1、Designation: D 4728 06Standard Test Method forRandom Vibration Testing of Shipping Containers1This standard is issued under the fixed designation D 4728; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the random vibration testing offilled shipping units. Such tests may be used to assess theperformance of a con
3、tainer with its interior packing and meansof closure in terms of its ruggedness and the protection that itprovides the contents when subjected to random vibrationinputs.1.2 This test method provides guidance in the developmentand use of vibration data in the testing of shipping containers.NOTE 1Sour
4、ces of supplementary information are listed in the Ref-erence section (110).21.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determ
5、ine the applica-bility of regulatory limitations prior to use. Specific safetyhazard statements are given in Section 6.2. Referenced Documents2.1 ASTM Standards:3D 996 Terminology of Packaging and Distribution Environ-mentsD 4169 Practice for Performance Testing of Shipping Con-tainers and SystemsD
6、4332 Practice for Conditioning Containers, Packages, orPackaging Components for Testing2.2 ISO Standards:ISO 13355 PackagingComplete, filled transport packagesand unit loadsVertical random vibration test43. Terminology3.1 Definitions:3.1.1 GeneralDefinitions for the packaging and distribu-tion envir
7、onments are found in Terminology D 996.3.2 Definitions of Terms Specific to This Standard:3.2.1 bandwidththe difference, in Hz, between the upperand lower limits of a frequency band. For the purposes of thistest method, the bandwidth may be considered equivalent tothe frequency resolution of a spect
8、rum analysis.3.2.2 closed-loopa condition of control where the inputmay be modified over time by the effect of the output orresponse of the system.3.2.3 decibel (dB)ten times the base 10 logarithm of aratio of two power like quantities that is, a PSD. Two PSDlevels that have a ratio of 2.0 differ by
9、 3 dB. Two PSD levelsthat have a ratio of 0.5 differ by 3 dB.3.2.4 equalizationadjustment or correction of the ampli-tude characteristics of an electronic control signal throughout adesired frequency range to maintain a desired vibration outputspectrum and level.3.2.5 equalizerinstrumentation used t
10、o conduct equaliza-tion.3.2.6 mean-squarethe time average of the square of afunction.3.2.7 open loopa condition of control where the input ofa system is preestablished and is not affected by the output orresponse of the system.3.2.8 overall g rmsthe square root of the integral of powerspectral densi
11、ty over the total frequency range.3.2.9 periodic vibrationan oscillation whose waveformrepeats at equal increments of time.3.2.10 power spectral density (PSD)an expression ofrandom vibration in terms of mean-square acceleration per unitof frequency. The units are g2/Hz (g2/cycles/s). Power spectrald
12、ensity is the limit of the mean square amplitude in a givenrectangular band divided by the bandwidth, as the bandwidthapproaches zero.3.2.11 random vibrationan oscillation whose instanta-neous amplitude is not prescribed for any given instant in time.The instantaneous amplitudes of a random vibratio
13、n areprescribed by a probability distribution function, the integral ofwhich over a given amplitude range will give the probablepercentage of time that the amplitude will fall within that1This test method is under the jurisdiction of ASTM Committee D10 onPackaging and is the direct responsibility of
14、 Subcommittee D10.22 on Physical TestMethods.Current edition approved Oct. 1, 2006. Published October 2006. Originallypublished as D-10 Proposal P 186. Last previous edition approved in 2001 asD 4728 01.2The boldface numbers in parentheses refer to the list of references at the end ofthis test metho
15、d.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from International Organization for Standardizat
16、ion, 1 Rue deVarembe8, Case Postale 56, CH-1211, Geneva 20, Switzerland.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.range. Random vibration contains no periodic or quasi-periodicconstituent. If random vibration has instantaneous
17、magnitudesthat occur according to the Gaussian distribution, it is called“Gaussian random vibration.” Gaussian random vibration hasthe property that the rms level is equal to the standarddeviation, or 1 sigma, and that the amplitude will fall within 3sigma, or 3 times the rms level, 99.7 % of the ti
18、me.3.2.12 root-mean-square (rms)the square root of themean-square value. In the exclusive case of a sine wave, therms value is 0.707 times peak value.3.2.13 sigma drive signal clippinga condition where themaximum amplitude of the drive or output signal to a vibrationsystem is limited to a sigma valu
19、e, or multiple of the rms value.For drive clipping at the 3 sigma level, the maximum ampli-tude will not exceed 3 times the rms value.3.2.14 sinusoidal vibrationa periodic oscillation having asinusoidal waveform of only one frequency.3.2.15 spectruma definition of the magnitude of thefrequency compo
20、nents within a specified frequency range.3.2.16 statistical degrees of freedom (DOF)as related toPSD calculation, the degrees of freedom is a measure of thestatistical accuracy of the PSD estimation. The number of DOFis determined by the analysis bandwidth (frequency resolution)and total time of the
21、 sample (determined by frequency resolu-tion and number of averages). It is defined by the formulaDOF=2BT, where B is the analysis bandwidth in Hz, and T isthe total record length in seconds.3.2.17 transfer functionthe dynamic relationship betweenoutput and input. In terms of a vibration system, it
22、is the ratioof output response to a constant input over a defined frequencyrange.4. Significance and Use4.1 Shipping containers are exposed to complex dynamicstresses in the distribution environment. Approximating theactual damage, or lack of damage, experienced in real life mayrequire subjecting th
23、e container and its contents to randomvibration tests. In this way, many product and containerresonances are simultaneously excited.4.2 Resonance buildups during random vibration tests areless intense than during sinusoidal resonance dwell or sweeptests. Therefore, unrealistic fatigue damage due to
24、resonancebuildup is minimized.4.3 Random vibration tests should be based on representa-tive field data. When possible, confidence levels may beimproved by comparing laboratory test results with actual fieldshipment effects. Refer to Practice D 4169 for recommendedrandom vibration tests. (See Appendi
25、x X1 and Appendix X2for related information.)4.4 There is no direct equivalence between random vibra-tion tests and sinusoidal vibration tests. Equivalent testsbetween sine and random, in a general sense, are difficult toestablish due to nonlinearities, damping and product responsecharacteristics.4.
26、5 Vibration exposure affects the shipping container, itsinterior packing, means of closure, and contents. This testallows analysis of the interaction between these components.Design modification to one or all of these components may beused to achieve optimum performance in the shipping environ-ment.
27、4.6 Random vibration tests may be simultaneously per-formed with transient or periodic data to simulate knownstresses of this type, that is, rail joints, pot holes, etc.4.7 Random vibration may be conducted in any axis (verti-cal or horizontal) or in any package orientation. However,different test l
28、evels may be utilized for each axis depending onthe field environment that is to be simulated.5. Apparatus5.1 Vibration Test SystemThe vibration test system(shaker) shall have a vibration table of sufficient strength andrigidity so that the applied vibrations are essentially uniformover the entire t
29、est surface when loaded with the test specimen.The vibration table shall be supported by a mechanism capableof producing single axis vibration inputs at controlled levels ofcontinuously variable amplitude throughout the desired rangeof frequencies. Suitable fixtures and guides to restrict undes-ired
30、 movement of the test specimens shall be provided.5.2 Electronic ControlsControls shall provide the capa-bility of generating vibration system drive inputs necessary toproduce the desired power spectral density at the table surfaceadjacent to the test specimen.5.2.1 Closed LoopAutomatic Equalization
31、A closed loopcontroller is required, which allows the operator to enterdesired PSD data. The controller automatically generatesequalized vibration test system drive signals to achieve thedesired PSD thus maintaining closed loop control. The equal-ized drive signals automatically compensate for speci
32、men andvibration test system characteristics. Typical systems includean analog to digital converter for conditioning feedbacksignals, a digital to analog converter to produce drive signals,a digital processor with real time analysis capability, randomvibration control software programs, a graphics d
33、isplay termi-nal, printer, and a data storage unit.NOTE 2Random vibration systems typically create a drive signal thatfollows the Gaussian distribution. Many systems have a “drive clipping”capability, which is sometimes employed to protect the vibration systemor test specimen from high instantaneous
34、 amplitudes that might causedamage.5.2.2 The digital real time analysis shall provide a minimumof 60 statistical degrees of freedom, and a maximum analysisbandwidth of 2 Hz.5.3 InstrumentationAccelerometers, signal conditioners,analyzers, data display, storage devices, and the control tech-niques de
35、scribed in 5.2 are required to measure and control thePSD levels at the table surface. Instrumentation may also bedesirable for monitoring the response of the test specimen(s).The instrumentation system shall have an accuracy of 65%across the frequency range specified for the test.6. Safety Precauti
36、ons6.1 This test method may produce severe mechanical re-sponses of the test specimen(s). Therefore, fences, barricades,and other restraints must have sufficient strength and must beadequately secured. Operating personnel must remain alert toD4728062the potential hazards and take necessary precautio
37、ns for theirsafety. Stop the test immediately if a dangerous conditionshould develop.7. Test Specimens7.1 The test specimen shall consist of the container asintended for shipment, loaded with the interior packaging andthe actual contents for which it was designed. Blemished orrejected products may b
38、e used if the defect will not affect testresults and if the defect is documented in the report. Dummytest loads are acceptable if testing the actual product might behazardous or cost prohibitive. If a dummy load is used, anassessment must be made, after the test is completed, as towhether or not the
39、 actual test item would have passed or failed.Sensors and transducers should be applied with minimumpossible alteration of the test specimen to obtain data on thecontainer or packaged item.When it is necessary to observe thecontents during the test, holes may be cut in noncritical areasof the contai
40、ner.7.2 Whenever sufficient containers and contents are avail-able, it is highly desirable that replicate tests be conducted toimprove the statistical reliability of the data obtained.8. Calibration and Standardization8.1 The accuracy of instrumentation and test equipmentused to control or monitor t
41、he test parameters should beverified prior to conducting each test to ensure that desired testlevels and tolerances are maintained.8.2 The specified PSD data and resulting RMS accelerationlevel should be based on other test standards, Appendix X1,orderived from actual field measurements or published
42、 PSD datamade on typical transport vehicles under representative condi-tions of speed, load, terrain, road surfaces, etc. Field measure-ments must be accurately recorded with equipment havingadequate frequency response and dynamic range to preventattenuation or noise contamination of the acceleratio
43、n energylevels. Multiple independent field measurements must besampled to assure representative test levels. This data mustthen be reduced to PSD format and equalized for proper controlof the vibration system In the absence of specified PSD data itis recommended that the appropriate profile from Fig
44、 X1.1,beused.8.3 Shaker table input levels to the test specimen providethe only common benchmark for repeatability between varioustest systems. Therefore, control analysis based on monitoringtable motion rather than actual package response is recom-mended. This table feedback signal is generated by
45、 an accel-erometer mounted directly to the table. Accelerometer mount-ing location should be next to the test specimen or directlybelow it on the underside of the table.8.4 The shakers drive signal must be equalized as describedin 5.2 to compensate for test specimen dynamics, the testsystems transfe
46、r function, and the control systems transferfunction.8.4.1 The power spectral density of the random vibrationtest profile shall not deviate from the specified requirements bymore than6 3 dB in any frequency analysis band over theentire test frequency range, except that deviations as large as66 dB wi
47、ll be allowed over a cumulative bandwidth of 10 Hz.In addition, the overall g rms level shall not deviate more than615 % from the specified level during the test.8.4.2 The maximum equalizer analysis bandwidth allowedis 2 Hz and the minimum DOF is 60.8.4.3 The equalizer analysis bandwidth may need to
48、 be lessthan 2 Hz, depending on the slope of the PSD between adjacentbreakpoints. Very steep slopes require smaller bandwidths tomaintain control to 63 dB.8.4.4 If sigma drive signal clipping is used, the clippinglevel used shall not be less than 3.0 sigma.9. Conditioning9.1 Condition test specimens
49、 prior to the test or during thetest, or both, in accordance with the requirements of theapplicable specification. When no conditioning requirementsare given, and the container materials are climatically sensitive,a conditioning atmosphere is recommended (see PracticeD 4332 for standard and special conditions).10. Procedure10.1 Set-up of Test Specimen on Vibration TablePlace theunit(s) to be tested in its normal shipping orientation so that thedesired vibration condition (vertical or horizontal) is transmit-ted to the outer container. The specimen cent
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