ASTMD1596動(dòng)態(tài)緩沖特性測(cè)試

ASTMD1596-97StandardTestMethodforDynamicShockCushioningCharacteristicsofPackagingMaterial包裝材料動(dòng)態(tài)緩沖特性的標(biāo)準(zhǔn)測(cè)試方法ScopeThistestmethodcoversaprocedureforobtainingdynamicshockcushioningcharacteristicsofpackagingmaterialsthroughacceleration-timedataachievedfromdroppingafallingguidedplatenassemblyontoamotionlesssample.Thistestmethoddoesnotaddressanyeffectsorcontributionsofexteriorpackagingassemblies.Thedataacquiredmaybeusedforasinglepointorforuseindevelopingadynamiccushioncurveforthespecificmaterialbeingtested.Suchdatamaybeusedforcomparisonamongdifferentmaterialsatspecificinputconditions,orqualifyingmaterialsagainstperformancespecifications.Cautionshouldbeusedwhenattemptingtocomparedatafromdifferentmethodsorwhenusingsuchdataforpredictingin-packageperformance.Dependingupontheparticularmaterialsofconcern,correlationofsuchdata(fromamongdifferingproceduresorforpredictingin-packageperformance)maybehighlyvariable.Thevaluesstatedininch-poundunitsaretoberegardedasthestandard.TheSIunitsgiveninparenthesesareforinformationonly.ReferencedDocumentsASTMStandards:D996TerminologyofPackagingandDistributionEnvironmentsD4168TestMethodforTransmittedShockCharacteristicsofFoam-in-PlaceCushioningMaterialsD4332PracticeforConditioningContainers,Packages,orPackagingComponentsforTestingE105PracticeforProbabilitySamplingofMaterialsE122PracticeforChoiceofSampleSizetoEstimateaMeasureofQualityforaLotorProcessTerminologyDefinitions-GeneraldefinitionsforpackaginganddistributionenvironmentsarefoundinTerminologyD996.DefinitionsofTermsSpecifictoThisStandard:withrespecttotime,measuredinin./s2(m/s2).displacement-themagnitudeofmovementofabody,point,orsurfacefromafixedreferencepoint,measuredininches(metres).dynamiccushioncurve-agraphicrepresentationofdynamicshockcushioningortransmittedshock(inG”s)overavarietyofstaticloadingconditions(psiorkg/squarem)foraspecificcushioningmaterialthickness(orstructure)ataspecificequivalentfreefalldropheight.SuchrepresentationscanencompasstheaverageresponsereadingsinG”sofanumberofdrops,theaverageofdrops,twotofiveforeachtestphase,orrepresentasingle,specificdropnumberinadropsequence(thatis,firstorthirddropdata).tlpedtofelnrequiredforthedroppingplatentoattainameasuredorgivenimpactvelocity.tltedtyofeplatenifitweretofreefallinavacuumfromaspecifictestdropheight.platendropheight-theactualdropheightofthetestmachineplatenrequiredtoobtainanequivalentfreefallimpactvelocity.reactionmass-amass,consistingoftheimpactsurfaceandanyotherrigidlyattachedmassthatreactsinanopposingmannertotheforcesproducedduringtheimpactofthedroppingplatenontheimpactsurface.staticloading-theappliedmassinpounds(kilograms)dividedbythearea,measuredinsquareinches(metres)towhichthemassisapplied(lbs/in.2orkg/m2).Sometimesreferredtoasstaticstressloading.velocity-therateofchangeofpositionofabodyinaspecifieddirectionwithrespecttotime,measuredininchespersecond(metrepersecond).Symbols:g-symbolfortheaccelerationduetotheeffectsoftheearth”sgravitationalpull.Whilesomewhatvariable,itisusuallyconsideredaconstantofvalue386in./s2or(9.8m/s2).G-symbolforthedimensionlessratiobetweenanaccelerationinlengthpertimesquaredunitsandtheaccelerationofgravityinthesameunits.SummaryofTestMethodAnapparatushavingaguideddroppingplatencapableforceintoatestspecimenplacedonarigidAnaccelerometerrigidlymountedtothedroppingplatenandconnectedtoadataacquisitionsystemrecordstheshockexperienced(acceleration-timehistory)duringtheimpactonthetestspecimen.Bychangingthevariables,suchasimpactvelocity,staticloading(droppingplatenmass),andthenumberoftestimpactsforanygiventest,dynamicshockcushioningcharacteristics(cushioncurves)ofthepackagingmaterialcanbedeveloped.SignificanceandUseDynamiccushioningtestdataobtainedbythistestmethodareapplicabletothecushioningmaterialandnotnecessarilythesameasobtainedinapackage.Inadditiontotheinfluenceofthepackage,thedatacanalsobeaffectedbythespecimenarea,thickness,loadingrate,andotherfactors.ApparatusTestingMachine:Anyguidedverticaldroptestingsystemthatwillproducetestconditionsconformingtotherequirementsspecifiedinthissectionisacceptable.Thesystemshallconsistofarigidflatfaceddroppingplaten,arigidflatimpactsurfacewhosefaceisparalleltothedroppingplatenface.Thedroppingplatenshouldhaveprovisionsforfirmlymountingadditionalmasstoadjustitstotalmasstoadesiredvalue.Itsmassmaybedeterminedbyconsiderationofthestaticloadingoftheitemsthedynamictestissimulating.Varioustestingsystemswillhavedifferentrangesoftestingcapability,bothfordropheightandstaticloadings.Alldroppingplatensareinfluencedbyguidesystemfrictionandairresistance.Thesignificanceoftheseeffectsvarieswiththetypeofapparatusandthemassonthedroppingplaten.Forthisreason,theequivalentfreefallimpactvelocityofthedroppingplatenisequatedtoafreefalldropheightratherthananactualplatendropheight.(Example-Usingtheformulain11.2,a30in.(0.7m)freefallisequatedtoa152in./s(3.9m/s)impactvelocityofthedroppingplaten.)ReactionMass:Thetestingmachineshallbeattachedtoareactionmass.Thereactionmassshallbesufficientlyheavyandrigidsothatnotmorethan2%oftheimpactaccelerationislosttothereactionmasswhileconductingdynamictests.Therigidimpactsurfaceshouldbeinintimatecontactwiththereactionmasssothatthetwobodiesmoveasone(surfacepreparationorgroutingmayberequired).Thisperformancemaybeverifiedbyusingshocksensors,onelocatedonthedroppingplatenandoneontheimpactsurfaceoronthereactionmassimmediatelynexttotheimpactsurfacetomeasuretheaccelerationlevels.Theratioofthemeasuredimpactaccelerationofthereactionmassdividedbythemeasuredaccelerationofthedroppingplatenshallbeequaltoorlessthan2%.6:2.2Asanalternativetomeasuringtheaccelerationlevelofthereactionmassforeachtestcondition,thereactionmassisacceptableifitis50timesthemaximummassofthedroppingplaten.Neitherthedepthnorthewidthofsuchamassshallbelessthanhalfthelength.InstrumentationandShockSensors:Instrumentationisrequiredtomeasuretheimpactvelocitytoanaccuracyof±2%ofthetruevalue.Accelerometers,signalconditions,anddatastorageapparatusarerequiredtomonitoraccelerationversustimehistories.Theinstrumentationsystemsshallhavethefollowingminimumproperties:6.3;2.1Frequencyresponserangefrom2Hzorlesstoatleast1000Hz.Accuracyreadingtobewithin±5%oftheactualvalue.Crossaxissensitivitylessthan5%offullscale,!SamplingThechoiceofsamplingplansformaterialsdependsonthepurposeofthetesting.PracticeE105isrecommended.Thenumberoftestspecimensforeachconditionoftest(forexample,staticloading)dependsonthedesireddegreeofprecisionandtheavailabilityofmaterials.PracticeE122andmanystatisticaltestsprovideexcellentguidanceonthechoiceofsamplesize.Itisrecommendedthatatleastthreereplicatetestspecimensbeusedforeachinitialtestcondition.Then,dependingontheaccuracyanddegreeofcertaintyrequired,thissamplesizemaybeincreasedordecreased.IRandomizationoftestspecimensfromthesampleofmaterialandrandomizationoftheorderoftestingarerecommended.Thismaybeaccomplishedbytheuseofrandomnumbertables,lottery,orotheracceptedprocedureaofrandomization.TestSpecimensTestspecimensshallberightsquareprismsorotherconfigurationasdesiredwiththemaximumlengthandwidthdimensionslessthanthecorrespondingdropplatendimensions.Itisrecommendedthattheminimumlengthandwidthdimensionsbe4by4in.(101.6by101.6mm).Becausepneumaticeffectsandbucklingpropertiesofcushioningmaterialsmaybeinfluencedbysizeandshapeofthespecimen,8by8in.(203.2by203.2mm)specimensarerecommendedwheneverpossible.Whencomparingdatafordifferentcushions,identicallyshapedspecimensshouldbeused.ConditioningMaterials,suchascellulosicmaterials,thatundergochangesinphysicalpropertiesasthetemperatureandtherelativehumiditytowhichtheyareexposedarevariedneedtobepreconditionedinaccordancewithPracticeD4332.Forpolymericcushions,conditiontestspecimenspriortotestforasufficientlengthoftimetoessentiallyachieveandmaintainequilibriuminaccordancewithanyrequirements.Intheabsenceofotherrequirements,usestandardconditioningatmosphereof23±2°C(73.4±3.6°F)and50±2%relativehumidity.ProcedureDimensions-Determinemeasurementsforareacalculationswithanapparatusyieldingvaluesaccurateto0.01in.(0.3mm).specimenasfurnishedorcut,tosizeof8by8in.(203.2by203.2mm)=64in.2(41290mm2);64in.2x0.025psi(41290mm2÷(1106)17.55kg/m2=aloadof1.6lb(0.725kg).)Aftera30sinterval,andwhilethespecimenisstillunder0.025psi(17.55kg/m2)load,measurethethicknesstothenearest0.01in.(0.3mm)atthespecimentopsurfacegeometriccenter.Asanalternativeprocedure,averagethethicknessmeasurementstakenatthefourcornersofthespecimen.Recordthisvalueasthespecimenthickness.Foroddshapesreportwheremeasurementsweretaken.AreaandMass-Measurethetopsurfaceareaofthespecimenwithapparatusyieldingvaluesaccurateto1/32in.or1mm.Measurethemassofthespecimenwithapparatusyieldingvaluesaccurateto30g.10.3DynamicTest-Centerthetestspecimenontheimpactsurfacefaceandpreparethedroppingplatentostrikethecushiononitstopsurfacearea.Thenimpactthespecimenwithaseriesoffivedropsatapr