Standard Test Method for Random Vibration …

1 Designation: D 4728 01 Standard Test Method forRandom Vibration testing of shipping Containers1 This 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 number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or This test Method covers the Random Vibration testing offilled shipping units. Such tests may be used to assess theperformance of a container with its interior packing and meansof closure in terms of its ruggedness and the protection that itprovides the contents when subjected to Random This test Method provides guidance in the developmentand use of Vibration data in the testing of shipping Two alternative Vibration control techniques are de-scribed as A Closed Loop Automatic Equalization( , ) B Open Loop Data Storage Media ( , )

2 NOTE1 Sources of supplementary information are listed in the Ref-erence section(1 10). 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 determine the applica-bility of regulatory limitations prior to safetyhazard statements are given in Section Referenced Standards:D 996 Terminology of Packaging and Distribution Environ-ments3D 4169 Practice for Performance testing of shipping Con-tainers and Systems3D 4332 Practice for Conditioning Containers, Packages orPackaging Components for Standards.

3 ISO 13355 Packaging Complete, filled transport packagesand unit loads Vertical Random Vibration test43. Definitions for the packaging and distribu-tion environments are found in Terminology D of Terms Specific to This the 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 spectrum a condition of control where the inputmay be modified over time by the effect of the output orresponse of the (dB) ten times the base 10 logarithm of aratio of two power like quantities that is, a PSD.

4 Two PSDlevels that have a ratio of differ by 3 dB. Two PSD levelsthat have a ratio of differ by 3 adjustment or correction of the ampli-tude characteristics of an electronic control signal throughout adesired frequency range to maintain a desired Vibration outputspectrum and instrumentation used to conduct the time average of the square of loop a condition of control where the input ofa system is preestablished and is not affected by the output orresponse of the g rms the square root of the integral of powerspectral density over the total frequency

5 Vibration an oscillation whose waveformrepeats at equal increments of 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 spectraldensity is the limit of the mean square amplitude in a givenrectangular band divided by the bandwidth, as the bandwidthapproaches Vibration an oscillation whose instanta-neous amplitude is not prescribed for any given instant in test Method is under the jurisdiction of ASTM Committee D10 onPackaging and is the direct responsibility of Subcommittee on Physical edition approved April 10, 2001.

6 Published June 2001. Originallypublished as D-10 Proposal P 186. Last previous edition D 4728 boldface numbers in parentheses refer to the list of references at the end ofthis test Book of ASTM Standards, Vol from International Organization for Standardization, 1 Rue deVarembe8, Case Postale 56, CH-1211, Geneva 20, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United instantaneous amplitudes of a Random Vibration areprescribed by a probability distribution function.

7 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 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, % of the (rms) the square root of themean-square value.

8 In the exclusive case of a sine wave, therms value is times peak drive signal clipping a condition where themaximum amplitude of the drive or output signal to a vibrationsystem is limited to a sigma value, or multiple of the rms drive clipping at the 3 sigma level, the maximum ampli-tude will not exceed 3 times the rms Vibration a periodic oscillation having asinusoidal waveform of only one a definition of the magnitude of thefrequency components within a specifiedfrequency degrees of freedom (DOF) as related toPSD calculation, the degrees of freedom is a measure of thestatistical accuracy of the PSD estimation.

9 The number of DOFis determined by the analysis bandwidth (frequency resolution)and total time of the sample (determined by frequency resolu-tion and number of averages). It is defined by the formulaDOF=2BT, whereBis the analysis bandwidth in Hz, andTisthe total record length in function the dynamic relationship betweenoutput and input. In terms of a Vibration system, it is the ratioof output response to a constant input over a defined Significance and shipping containers are exposed to complex dynamicstresses in the distribution environment.

10 Approximating theactual damage, or lack of damage, experienced in real life mayrequire subjecting the container and its contents to randomvibration tests. In this way, many product and containerresonances are simultaneously Resonance buildups during Random Vibration tests areless intense than during sinusoidal resonance dwell or sweeptests. Therefore, unrealistic fatigue damage due to resonancebuildup is 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.