铝合金5052材料表征.docx

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Chapter3Materialmodelandmaterialaluminiumalloy5052H34preface
,thekeypointofsolvingtheproblemistobuildcorrespondingphysics-,weneedtoconsidertheresponsecharacteristicofthematerialmachanismonconditionofrealimpact(suchasdynamicloading,high-stresscondition,includingprimarydefectsordamage,etc).Bythisway,numerousperformancetestandfull-sizecomponnetcrashtestneedtobeconducted,whichwouldexhaustgreatlaborpowerandphysicalresources,,,highstrainrate(厂1>2x102),,,itcanexpandthespaceofthemodeleffectively,whileobtaincompletematerialparameters.
,mater-ialmachanismmustdescribethematerialchangefromelasticdeformation,elastoplasticdeformation,damage
progession,evolvement,fracture,which
ismulti-step
machanism
,variousstrain
rate,anisotropic
causedby
processinghistory,etcneedtobetake
intoaccountto
considerits
affectionwithconstitutiverelations.
Previously,thisis
aextremely
complexproject,,,andexpandG-T-Nmodelinmicroperspective,whichexplaintheductilefractureofthealuminiumanditsinitiationandevlovementbymachanismofgrowthofvoids,
onfinite-'
aluminiumalloys
incircumstancesof
dynamicloadingwith
large

otherone
contribution
ofFrank'
sresearch
isto
developiterative
algorithm
whichis
aexperiment
combine
with
,whichcanderiveparameterofG-T-Ndamagemodel,,,thiscouldavoidagreatamountofexperimentexpenses,,,withthereducingofstressdegree,shearslipfailurewouldtakethedominentposition,,toadoptesingledamgemodelwouldlimititsapplicability.
Thischapteristryingtoconductmaterialcharacterization,acquirefractureparameterofthe
materialundersimpletension,notchandshearstress,tocarryouttensiletestinconditionofstatic,quasi-staticanddynamicloading,andnumericalsimulation,furthermore,,comparetheprecisionofmodelandsphereofapplicationofthesetwo,todescribethedamageandfracturebehaviourinlargedeformationfrommacrophenomenonanmicromachanism.
Researchofmachanicalpropertytestofmaterialunderstaticanddynamicloading.
.
,itismainlyusedinweldproductioninbearingweightcomponentofcar-body,inactualcollisiondesign,,it'snotenoughformaterialcharacterizationonlyconsideringtosatisfystrengthdemand,therheologicalfutureofmaterialinlargeelasticdeformation,suchasworkhardening,anisotropicandfacturefeaturesofprimarydamageandevolvement,,distribution,andoutsidefactorsofworkingtemperature,,itsorganizationstructureisfixed,buttheworktemperatureandloadingconditionvarieswiththeactualimpactprocess,,thisisaproject,whichneedsparticularcategoryandunifyrequirements.

Inaccordancewiththeactualimpactcondition,weneedtotakestaticanddynamicloadingmachanicalpropertytestinaluminiumalloy5052H43,theexperimentwasdividedintofivegroups,whichissmoothtensiletest,notchtensiletest,doublenotchsheartest,Iosipescusheartest,,,thespecimensarecutfromoriginalplatebyusing(电火花技术),,takingPT1-UT-S1Qasanexampleforexplanation:
Staticuniaxialtesniletestexperimentequipment
Uniaxialsmoothtensiletestisoneofthebasicmachanicalpropertytest,whichismainlyused
-straincurveandfractureparameter,,obtainpracticaldataasmuchaspossible,-displacementdetectsystem,whichusesextend-measurementdisplacement,alsoloadingsensortomeasureload,whichisownedbyInstron1886tensiletestmachine.
Anothersetofmachineisopticaldeformationmeasuresystem,includingstaticcamera,,theshootingangleisseperativelyperpendiculartofrontsideandlateralsideofthespecimens,,withdynamicimagedetectingtoacquirechangesinspecimensection,sowecouldcalculatetheminiumsectionsizeAi,,strainintensileprocess,whichcouldgetstress--displcementismainlyresponsible
forrecordingof
wholecourse
loadingdetectionandelastic
deformationandpartialductiledeformation(beforemaxmiumloading),whiletheopticaldetectingsystemaimatrecordingofdetectionofelasticandductile(beforefracture)deformation.
%correspondtostaticmaxmiumtensileloadatroomtemperature,andfracturestrain&fis73%atfracturing,atthistime,thesedatasegementisundetectablebyusingordinarytensileexperiment,,segmentdataafterneckingcanberepairedifopticaldetectingsystemisused,%.Themeasureproblemofstress-.
Discussion1Relationshipsofstress-strain
2Materialcharacterization
,wecanseethatthedatascaleofoptialdeformationsystemcoveredwider,whilethecomplexityandcostsofthisdetectingsystemisrelativelyhigher.
ofrelativityofanisotropicandstress
conditionSpecimenofsmoothtensiletestis
cutfromthedirectionofvertical
andparalleltotherollingdirection,
theengineeringstress-striancurves
,,tensilestrengthis26Mpahigher,,griansizesofthesufaceislargerthancentergrains().sec-ondly,therearecertaingrainorientationinthecenterofthematerial().Partofthegrainintheaxisalongtherollingdirectionisobviouslylargerthantheothertwoaxises,,therearecertainpreferredorientationintherefinedgrainsaftergraingrowthorrecrytalization,andthesefactorsleadmaterialwithcertainanisotropic.
,thenotchradiusis4mm,,-,largeradditionalstressderived
fromthethicknessandwidthdirection,andthentri-
shearstressorequivalent
Misesstress
thatductile
deformation
neededdecreased,which
wouldlead
toductile

themcroaspect,minish
thenotch
radius,stress
tri-axialityof
componentincreased,stress
concertration
increased
at
thefootofthenotch,ductiltydecreased,%,whichisonly35%oftheengineering

the
experimentanalysis,it'
sclearthatstressconditionisnotrelated
to
yieldingobviously,but
itmattersbadlytolosingeffectiveness
of
fracture.

Caraccidentsmostlyhappensatthevelocityof50Kmperhour,the-1,butthe
impactkineticenergyofmid-*10-,,theappliedtestequipmentareasfollows:1Fallingweightdevicedynamictestisinthescaleof10
2~103s-1onthebasisofsafeimpact
Differentheightsoffallinghammeracquirevariouskineticenergy,,,therehavebeensuchdevicessuchasTinghuauniversity;StateKeyLaboratoryofAuotmotiveSafetyandEnergyandHaribininstituteoftechnologythroughoutthenation.

Thereareverticaltypeandhorizontaltype,itgainsgreatspeedbyexplodedhighenergyballon,thespecimensarefastenedondataacquisitionboardwithpiezoelectricsensor,specimensareimpactedwithhammerloadedwithdifferentmasses,whilerecordtheimpactprocesswithhigh-,,alltheadvanceinsitutearecapableofthistest,suchasCambridge,KaiserslauternuniversityandFraunhoferIWMmachanicalinstitute,whousethisdevicetotestimpactresponsesofcomponents.
(press)polestestdevices
Thismethodisfirstproposedin1914,it',manyresearcherschangedanddevelopedthismethod,inwhichtheimproveddiscretHopkinsondrawpolesbyKoiskyisthemosttypicalone,~104s-1.
ThekeypointofHopkinson',theincidencepoleandtestpoleofthetestdevicearedesignedtobelonger,inordertosepperatetheinfuncefromreflexwa