1、Designation: D4728 17Standard Test Method forRandom Vibration Testing of Shipping Containers1This standard is issued under the fixed designation D4728; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A nu
2、mber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the random vibration testing offilled shipping units. Such tests may be used to assess theperformance of a conta
3、iner 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 1Source
4、s of supplementary information are listed in theReference section (1-11).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, health and environmental practice
5、s and deter-mine the applicability of regulatory limitations prior to use.Specific safety hazard statements are given in Section 6.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for
6、 theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3D996 Terminology of Packaging and Distribution Environ-mentsD4169 Practice for Performance Testing of S
7、hipping Con-tainers and SystemsD4332 Practice for Conditioning Containers, Packages, orPackaging Components for TestingD7386 Practice for Performance Testing of Packages forSingle Parcel Delivery Systems2.2 ISO Standards:ISO 13355 PackagingComplete, filled transport packagesand unit loadsVertical ra
8、ndom vibration test42.3 ISTA Standards:5ISTA Procedure 1G Packaged-Products 150 lb (68 kg) orLess (Random Vibration)ISTA Procedure 3A Packaged-Products for Parcel DeliverySystem Shipment 70 kg (150 lb) or LessISTA Procedure 3H Products or Packaged-Products in Me-chanically Handled Bulk Transport Con
9、tainers3. Terminology3.1 Definitions:3.1.1 GeneralDefinitions for the packaging and distribu-tion environments are found in Terminology D996.3.2 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 purpose
10、s of thistest method, the bandwidth may be considered equivalent tothe frequency resolution of a spectrum 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 o
11、f aratio of two power like quantities that is, a PSD. Two PSDlevels that have a ratio of 2.0 differ by 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 frequenc
12、y range to maintain a desired vibration outputspectrum and level.3.2.5 equalizerinstrumentation used to conduct equaliza-tion.3.2.6 mean-squarethe time average of the square of afunction.1This test method is under the jurisdiction of ASTM Committee D10 onPackaging and is the direct responsibility of
13、 Subcommittee D10.21 on ShippingContainers and Systems - Application of Performance Test Methods.Current edition approved Sept. 1, 2017. Published September 2017. Originallypublished as D-10 Proposal P 186. Last previous edition approved in 2012 asD4728 01 (2012). DOI: 10.1520/D4728-17.2The boldface
14、 numbers in parentheses refer to the list of references at the end ofthis test method.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
15、 page onthe ASTM website.4Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http:/www.iso.org.5Available from International Safe Transit Association (ISTA), 1400 AbbotRoad, Suite 160, East Lansing, MI 48823-1900, http
16、:/www.ista.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on stand
17、ardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.7 overall g rmsthe square root of the integral of powerspectral density over the tota
18、l frequency range.3.2.8 periodic vibrationan oscillation whose waveformrepeats at equal increments of time.3.2.9 power spectral density (PSD)an expression of ran-dom vibration in terms of mean-square acceleration per unit offrequency. The units are g2/Hz (g2/cycles/s). Power spectraldensity is the l
19、imit of the mean square amplitude in a givenrectangular band divided by the bandwidth, as the bandwidthapproaches zero.3.2.10 random vibrationan oscillation whose instanta-neous amplitude is not prescribed for any given instant in time.The instantaneous amplitudes of a random vibration areprescribed
20、 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 thatrange. Random vibration contains no periodic or quasi-periodicconstituent. If random vibration has instantaneous magnitudesthat
21、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 time.3.2.11 root-
22、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.3.2.12 sigma drive signal clippinga condition where themaximum amplitude of the drive or output signal to a vibrationsystem is limited to a sigma value, or multiple
23、of the rms value.For drive clipping at the 3 sigma level, the maximum ampli-tude will not exceed 3 times the rms value.3.2.13 sinusoidal vibrationa periodic oscillation having asinusoidal waveform of only one frequency.3.2.14 spectruma definition of the magnitude of the fre-quency components within
24、a specified frequency range.3.2.15 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 sample (dete
25、rmined 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.3.2.16 transfer functionthe dynamic relationship betweenoutput and input. In terms of a vibration system, it is the ratioo
26、f 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 the container a
27、nd 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 resonancebuil
28、dup 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 D4169 for recommendedrandom vibration tests. (See Appendix X1 and Appen
29、dix 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.4.5 Vibration ex
30、posure 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.4.6 Random vib
31、ration 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 levels may be u
32、tilized 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 test surface wh
33、en 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 unde-sired movement of t
34、he test specimens shall be provided.5.2 Electronic ControlsControls shall provide the capabil-ity 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 EqualizationA closed loopc
35、ontroller 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 specimen andvibrati
36、on 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 displayterminal
37、, printer, and a data storage unit.NOTE 2Random vibration systems typically create a drive signal thatD4728 172follows the Gaussian distribution. Many systems have a “drive clipping”capability, which is sometimes employed to protect the vibration systemor test specimen from high instantaneous amplit
38、udes 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 described
39、 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 Precautions6.1
40、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 tothe potential hazards and take necessary precautions for theirsaf
41、ety. 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 be used if the d
42、efect 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 actual test it
43、em 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 container.7.2 Wheneve
44、r sufficient containers and contents areavailable, it is highly desirable that replicate tests be conductedto improve the statistical reliability of the data obtained.8. Calibration and Standardization8.1 The accuracy of instrumentation and test equipmentused to control or monitor the test parameter
45、s 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 PSD datamade on
46、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 acceleration energylevels. M
47、ultiple 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 AppendixX1, be used
48、.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 an accel-ero
49、meter 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 transfer 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 d
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1