completion of the test.
20.2 Testing machines shall be verified immediately after
repairs (this includes new or replacement parts, or mechanical
or electrical adjustments) that may in any way affect the
operation of the weighing system or the values displayed.
20.2.1 Examples of new or replacement parts which may
not effect the operation of the weighing system are: printers,
computer monitors, keyboards, and modems.
20.3 Verification is required immediately after a testing
machine is relocated (except for machines designed to be
moved from place to place in normal use), and whenever there
is a reason to doubt the accuracy of the force indicating system,
regardless of the time interval since the last verification.
17. Lever-Type Creep-Rupture Testing Machines
17.1 Lever-type creep-rupture machines, which do not have
a force-indicating device, may be verified using standard
weights or elastic calibration device(s), or both. Weights used
for verification should conform to the requirements of 12.1. In
using an elastic calibration device, the requirements of Sections 14 and 15 must be met as applicable.
17.2 Procedure:
17.2.1 Place the calibration device in the testing machine
and adjust the counterbalance (if the machine is so equipped)
to compensate for the weight of the calibration device.
17.2.2 Connect the lower crosshead of the machine to the
calibration device, and apply forces using standard weights in
increments conforming to the provisions of 10.1.
17.2.3 Since many lever-type creep-rupture machines do not
have a provision for adjustment of the lever ratio or tare, or
both, it may be necessary to determine the “best fit” straight
line through the calibration data, using the least squares
method. By doing this, the actual lever ratio and tare of each
machine can be determined, and thus reduce force errors due to
small variations of lever ratios. Maximum errors should not
exceed the requirements stated in 18.1.
21. Accuracy Assurance Between Verifications
21.1 Some product-testing procedures may require daily,
weekly, or monthly spot checks to ascertain that a testing
machine is capable of producing accurate force values between
the testing machine verifications specified in Section 20.
21.2 Spot checks may be performed on ranges of interest or
at force levels of interest utilizing a calibration device that
complies with Methods A, B, and C as applicable. Elastic
calibration devices must meet Class A requirements of Practice
E 74 for the force level(s) at which the spot checks are made.
6
E 4 – 07
22.1.9 Statement identifying the force-indicating systems
that were verified (for testing machines having more than one
type of indicating system),
22.1.10 Indicated force of the testing machine and applied
force indicated by the calibration device for each run at each
verification force for each force-indicating system verified,
22.1.11 Testing machine error, percent error, and alegebraic
error difference (repeatability) for each force-indicating system
at each force point,
22.1.12 Verified range of forces of each force-indicating
system of the testing machine and associated resolutions(s),
22.1.13 Return to zero reading for each range (see 10.5),
22.1.14 Statement that verification has been performed in
accordance with Practice E 4 – XX. It is recommended that
verification be performed in accordance with the latest published issue of Practice E 4, and
22.1.15 Names of calibration personnel and witnesses (if
required).
21.3 Make spot checks at approximately 20 % and 80 % of
a range unless otherwise agreed upon or stipulated by the
material supplier/user.
21.4 Testing machine error shall not exceed 61.0 % of the
spot check applied forces. Should errors be greater than
61.0 % at any of the spot check force levels, verify the testing
machine immediately (see 20.3).
21.5 Maintain a record of the spot check tests which shall
include the name, serial number, verification date, verification
agency, and the minimum Class A, Practice E 74 value of the
calibrating device(s) used to make spot checks; also include the
name of person making the spot checks.
21.6 The testing machine shall be considered verified up to
the date of the last successful spot check verification (see 21.4),
provided that the testing machine is verified in accordance with
Section 20 on a regular schedule. Otherwise spot checks are
not permitted.
21.7 When spot checks are made, a clear, concise record
must be maintained as agreed upon between the supplier and
the user. The record must also contain documentation of the
regular verification data and schedule.
23. Certificate
23.1 A certificate shall be prepared and signed by the person
in responsible charge of the verification which shall include the
following:
23.1.1 Name of calibrating agency,
23.1.2 Testing machine description and serial number,
23.1.3 Date of certification,
23.1.4 Identification of verified force-indicating systems,
23.1.5 Verified range(s) of force for each force-indicating
system of the testing machine,
23.1.6 Maximum verified range tolerance in percent, and
23.1.7 Serial number, verified range of force, and calibration date of testing devices used for verification.
23.2 The certificate shall be error-free, and contain no
alteration of data, dates, etc.
23.2.1 The certificate shall clearly reference associated
report(s), when supplied.
22. Report
22.1 Prepare a clear and complete report of each verification
of a testing machine which shall include the following:
22.1.1 Name of the calibrating agency,
22.1.2 Date of verification,
22.1.3 Testing machine description, serial number, and location,
22.1.4 Method of verification used,
22.1.5 Serial number and manufacturer of all devices used
for verification,
22.1.6 Statement of how, by whom, and when the calibration of the apparatus used in verifying the testing machine was
made,
22.1.7 Class A range of forces, in accordance with Practice
E 74, for each calibration device,
22.1.8 Temperature of the calibration device and a statement
that computed forces have been temperature corrected as
necessary,
24. Keywords
24.1 calibration; force range; resolution; verification
ANNEX
(Mandatory Information)
A1. VERIFYING THE FORCE MEASURING SYSTEM OUT OF THE TEST MACHINE
A1.1 Significance and Use
A1.1.1 The following are the recognized reasons to perform
a force measuring system verification out of the test machine:
A1.1.1.1 Inadequate spacing within the testing application
load train to allow placement of a force standard.
A1.1.1.2 Physically impossible to apply a primary deadweight force in the compression mode without removal of the
force measuring system.
A1.1.1.3 Test rigs have no reaction frame.
A1.1.2 Verifying the force measuring system out of the
testing machine represents an independent and singular uncertainty component of the total test machine system uncertainty.
Other uncertainty components within the test machine system
exist and need to be identified and quantified to determine, or
verify, the test machine total performance and level of measurement uncertainty. For example, mounting considerations,
7
E 4 – 07
A1.3.2 A minimum of two runs is required per mode
(compression or tension). Rotate the position of the force
transducer by approximately 120 degrees before repeating any
series of forces. During the verification, ensure that the loading
axis is on the center load axis of the force applying apparatus.
Introduce variations or any other factors that are normally
encountered in service.
A1.3.3 Repeatability between the two verification runs shall
be less than or equal to 0.5%. If greater than 0.5%, an
additional third verification run is required. The force transducer shall be rotated by approximately 240 degrees from the
starting position prior to performing the third verification run.
The repeatability between the three verification runs shall be
less than 1.0%. Refer to A1.1.2 to consider all the uncertainty
issues in determining the total test machine system uncertainty.
A1.3.4 The percent error for forces within the verified range
of forces of the testing machine system shall not exceed 6
1.0%.
fixtures, hardness, stiffness, alignment, flatness, and bending
may contribute to the measurement uncertainty of the test
machine.
A1.1.3 Fixture and environment considerations should be
made, to the best degree possible, to simulate the environment
within the testing application (for example, duplicating a
preload).
A1.1.4 Verifying the force measuring system out of the test
machine can be performed:
A1.1.4.1 On-site, removed from the test system, consisting
of a complete force measuring system (force transducer,
conditioning electronics, read-out devices, and cables).
A1.1.4.2 Off-site, removed from the test system, consisting
of a complete for measuring system (force transducer, conditioning electronics, read-out devices, and cables).
A1.2 Calibration Devices
A1.2.1 The force measuring system shall be calibrated by
primary standards or secondary standards used over their Class
A loading range in conjunction with a machine or mechanism
for applying force (see Practice E 74). Several working standards of equal compliance maybe combined and loaded in
parallel to meet special needs for higher capacities.
A1.4 Calculation and Report
A1.4.1 Verification of the force measuring system out of a
test machine shall be clearly noted on the calibration certificate
or report.
A1.3 Verification
A1.3.1 Out of test machine verifications shall include the
force transducer, conditioning electronics, read-out devices,
and cables.
APPENDIXES
(Nonmandatory Information)
X1. DETERMINING RESOLUTION OF THE FORCE INDICATOR
greater than those given in these exceptions, use the ratio
determined. Typical ratios in common usage are 1:1, 1:2, 1:5,
and 1:10.
X1.3.3 Multiply the ratio determined above by the force
represented by one graduation to determine the resolution.
X1.3.4 Apply as constant a force as possible where the
resolution is to be ascertained to minimize the fluctuation of the
force indicator. It is recommended that the fluctuation be no
more than twice the resolution determined in the previous step.
X1.1 The resolution of a testing machine in general is a
complex function of many variables including applied force,
force range, electrical and mechanical components, electrical
and mechanical noise, and software employed, to name a few.
X1.2 A variety of methods may be used to check the
resolution of the system. Some suggested procedures are as
follows.
X1.3 Procedure for Analog Type Force Indicators:
X1.4 Procedure for Non-Auto-Ranging Digital Type Force
Indicators:
X1.4.1 The resolution should be checked at the lowest
verified force in each force range (typically 10% of the force
range).
X1.4.2 Apply a tension or compression force to a specimen
approximately equal to that at which the resolution is to be
ascertained, and slowly change the applied force. Record the
smallest change in force that can be ascertained as the
resolution. Applying the force to a flexible element such as a
spring or an elastomer makes it easier to change the force
slowly.
X1.3.1 Typically these devices are not auto-ranging. The
resolution should be checked at the lowest verified force in
each force range (typically 10 % of the force range).
X1.3.2 Divide the pointer width by the distance between
two adjacent graduation marks at the force where the resolution
is to be ascertained to determine the pointer to graduation ratio.
If the distance between the two adjacent graduation marks is
less than 0.10 in. (2.5 mm) and the ratio is less than 1:5, use 1:5
for the ratio. If the distance between the two adjacent graduation marks is greater than or equal to 0.10 in. (2.5 mm) and the
ratio is less than 1:10, use 1:10 for the ratio. If the ratio is
8
E 4 – 07
X1.5.1.3 A 1000 lbf. capacity machine is to be verified from
5 lbf. up to 1000 lbf. The resolution should be determined at 5,
50, and 500 lbf.
X1.4.3 Next apply as constant a force as possible at the
force where the resolution is to be ascertained to ensure that the
force indicator does not fluctuate by more than twice the
resolution determined in the previous step. If the indicator
fluctuates by more than twice the resolution, the resolution
shall be equal to one-half the range of the fluctuation.
X1.6 Procedure for Machines with Discrete Forces Such as
Certain Hardness Testers and Creep Testers:
X1.6.1 These machines generally incorporate fixed lever
ratios to apply force. The force applied is determined by the
poise applied on the lever multiplied by the lever ratio. They do
not have a resolution as described in the standard. This
procedure ensures that the sensitivity of the machine is
sufficient to apply accurate forces at the lowest verified force
and may be substituted for reporting resolution.
X1.6.2 With an elastic calibration device mounted in the
machine, apply the appropriate poise for the lowest verified
force.
X1.6.3 Gently add weight to the poise approximately equal
to 1/200 of the weight of the poise.
X1.6.4 Ensure that at least one-half of the appropriate
change in force is detected by the elastic calibration device
when the weight is added and when it is gently removed.
X1.5 Procedure for Auto-Ranging Digital Type Force
Indicators:
X1.5.1 This procedure is the same as that for non-autoranging digital force indicators except that the resolution is
checked at the lowest verified force in each decade or at other
forces to ensure that the indicator resolution is 200 times
smaller than the forces. Some examples are as follows.
X1.5.1.1 A 60 000 lbf capacity machine is to be verified
from 240 lbf up to 60 000 lbf. The resolution should be
determined at 240, 2400, and 24 000 lbf.
X1.5.1.2 A 150 000 N capacity machine is to be verified
from 300 N up to 150 000 N. The resolution should be
determined at 300, 3000, and 30 000 N.
X2. IDENTIFYING AND DETERMINING MEASUREMENT UNCERTAINTY COMPONENTS
DURING AN ASTM E 4 VERIFICATION
X2.1 The measurement uncertainty determined using this
appendix is the measurement uncertainty of the errors reported
during verification of a testing machine. It is not the measurement uncertainty of the testing machine or the measurement
uncertainty of test results determined using the testing machine.
environmental conditions allowed. It may be advantageous to evaluate the
measurement uncertainty of the actual force standard used at the actual
force for which the measurement uncertainty of the error of the testing
machine is being determined.
NOTE X2.2—If there are circumstances in which verification is performed under conditions outside of the laboratory’s normal operating
parameters, additional components may need to be considered. For
example, a laboratory may permit a 5°C temperature variation to occur
during verification and has factored this into their measurement uncertainty. When greater temperature variations occur, the uncertainty due to
this increased temperature variation shall be included in the determination
of measurement uncertainty.
NOTE X2.3—A calibration laboratory’s measurement uncertainty is
usually expressed as an expanded uncertainty using a coverage factor of
two. If this is the case, prior to combining it with the other uncertainty
components, divide it by two.
X2.2 Under normal conditions, the measurement uncertainty of the reported errors of a testing machine determined
during an Practices E 4 verification is a combination of three
major components: the measurement uncertainty of the calibration laboratory performing the verification, the uncertainty
component of the resolution of the force indicator of the testing
machine at the force the error is being determined, and the
uncertainty component of the resolution of the force indicator
of the testing machine at zero force.
X2.2.1 The measurement uncertainty of the calibration
laboratory performing the verification is a combination of
factors such as, but not limited to:
X2.2.1.1 The measurement uncertainty of the laboratory’s
force standards per Practice E 74,
X2.2.1.2 Environmental effects such as temperature variations,
X2.2.1.3 Uncertainty in the value used for the local acceleration of gravity at the site where the verification is performed
when using standard weights,
X2.2.1.4 Drift in the force standard,
X2.2.1.5 Measurement uncertainty of the verification of the
force standard, and
X2.2.1.6 Repeatability of the force standard in actual use.
X2.2.2 The uncertainty component due to the resolution of
the force indicator of the testing machine being verified can be
determined by dividing the resolution of the force indicator at
the force where uncertainty is being evaluated by the quantity
of two times the square root of three.
X2.2.3 The uncertainty component due to the resolution of
the force indicator of the testing machine at zero force can be
determined by dividing the resolution of the force indicator at
zero force by the quantity of two times the square root of three.
X2.3 The three major components can be combined by
squaring each component, adding them together, and then
taking the square root of the sum to determine the combined
measurement uncertainty of the error determined for the testing
machine.
X2.4 The expanded measurement uncertainty may then be
determined by multiplying the combined uncertainty by two,
for a confidence level of approximately 95 %.
NOTE X2.1—A laboratory’s measurement uncertainty should be based
on the maximum uncertainty of the force standards used and the worst
9
E 4 – 07
NOTE X2.4—Example: The measurement uncertainty of the error of a
testing machine determined at 2000 N is to be determined. The calibration
laboratory’s measurement uncertainty expanded using a factor of 2 is
0.3 % of applied force. The testing machine’s resolution at 2000 N is 5 N.
The resolution of the testing machine at 0 force is 5 N. The component due
to the calibration laboratory’s measurement uncertainty, uCL is:
0.003 3 2000
uCL 5
53N
2
uZ 5
5
2=3
5 1.4 N
(X2.3)
The combined measurement uncertainty of the error determined at 2000 N, u is:
u 5 =32 1 1.42 1 1.42 5 3.6 N
(X2.1)
(X2.4)
The expanded measurement uncertainty of the error determined at 2000 N, U using a coverage factor of two is:
The component due to the testing machine’s resolution at
2000 N, uR2000 is:
uR2000 5
5
5 1.4 N
2=3
U 5 2 3 3.6 5 7.2 N
(X2.2)
(X2.5)
NOTE X2.5—For additional resources relating to Measurement Uncertainty, refer to the Guide to the Expression of Uncertainty in
Measurement–1995.
The component due to the testing machine’s resolution at
zero force, uZ is:
ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned
in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk
of infringement of such rights, are entirely their own responsibility.
This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and
if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards
and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the
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This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
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(www.astm.org).
10
Lab of Mechanics of Materials
LAB 2 Data Sheet
Reading
Machine
Proving ring
No.
load (lb)
reading (PR)
1
2
3
4
5
6
7
Note:
0
10000
20000
30000
40000
50000
0
the reading
from the
controller
Adjusted
PR
Temp. Adj. PR,
d23
Actulal load Error (lb)
(lb)
Error (%)
Col (F) = Col
(E) * CF
Use ASTM E4 Absolute
stnd.
value of
[Error/Actual error
) = Col G/Col
F
Abs
(Error)
(lb)
1% error 2% error
(lb)
(lb)
0
0
the reading
from the ring
(Actual)
Initial Zero (no) load PR =1
Final Zero (no) load PR =2
Average of Zero (no) load PR =1.5
Calibration Factor (CF) = 138.5
Temperature = 27
oC
Col (D) = Col Col (E) = [apply the
(C) - the
formula for temp.]
average PR
of zero (no)
load
Use ASTM E4
stnd
[MachineActual) = Col
B- Col F
Actual
Load
*1.01
Actual
Load *
1.02
machine load (lb)
0
9000
18500
28000
37800
49000
0
proving ring reading zero error adjust
temperature corrected
(PR)
PR
PR, d23
0
0
0.0
43
43
43.0
128
128
127.9
189
189
188.8
267
267
266.7
334
334
333.6
0
o d23 = dt – 0.00027 (t –
23) dt
machine load vs. actural load
Machine Load, lbf
60000
y = 1.019x + 1079.1
R² = 0.996
50000
40000
30000
20000
10000
0
0
errors vs. 1% vs. 2%
10000
20000
30000
Actual Load, lbf
40000
50000
actulal load
1% error
(lb)
error (lb) error (%) (lb)
0.0
0.0
0.0
5964.1
3035.9
50.9
59.6
17753.6
746.4
4.2
177.5
26214.3
1785.7
6.8
262.1
37032.9
767.1
2.1
370.3
46325.8
2674.2
5.8
463.3
0
0
0
2% error
(lb)
0
-59.6
-177.5
-262.1
-370.3
-463.3
0.0
0
119.3
355.1
524.3
740.7
926.5
0
0
-119.282
-355.0721
-524.2862
-740.6582
-926.5163
0
3500.0
3000.0
2500.0
2000.0
1500.0
1000.0
500.0
0.0
-500.0
50000
-1000.0
-1500.0
0.0
5000.0
10000.0 15000.0 20000.0 25000.0
Series6
1%
-1%
Error (lb)
0
3035.9
746.4
1785.7
767.1
2674.2
0
0
9000 zero error
18500
28000
37800
49000
0
25000.0 30000.0 35000.0 40000.0 45000.0 50000.0
2%
2% error (lb)
2.1
2.1 CF =
2.1
2.1
2.1
2.1
2.1
138.85
Laboratory 2
Calibration of UTM Using Morehouse Proving Ring
This lab will use a Morehouse Proving Ring to check the accuracy of the Tinius & Olsen (T&O)
Universal Testing Machine (UTM).
Read and study the instructions for using Morehouse Proving Rings and the ASTM Standards
on Verification of Testing Machines. Write the procedure as per the ASTM Standards for the
verification of the T&O Universal Testing Machine using the Morehouse Proving Ring.
CAUTION: the maximum indicated load on the machine should not exceed 50,000 pounds.
Determine and/or include the following in the report:
•
type of verification device ( Proving Ring ).
•
capacity of the T&O machine ( 50,000 lb ).
•
capacity of the proving ring ( 100,000 lb ).
•
accuracy of the proving ring calibration
•
table showing ring readings, calibration factor, proving ring load, indicated machine load,
error in pounds, and error in percentage
•
graph of error in pounds vs. proving ring load, show 1% and 2% error lines [will
determine the accuracy level of the UTM]
•
plot of actual load (y-direction) vs. indicated load (x-direction) [linear regression will
provide calibration equation for the UTM]
•
comments on T&O machine based on % of error
An equation for the calibration factor should be derived so that it can be used instead of
reading values from the given graph. Readings will be taken from the Proving Ring at loads of
10k, 20k, 30k, 40k, and 50k. In addition, two no-load readings will be taken (before and after
loading for test).
The report should be written to the instructor in such a way as to meet the following
objectives: 1) determine the magnitude of error in the loads indicated by the machine from 10k
to 50k pounds, 2) determine if the errors are within ranges accepted by ASTM, and 3) prepare a
calibrations chart (graph) of Proving Ring Load vs. Machine Gage Reading Load. Findings
should be discussed as well as recommendations for any action(s) that should be undertaken.
Appendix should contain
1) Calibration data of Testing Equipment
2) Certification of Calibration of Morehouse Proving Ring
Testing Procedure for T&O Testing Machine Verification
1. Make sure all items are off the table and the machine is ready for start-up.
2. Then, Power ON; wait for “clicking” to stop before proceeding any further.
3. Zero the “LOAD” and “UNLOAD” knobs in the lower left-hand side.
4. Turn Pump ON. Allow machine to warm up for about 15 minutes.
5. Switch to Manual Control. Make sure that the Lower Head is in an approachable position.
6. Leave machine in ‘FAST’ mode to Zero table. Switch to ‘SLOW’ for Experiments.
7. Zero all Channels. Verify proper range on loading.
8. Depress “LOAD” and rotate “LOAD” knob to approx. 70 (up to 100 is OK) to raise table to 6”
according to readout. 2” is Fine.
9. Decrease “LOAD” to zero. Then hit STOP.
10. Press and hold “FAST UNLOAD” to allow table to return to neutral position.
11. When pitch of motor changes, then release “FAST UNLOAD” button and allow table to
return to equilibrium.
12. Switch to “SLOW”.
13. Re-Zero all channels and reset Max load with the “CLEAR” button.
14. Place Proving Ring on the table; center is approximately.
15. Obtain “Temperature” and “No-Load” reading. Rotate dial away from reed 4 revolutions.
16. Lower the lower head to close to top of the Proving Ring. .
17. Verify that knobs are at Zero and press “LOAD”.
18. Increase load slowly until Ring contacts lower head. Approx. 20% should be sufficient.
19. Once load starts registering, watch only the load reading.
20. Monitor Proving Ring during loading to ensure reed clearance.
21. Reduce loading rate when the desired load is approached. Null range is at approx. 12 on
the dial.
22. At desired load(s), take reading on the ring dial while another maintains static load.
23. Once all loads have been recorded (from Ring and machine), prepare to unload.
24. To unload, decrease “LOAD” dial to zero. If unloading stops, press “STOP.” Then press
“UNLOAD” and increase “UNLOAD” dial until ring is unloaded.
25. When table movement (down) is observed, press “STOP.”
26. Obtain ‘NO-LOAD’ reading from Proving Ring and Machine.
27. Remove Ring from the machine and return it to the cabinet.
28. Depress “FAST UNLOAD” to allow table to return to neutral position.
29. Shut OFF machine.
Calibration of Testing Equipment
A. General
1. ASTM provides procedures for calibration & verification of equipment
a) ASTM E4 – Standard practices for load verification of testing machines
b) ASTM E83 – Standard method of verification and classification of extensometers.
“Extensometer – an instrument for measuring strain in tension tests.”
c) ASTM E74 – Standard practice of calibration of force – Measuring instrumentations
for verifying the load indication of testing machine.
2. Calibration – The procedure of determining the magnitude of error in the indicated loads.
3. Verification – a calibration to ascertain whether the errors are within a predetermined
range. A certification can be given if errors are acceptable.
4. Load verification must be performed at least every 18months if the machine is to be
used for reporting test data.
a) Always perform after relocation
b) After making a repair
c) Or when accuracy is suspected
B. Verification Methods
1. ASTM E4 allows standard weights, standard weights and lever balances, or elastic
calibration devices.
2. At least 5 verification load levels must be used.
o Minimum is 10% of machine load range.
o Increment between loads must be less than 1/3*(max. load – min. load)
3. Testing machine must be accurate to within ±1% of the actual load for all reading.
4. If deviations are >1%, the machine should be repaired or adjusted to read correctly.
C. Elastic Calibration Devices
1. Two devices are common: elastic proving ring and strain-gage load cell.
2. Proving Ring:
a) Made of flawless forged steel ring and has a deflection gage or dial.
b) Rign has a uniform and repeatable deflection throughout load range.
c) Only used in compression tests.
3. Strain-gage load cells:
a) May be used in either compression or tension tests.
b) Accuracy ≒ ±0.05%
Morehouse Proving Ring
A. General
1. We have Ring No. 4058 with a capacity of 100,000 lb.
2. Ring Reading – the value indicated by the single line index or vernier on the
micrometer dial.
3. Deflection – The difference between the proving ring reading taken under load and
the no load reading.
4. Temp. Correction: The ring calibration factor is dependent on temperature. We have
a curve for 23℃. (Please see the figure attached.)
B. Calculation of Actual Loading at room temperature (for 27℃)
1. Determine dial reading at no load before and after tests, say 1.8 and 1.9
o So average no load reading(NLR) = 1.85
2. Determining dial reading under load specified by machine.
o Say reading = 215 → dt = 215 - 1.85 = 213.15
3. Calculate d23 since Temp at test was 27℃.
o d23 = dt – 0.00027 (t – 23) dt
o d23 = 213.15 – 0.00027(27-23)(213.15) = 212.92
4. From the chart, Calibration factor (CF) corresponding to the number of deflection
division (500) is
o CF = 138.85
5. Actual Load (From the deflection of the ring) = CF * d23 = 138.85 (212.92) =29,564 lb
6. % Error
o (Machine Load – Ring load) / Ring Load * 100
Fall 2018
ENGR 2411 Mechanics of Materials Lab
Section No. 00X (where X=1, 2 or 3)
Lab No.
Lab Title:
Submitted to:
Dr. Hyunju Jeong
Submitted By:
Name:
Student ID:
1
TABLE OF CONTENTS
Title
List of Tables
List of Figures
Abstract
Introduction
Background and Methodology
Results and Discussions
Conclusions and Recommendations
References Cited
Appendix A Raw Data
Appendix B Detail Calculations
Pg. No.
3
4
5
5
5
6
6
6
7
7
2
List of Tables
Table No. and Title
Table 1
Format and Layout of Tables
Pg. No
5
3
List of Figures
Figure No. and Title
Figure 1. Representative graphics embedded within the format of the
paper.
4
Pg. No
6
ABSTRACT
INTRODUCTION
METHODOLOGY
RESULTS AND DISCUSSIONS
5
Figure 2. Representative graphics embedded within the format of the paper.
CONCLUSIONS AND RECOMMENDATIONS
REFERENCES CITED
Brown, D.Z. and Vinson, R.J. (2006). "Stiffness parameters for a strong and colorful
aeolian soil." Geomaterial Characterization (GSP 199), ASCE, Reston/VA: 12-22.
Cimponella, G.R. and Rubertsen, K.P. (1999). "Common problems with conventional
testing." J. Geotechnical & Geoenv. Engr., Vol. 181 (9): 1193-1199.
APPENDIX A
RAW DATA
APPENDIX B
SAMPLE CALCULATIONS
< Attach sample calculations>
6
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