ASTM D4728-06(2012)
(Test Method)Standard Test Method for Random Vibration Testing of Shipping Containers
Standard Test Method for Random Vibration Testing of Shipping Containers
SIGNIFICANCE AND USE
Shipping containers are exposed to complex dynamic stresses in the distribution environment. Approximating the actual damage, or lack of damage, experienced in real life may require subjecting the container and its contents to random vibration tests. In this way, many product and container resonances are simultaneously excited.
Resonance buildups during random vibration tests are less intense than during sinusoidal resonance dwell or sweep tests. Therefore, unrealistic fatigue damage due to resonance buildup is minimized.
Random vibration tests should be based on representative field data. When possible, confidence levels may be improved by comparing laboratory test results with actual field shipment effects. Refer to Practice D4169 for recommended random vibration tests. (See Appendix X1 and Appendix X2 for related information.)
There is no direct equivalence between random vibration tests and sinusoidal vibration tests. Equivalent tests between sine and random, in a general sense, are difficult to establish due to nonlinearities, damping and product response characteristics.
Vibration exposure affects the shipping container, its interior packing, means of closure, and contents. This test allows analysis of the interaction between these components. Design modification to one or all of these components may be used to achieve optimum performance in the shipping environment.
Random vibration tests may be simultaneously performed with transient or periodic data to simulate known stresses of this type, that is, rail joints, pot holes, etc.
Random vibration may be conducted in any axis (vertical or horizontal) or in any package orientation. However, different test levels may be utilized for each axis depending on the field environment that is to be simulated.
SCOPE
1.1 This test method covers the random vibration testing of filled shipping units. Such tests may be used to assess the performance of a container with its interior packing and means of closure in terms of its ruggedness and the protection that it provides the contents when subjected to random vibration inputs.
1.2 This test method provides guidance in the development and use of vibration data in the testing of shipping containers.
Note 1—Sources of supplementary information are listed in the Reference section (1–10).
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. Specific safety hazard statements are given in Section 6.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D4728 − 06 (Reapproved 2012)
Standard Test Method for
Random Vibration Testing of Shipping Containers
This standard is issued under the fixed designation D4728; 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.
1. Scope 3. Terminology
1.1 This test method covers the random vibration testing of 3.1 Definitions:
filled shipping units. Such tests may be used to assess the 3.1.1 General—Definitions for the packaging and distribu-
performanceofacontainerwithitsinteriorpackingandmeans tion environments are found in Terminology D996.
of closure in terms of its ruggedness and the protection that it
3.2 Definitions of Terms Specific to This Standard:
provides the contents when subjected to random vibration
3.2.1 bandwidth—the difference, in Hz, between the upper
inputs.
and lower limits of a frequency band. For the purposes of this
1.2 This test method provides guidance in the development test method, the bandwidth may be considered equivalent to
and use of vibration data in the testing of shipping containers. the frequency resolution of a spectrum analysis.
3.2.2 closed-loop—a condition of control where the input
NOTE 1—Sources of supplementary information are listed in the
Reference section (1-10). may be modified over time by the effect of the output or
response of the system.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.2.3 decibel (dB)—ten times the base 10 logarithm of a
responsibility of the user of this standard to establish appro-
ratio of two power like quantities that is, a PSD. Two PSD
priate safety and health practices and determine the applica-
levels that have a ratio of 2.0 differ by 3 dB. Two PSD levels
bility of regulatory limitations prior to use. Specific safety
that have a ratio of 0.5 differ by −3 dB.
hazard statements are given in Section 6.
3.2.4 equalization—adjustment or correction of the ampli-
tudecharacteristicsofanelectroniccontrolsignalthroughouta
2. Referenced Documents
desired frequency range to maintain a desired vibration output
2.1 ASTM Standards: spectrum and level.
D996Terminology of Packaging and Distribution Environ-
3.2.5 equalizer—instrumentation used to conduct equaliza-
ments
tion.
D4169Practice for Performance Testing of Shipping Con-
3.2.6 mean-square—the time average of the square of a
tainers and Systems
function.
D4332Practice for Conditioning Containers, Packages, or
3.2.7 open loop—aconditionofcontrolwheretheinputofa
Packaging Components for Testing
system is preestablished and is not affected by the output or
2.2 ISO Standards:
response of the system.
ISO 13355Packaging—Complete, filled transport packages
3.2.8 overall g rms—thesquarerootoftheintegralofpower
and unit loads—Vertical random vibration test
spectral density over the total frequency range.
3.2.9 periodic vibration—an oscillation whose waveform
repeats at equal increments of time.
This test method is under the jurisdiction of ASTM Committee D10 on
Packaging and is the direct responsibility of Subcommittee D10.21 on Shipping
3.2.10 power spectral density (PSD)—an expression of
Containers and Systems - Application of Performance Test Methods.
randomvibrationintermsofmean-squareaccelerationperunit
Current edition approved April 1, 2012. Published May 2012. Originally
2 2
of frequency. The units are g /Hz (g /cycles/s). Power spectral
published as D-10 Proposal P186. Last previous edition approved in 2006 as
D4728– 01 (2006). DOI: 10.1520/D4728-06R12. density is the limit of the mean square amplitude in a given
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
rectangular band divided by the bandwidth, as the bandwidth
this test method.
approaches zero.
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
3.2.11 random vibration—an oscillation whose instanta-
Standards volume information, refer to the standard’s Document Summary page on
neousamplitudeisnotprescribedforanygiveninstantintime.
the ASTM website.
The instantaneous amplitudes of a random vibration are
Available from International Organization for Standardization (ISO), 1, ch. de
la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http://www.iso.org. prescribedbyaprobabilitydistributionfunction,theintegralof
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4728 − 06 (2012)
which over a given amplitude range will give the probable 4.5 Vibration exposure affects the shipping container, its
percentage of time that the amplitude will fall within that interior packing, means of closure, and contents. This test
range.Randomvibrationcontainsnoperiodicorquasi-periodic
allows analysis of the interaction between these components.
constituent. If random vibration has instantaneous magnitudes Design modification to one or all of these components may be
that occur according to the Gaussian distribution, it is called
usedtoachieveoptimumperformanceintheshippingenviron-
“Gaussian random vibration.” Gaussian random vibration has
ment.
the property that the rms level is equal to the standard
4.6 Random vibration tests may be simultaneously per-
deviation, or 1 sigma, and that the amplitude will fall within 3
formed with transient or periodic data to simulate known
sigma, or 3 times the rms level, 99.7% of the time.
stresses of this type, that is, rail joints, pot holes, etc.
3.2.12 root-mean-square (rms)—the square root of the
4.7 Random vibration may be conducted in any axis (verti-
mean-square value. In the exclusive case of a sine wave, the
cal or horizontal) or in any package orientation. However,
rms value is 0.707 times peak value.
different test levels may be utilized for each axis depending on
3.2.13 sigma drive signal clipping—a condition where the
the field environment that is to be simulated.
maximumamplitudeofthedriveoroutputsignaltoavibration
systemislimitedtoasigmavalue,ormultipleofthermsvalue.
5. Apparatus
For drive clipping at the 3 sigma level, the maximum ampli-
tude will not exceed 3 times the rms value.
5.1 Vibration Test System—The vibration test system
3.2.14 sinusoidal vibration—a periodic oscillation having a
(shaker) shall have a vibration table of sufficient strength and
sinusoidal waveform of only one frequency.
rigidity so that the applied vibrations are essentially uniform
overtheentiretestsurfacewhenloadedwiththetestspecimen.
3.2.15 spectrum—a definition of the magnitude of the fre-
Thevibrationtableshallbesupportedbyamechanismcapable
quency components within a specified frequency range.
ofproducingsingleaxisvibrationinputsatcontrolledlevelsof
3.2.16 statistical degrees of freedom (DOF)—as related to
continuously variable amplitude throughout the desired range
PSD calculation, the degrees of freedom is a measure of the
of frequencies. Suitable fixtures and guides to restrict unde-
statisticalaccuracyofthePSDestimation.ThenumberofDOF
sired movement of the test specimens shall be provided.
isdeterminedbytheanalysisbandwidth(frequencyresolution)
and total time of the sample (determined by frequency resolu-
5.2 Electronic Controls—Controlsshallprovidethecapabil-
tion and number of averages). It is defined by the formula
ity of generating vibration system drive inputs necessary to
DOF=2BT, where Bis the analysis bandwidth in Hz, and Tis
produce the desired power spectral density at the table surface
the total record length in seconds.
adjacent to the test specimen.
3.2.17 transfer function—the dynamic relationship between
5.2.1 Closed Loop–Automatic Equalization—A closed loop
output and input. In terms of a vibration system, it is the ratio
controller is required, which allows the operator to enter
ofoutputresponsetoaconstantinputoveradefinedfrequency
desired PSD data. The controller automatically generates
range.
equalized vibration test system drive signals to achieve the
desired PSD thus maintaining closed loop control. The equal-
4. Significance and Use
ized drive signals automatically compensate for specimen and
4.1 Shipping containers are exposed to complex dynamic vibration test system characteristics. Typical systems include
stresses in the distribution environment. Approximating the an analog to digital converter for conditioning feedback
actualdamage,orlackofdamage,experiencedinreallifemay signals, a digital to analog converter to produce drive signals,
require subjecting the container and its contents to random a digital processor with real time analysis capability, random
vibration tests. In this way, many product and container
vibration control software programs, a graphics display
resonances are simultaneously excited.
terminal, printer, and a data storage unit.
4.2 Resonance buildups during random vibration tests are
NOTE 2—Random vibration systems typically create a drive signal that
less intense than during sinusoidal resonance dwell or sweep
follows the Gaussian distribution. Many systems have a “drive clipping”
tests. Therefore, unrealistic fatigue damage due to resonance capability, which is sometimes employed to protect the vibration system
or test specimen from high instantaneous amplitudes that might cause
buildup is minimized.
damage.
4.3 Random vibration tests should be based on representa-
5.2.2 Thedigitalrealtimeanalysisshallprovideaminimum
tive field data. When possible, confidence levels may be
of 60 statistical degrees of freedom, and a maximum analysis
improvedbycomparinglaboratorytestresultswithactualfield
bandwidth of 2 Hz.
shipment effects. Refer to Practice D4169 for recommended
random vibration tests. (See Appendix X1 and Appendix X2
5.3 Instrumentation—Accelerometers, signal conditioners,
for related information.)
analyzers, data display, storage devices, and the control tech-
4.4 There is no direct equivalence between random vibra- niquesdescribedin5.2arerequiredtomeasureandcontrolthe
PSD levels at the table surface. Instrumentation may also be
tion tests and sinusoidal vibration tests. Equivalent tests
between sine and random, in a general sense, are difficult to desirable for monitoring the response of the test specimen(s).
establish due to nonlinearities, damping and product response The instrumentation system shall have an accuracy of 65%
characteristics. across the frequency range specified for the test.
D4728 − 06 (2012)
6. Safety Precautions 8.4 Theshaker’sdrivesignalmustbeequalizedasdescribed
in 5.2 to compensate for test specimen dynamics, the test
6.1 This test method may produce severe mechanical re-
system’s transfer function, and the control system’s transfer
sponses of the test specimen(s). Therefore, fences, barricades,
function.
and other restraints must have sufficient strength and must be
8.4.1 The power spectral density of the random vibration
adequately secured. Operating personnel must remain alert to
testprofileshallnotdeviatefromthespecifiedrequirementsby
the potential hazards and take necessary precautions for their
more than6 3 dB in any frequency analysis band over the
safety. Stop the test immediately if a dangerous condition
entire test frequency range, except that deviations as large as
should develop.
66 dB will be allowed over a cumulative bandwidth of 10 Hz.
In addition, the overall g rms level shall not deviate more than
7. Test Specimens
615% from the specified level during the test.
8.4.2 The maximum equalizer analysis bandwidth allowed
7.1 The test specimen shall consist of the container as
is 2 Hz and the minimum DOF is 60.
intended for shipment, loaded with the interior packaging and
8.4.3 The equalizer analysis bandwidth may need to be less
the actual contents for which it was designed. Blemished or
than2Hz,dependingontheslopeofthePSDbetweenadjacent
rejected products may be used if the defect will not affect test
breakpoints. Very steep slopes require smaller bandwidths to
results and if the defect is documented in the report. Dummy
maintain control to 63 dB.
test loads are acceptable if testing the actual product might be
8.4.4 If sigma drive signal clipping is used, the clipping
hazardous or cost prohibitive. If a dummy load is used, an
level used shall not be less than 3.0 sigma.
assessment must be made, after the test is completed, as to
whetherornottheactualtestitemwouldhavepassedorfailed.
9. Conditioning
Sensors and transducers should be applied with minimum
9.1 Condition test specimens prior to the test or during the
possible alteration of the test specimen to obtain data on the
test, or both, in accordance with the requirements of the
containerorpackageditem.Whenitisnecessarytoobservethe
applicable specification. When no conditioning requirements
contents during the test, holes may be cut in noncritical areas
aregiven,andthecontainermaterialsareclimaticallysensitive,
of the container.
a conditioning atmosphere is recommended (see Practice
7.2 Whenever sufficient containers and contents are D4332 for standard and special conditions).
available,itishighlydesirablethatreplicatetestsbeconducted
10. Procedure
to improve the statistical reliability of the data obtained.
10.1 Set-up of Test Specimen on Vibration Table—Place the
8. Calibration and Standardization
unit(s)tobetestedinitsnormalshippingorientationsothatthe
desired vibration condition (vertical or horizontal) is transmit-
8.1 The accuracy of instrumentation and test equipment
ted to the outer container. The specimen center of gravity
used to control or monitor the test parameters should be
should be as near as practicable to the center of the table. Unit
verifiedpriortoconductingeachtesttoensurethatdesiredtest
loads, stacked columns, or single units should be allowed to
levels and tolerances are maintained.
vibrate freely unless they will actually be securely fastened
8.2 The specified PSD data and resulting RMS acceleration during shipment, crates on a flatbed trailer for example. When
level should be based on other test standards, Appendix X1,or the specimen is not secured to the table, restraining devices
derived from actual field measurements or published PSD data should be attached to the vibration table to prevent potential
made on typical transport vehicles under representative condi- movement of the specimen off the vibration table. Adjust the
tions of speed, load, terrain, road surfaces, etc. Field measure- restrainingdevicestopermitfreemovementofthespecimenof
approximately10mm(0.4in.)inanyhorizontaldirectionfrom
ments must
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