Designation:D4728–06
Standard Test Method for
Random Vibration Testing of Shipping Containers1
This standard is issued under thefixed designation D4728;the number immediately following the designation indicates the year of original adoption or,in the ca of revision,the year of last revision.A number in parenthes indicates the year of last reapproval.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.
1.Scope
外研社杯1.1This test method covers the random vibration testing of filled shipping units.Such tests may be ud to asss 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.
1.2This test method provides guidance in the development and u of vibration data in the testing of shipping containers. N OTE1—Sources of supplementary information are listed in the Ref-erence ction(1–10).2
1.3This standard does not purport to address all of the safety concerns,if any,associated with its u.It is the responsibility of the ur of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to u.Specific safety hazard statements are given in Section6.
2.Referenced Documents
2.1ASTM Standards:3
D996Terminology of Packaging and Distribution Environ-ments
D4169Practice for Performance Testing of Shipping Con-tainers and Systems
D4332Practice for Conditioning Containers,Packages,or Packaging Components for Testing
服装设计师2.2ISO Standards:
ISO13355Packaging—Complete,filled transport packages and unit loads—Vertical random vibration test43.Terminology
3.1Definitions:
3.1.1General—Definitions for the packaging and distribu-tion environments are found in Terminology D996.
3.2Definitions of Terms Specific to This Standard:
3.2.1bandwidth—the difference,in Hz,between the upper and lower limits of a frequency band.For the purpos of this test method,the bandwidth may be considered equivalent to the frequency resolution of a spectrum analysis.
3.2.2clod-loop—a condition of control where the input may be modified over time by the effect of the output or respon of the system.
3.2.3decibel(dB)—ten times the ba10logarithm of a ratio of two power like quantities that is,a PSD.Two PSD levels that have a ratio of2.0differ by3dB.Two PSD levels that have a ratio of0.5differ by−3dB.
3.2.4equalization—adjustment or correction of the ampli-tude characteristics of an electronic control signal throughout a desired frequency range to maintain a desired vibration output spectrum and level.
只要你说你爱我23.2.5equalizer—instrumentation ud to conduct equaliza-tion.
3.2.6mean-square—the time average of the square of a function.
3.2.7open loop—a condition of control where the input of
a system is preestablished and is not affected by the output or respon of the system.
3.2.8overall g rms—the square root of the integral of power spectral density over the total frequency range.
3.2.9periodic vibration—an oscillation who waveform repeats at equal increments of time.
3.2.10power spectral density(PSD)—an expression of random vibration in terms of mean-square acceleration per unit of frequency.The units are g2/Hz(g2/cycles/s).Power spectral density is the limit of the mean square amplitude in a given rectangular band divided by the bandwidth,as the bandwidth approaches zero.
3.2.11random vibration—an oscillation who instanta-neous amplitude is not prescribed for any given instant in time. The instantaneous amplitudes of a random vibration are prescribed by a probability distribution function,the integral of which over a given amplitude range will give the probable percentage of time that the amplitude will fall within that
1This test method is under the jurisdiction of ASTM Committee D10on
Packaging and is the direct responsibility of Subcommittee D10.22on Physical Test
Methods.
Current edition approved Oct.1,2006.Published October2006.Originally
published as D-10Proposal P186.Last previous edition approved in2001as
D4728–01.
2The boldface numbers in parenthes refer to the list of references at the end of
this test method.
3For referenced ASTM standards,visit the ASTM website,www.astm,or
contact ASTM Customer Service at rvice@astm.For Annual Book of ASTM
Standards volume information,refer to the standard’s Document Summary page on
the ASTM website.
4Available from International Organization for Standardization,1Rue de
Varembe8,Ca Postale56,CH-1211,Geneva20,Switzerland.
Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959,United States.
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range.Random vibration contains no periodic or quasi-periodic constituent.If random vibration has instantaneous magnitudes that occur according to the Gaussian distribution,it is called “Gaussian random vibration.”Gaussian random vibration has the property that the rms level is equal to the standard deviation,or1sigma,and that the amplitude will fall within3 sigma,or3times the rms level,99.7%of the time.
3.2.12root-mean-square(rms)—the square root of the mean-square value.In the exclusive ca of a sine wave,the rms value is0.707times peak value.
3.2.13sigma drive signal clipping—a condition where the maximum amplitude of the drive or output signal to a vibration system is limited to a sigma value,or multiple of the rms value. For drive clipping at the3sigma level,the maximum ampli-tude will not exceed3times the rms value.
3.2.14sinusoidal vibration—a periodic oscillation having a sinusoidal waveform of only one frequency.
3.2.15spectrum—a definition of the magnitude of the frequency components within a specified frequency range. 3.2.16statistical degrees of freedom(DOF)—as related to PSD calculation,the degrees of freedom is a measure of the statistical accuracy of the PSD estimation.The number of D
OF is 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 formula DOF=2BT,where B is the analysis bandwidth in Hz,and T is the total record length in conds.
3.2.17transfer function—the dynamic relationship between output and input.In terms of a vibration system,it is the ratio of output respon to a constant input over a defined frequency range.
4.Significance and U
4.1Shipping containers are expod to complex dynamic stress 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.
4.2Resonance buildups during random vibration tests are less inten than during sinusoidal resonance dwell or sweep tests.Therefore,unrealistic fatigue damage due to resonance buildup is minimized.
龙切尔4.3Random vibration tests should be bad on reprenta-tivefield data.When possible,confidence l
evels may be improved by comparing laboratory test results with actualfield shipment effects.Refer to Practice D4169for recommended random vibration tests.(See Appendix X1and Appendix X2 for related information.)
4.4There is no direct equivalence between random vibra-tion tests and sinusoidal vibration tests.Equivalent tests between sine and random,in a general n,are difficult to establish due to nonlinearities,damping and product respon characteristics.
4.5Vibration exposure affects the shipping container,its interior packing,means of closure,and contents.This test allows analysis of the interaction between the components.Design modification to one or all of the components may be ud to achieve optimum performance in the shipping environ-ment.
4.6Random vibration tests may be simultaneously per-formed with transient or periodic data to simulate known stress of this type,that is,rail joints,pot holes,etc.
4.7Random vibration may be conducted in any axis(verti-cal or horizontal)or in any package orientation.However, different test levels may be utilized for each axis depending on thefield environment that is to be simulated.
5.Apparatus
5.1Vibration Test System—The vibration test system (shaker)shall have a vibration table of sufficient strength and rigidity so that the applied vibrations are esntially uniform over the entire test surface when loaded with the test specimen. The vibration table shall be supported by a mechanism capable of producing single axis vibration inputs at controlled levels of continuously variable amplitude throughout the desired range of frequencies.Suitablefixtures and guides to restrict undes-ired movement of the test specimens shall be provided.
5.2Electronic Controls—Controls shall provide the capa-bility of generating vibration system drive inputs necessary to produce the desired power spectral density at the table surface adjacent to the test specimen.
5.2.1Clod Loop–Automatic Equalization—A clod loop controller is required,which allows the operator to enter desired PSD data.The controller automatically generates equalized vibration test system drive signals to achieve the desired PSD thus maintaining clod loop control.The equal-ized drive signals automatically compensate for specimen and vibration test system characteristics.Typical systems include an analog to digital converter for conditioning feedback signa
ls,a digital to analog converter to produce drive signals, a digital processor with real time analysis capability,random vibration control software programs,a graphics display termi-nal,printer,and a data storage unit.
N OTE2—Random vibration systems typically create a drive signal that follows the Gaussian distribution.Many systems have a“drive clipping”capability,which is sometimes employed to protect the vibration system or test specimen from high instantaneous amplitudes that might cau damage.
5.2.2The digital real time analysis shall provide a minimum of60statistical degrees of freedom,and a maximum analysis bandwidth of2Hz.
5.3Instrumentation—Accelerometers,signal conditioners, analyzers,data display,storage devices,and the control tech-niques described in5.2are required to measure and control the PSD levels at the table surface.Instrumentation may also be desirable for monitoring the respon of the test specimen(s). The instrumentation system shall have an accuracy of65% across the frequency range specified for the test.
6.Safety Precautions
6.1This test method may produce vere mechanical re-spons of the test specimen(s).Therefore,fences,barricades, and other restraints must have sufficient strength and must be adequately cured.Operating personnel must remain alert
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the potential hazards and take necessary precautions for their safety.Stop the test immediately if a dangerous condition should develop.
7.Test Specimens
7.1The test specimen shall consist of the container as intended for shipment,loaded with the interior packaging and the actual contents for which it was designed.Blemished or rejected products may be ud if the defect will not affect test results and if the defect is documented in the report.Dummy test loads are acceptable if testing the actual product might be hazardous or cost prohibitive.If a dummy load is ud,an asssment must be made,after the test is completed,as to whether or not the actual
test item would have pasd or failed. Sensors and transducers should be applied with minimum possible alteration of the test specimen to obtain data on the container or packaged item.When it is necessary to obrve the contents during the test,holes may be cut in noncritical areas of the container.
7.2Whenever sufficient containers and contents are avail-able,it is highly desirable that replicate tests be conducted to improve the statistical reliability of the data obtained.
8.Calibration and Standardization
8.1The accuracy of instrumentation and test equipment ud to control or monitor the test parameters should be verified prior to conducting each test to ensure that desired test levels and tolerances are maintained.
8.2The specified PSD data and resulting RMS acceleration level should be bad on other test standards,Appendix X1,or derived from actualfield measurements or published PSD data made on typical transport vehicles under reprentative condi-tions of speed,load,terrain,road surfaces,etc.Field measure-ments must be accurately recorded with equipment having adequate frequency respon and dynamic range to prevent attenuation or noi contamination of the acceler
ation energy levels.Multiple independentfield measurements must be sampled to assure reprentative test levels.This data must then be reduced to PSD format and equalized for proper control of the vibration system In the abnce of specified PSD data it is recommended that the appropriate profile from Fig.X1.1,be ud.
8.3Shaker table input levels to the test specimen provide the only common benchmark for repeatability between various test systems.Therefore,control analysis bad on monitoring table motion rather than actual package respon is recom-mended.This table feedback signal is generated by an accel-erometer mounted directly to the table.Accelerometer mount-ing location should be next to the test specimen or directly below it on the underside of the table.
8.4The shaker’s drive signal must be equalized as described in5.2to compensate for test specimen dynamics,the test system’s transfer function,and the control system’s transfer function.
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8.4.1The power spectral density of the random vibration test profile shall not deviate from the specified requirements by more than63dB in any frequency analysis band over the entire test frequency range,except that deviations as large as 66dB will be allowed over a cumulative bandwidth of10Hz.In addition,the overall g rms level shall not deviate more than 615%from the specified level during the test.
8.4.2The maximum equalizer analysis bandwidth allowed is2Hz and the minimum DOF is60.
8.4.3The equalizer analysis bandwidth may need to be less than2Hz,depending on the slope of the PSD between adjacent breakpoints.Very steep slopes require smaller bandwidths to maintain control to63dB.
8.4.4If sigma drive signal clipping is ud,the clipping level ud shall not be less than3.0sigma.
9.Conditioning
9.1Condition test specimens prior to the test or during the test,or both,in accordance with the requirements of the applicable specification.When no conditioning requirements are given,and the container materials are climatically nsitive, a conditioning atmosphere is recommended(e Practice D4332for standard and special conditions).
10.Procedure
10.1Set-up of Test Specimen on Vibration Table—Place the unit(s)to be tested in its normal shipping orientation so that the desired vibration condition(vertical or horizontal)is transmit-ted to the outer container.The specimen center of gravity should be as near as practicable to the center of the table.
Unit loads,stacked columns,or single units should be allowed to vibrate freely unless they will actually be curely fastened during shipment,crates on aflatbed trailer for example.When the specimen is not cured to the table,restraining devices should be attached to the vibration table to prevent potential movement of the specimen off the vibration table.Adjust the restraining devices to permit free movement of the specimen of approximately10mm(0.4in.)in any horizontal direction from its centered position.
10.2Start Up Procedure—Provision shall be made that the vibration levels do not overshoot the PSD profile on start up. This is important since random vibration will produce rela-tively large,low frequency displacements in an unpredictable quence.
10.2.1It is recommended that tests be initiated at least6dB below full test level and incremented in one or more sub-quent steps to full test level.This enables the clod loop control system to complete its equalization at lower test levels and provides the operator adequate opportunity to visually verify that the test specimen andfixture are receiving a realistic test,prior to full test level exposure.
10.3Conduct the random vibration test for the length of time stated in the applicable specification,if a
ny,or for a predetermined period,or until a predetermined amount of damage may be detected.The test duration is the time at full test level.Time spent during start up is not included.
10.4Test levels are often incread over the actualfield data to shorten the test time.Any attempt to do so should be done with caution.U of“equivalence”techniques of this type may assume linearity of specimen respon to test input which is,in fact,not likely.
10.5When shipping information becomes available for the test item,the test duration or PSD profile should be
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bad on obrved damage levels.For example,if the labora-tory test does not produce a realistic lev
el of damage,then adjustments should be made.
mrmr11.Report
11.1Report the following information:11.1.1A reference to this test method,
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11.1.2Identification and description of the test specimens,including the container,the interior packaging,the product (give size,weight,and any other pertinent details),and photographs (before and after)of the test items,where pos-sible,
11.1.3If unitized loads are tested,description of the unitized load,the height of the stack,the unitizing method employed,and photographs (before and after)of the test items,where possible,
11.1.4Purpo of the test and the applicable performance specification,if any,
11.1.5Rationale for the random vibration PSD levels’pertinence including a detailed description of the measure-ment and analysis techniques utilized,
11.1.6Details of the test method,test levels analysis band-width,DOF,drive clipping,and durations ud,
11.1.7Verification of compliance with the test method,including a plot of the actual vibration table input PSD,or descriptions of any deviations,
11.1.8Number of replications of each test,
11.1.9Atmospheric conditions to which the specimens were subjected,both prior to test and during test,
11.1.10Any other tests the specimens were subjected to prior to this test,
11.1.11Description of the apparatus and instrumentation ud,
11.1.12Results of the tests,and a comparison between damage levels obrved as a result of the test versus actual damage obrved in transportation,if historical data exists,11.1.13Descriptions and photographs of any damage or deterioration to the containers or their contents as a result of the tests,
11.1.14All significant resonant respons and any obrva-tions that may assist in correct interpretation of results or lead to improvements in design of container,interior packaging or product,and
11.1.15Statement of whether or not the specimens com-plied with the requirements of the applicable specification.12.Precision and Bias
12.1No information is prented about either the precision or bias of this test method for producing damage due to random vibration since the test result is nonquantitative.
13.Keywords
13.1distribution environment;random vibration;shipping container;vibration;vibration control
APPENDIXES
(Nonmandatory Information)X1.SAMPLE PSD TEST PROFILES
X1.1Sample PSD test profiles in Fig.X1.1,Fig.X1.2and
Fig.X1.3are provided for informational purpos only.
They
FIG.X1.1Sample Commercial Transport Vibration Test
Profiles
FIG.X1.2Sample Truck Vibration Test
勺子的英语Profiles
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do not purport to accurately describe a specific transportation mode or distribution environment.The ur of random vibra-tion must verify accuracy and applicability of any data of this type prior to its u.
X1.2Fig.X1.1illustrates that there are relative differences in vibration intensity and frequency content for various types of commercial transportation.
星期三的英语
X1.2.1Fig.X1.1has evolved from a compilation of field measurements made by veral organizations over a period of time.
X1.2.2Whereas the data in Fig.X1.1averages vibration intensities measured under various loading conditions,suspen-sion types,road conditions,weather conditions,travel speeds,etc.,it does not reprent the environment that exists in any specific transportation environment.Exact situations must be verified by the ur of this method.
X1.2.3Transients caud by pot holes,rail joints,takeoff/landing,etc.are not reflected in Fig.X1.1.
X1.2.4The profiles of Fig.X1.1are utilized in Practice D 4169as the Assurance Level II test definitions.
X1.2.5The profiles of Fig.X1.1are prented in Table X1.1.
X1.3Fig.X1.2illustrates the differences that may exist due to truck trailer suspension and trailer loading.The sample test profiles are from Ref (8),and are composites for trucks traveling on interstate expressways at 55mph.
X1.3.1Curve A is for a leaf spring trailer with 20000lb (9072kg)load.
X1.3.2Curve B is for a leaf spring trailer with 40000lb (18144kg)load.
X1.3.3Curve C is for an air cushion trailer with 5000lb (2268kg)load.
X1.3.4Curve D is for an air cushion trailer with 18000lb (8165kg)load.
X1.3.5The profiles of Fig.X1.2are prented in Table X1.2.
X1.4Fig.X1.3provides the test profile from ISO 13355for reference,where it is described as an indicative power spectral density that can be ud to simulate generic (mainly road)transportation.
X1.4.1The profile of Fig.X1.3is prented in Table X1.3
.
FIG.X1.3ISO 13355Vibration Test Profile
TABLE X1.1Fig.X1.1Profiles (Practice D 4169Assurance
Level II)
Truck
Rail
Air
Frequency
Hz Level g 2/Hz Frequency
Hz
Level g 2/Hz Frequency
Hz
Level g 2/Hz 10.0000510.0000120.000240.0120.001120.01160.01500.0011000.01400.001900.0004300j star
0.00001
800.001200
0.00001200
0.00001Overall Level,g rms
0.52
0.29
1.05
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