关闭

关闭

封号提示

内容

首页 UDEC.ppt

UDEC.ppt

UDEC.ppt

上传者: wwwww 2013-12-25 评分 3 0 44 6 200 暂无简介 简介 举报

简介:本文档为《UDECppt》,可适用于高等教育领域,主题内容包含UDECDECShortCourseUDECDECShortCourseItascaSoftwareTrainingCourseTongjiUniv符等。

UDECDECShortCourseUDECDECShortCourseItascaSoftwareTrainingCourseTongjiUniversityShanghai,ChinaOctober,PeterCundall,YanhuiHanRogerHartItascaConsultingGroup,IncTrainingScheduleOctober,(afternoon)TrainingScheduleOctober,(afternoon)::OverviewofUDECDECFeaturesandCapabilitiesOverviewofcapabilitiesingeoengineeringNewfeaturesinUDECandDECTheoreticalbasis::Break::RunningModelsinUDECMenudrivenversuscommanddrivenoperationSimpletutorialWhatisUDECUDECisaDEMcodethatallowsthesimulationoftheinteractionofblocksThismaybeajointedrockmass,amasonrywall,oranymaterialwherethemodeofdisplacementmayoccuralongpreexistingplanesofweaknessordiscontinuityAnygeometrycanberepresented,andtheboundaryconditionsarequitegeneralUDECalsosimulatesthebehavioroftheintactmaterialbetweentheplanesofweaknessasanonlinearcontinuum,usingthegeneralizedfinitedifferencemethod(arbitraryelementshapes),knownasthefinitevolumemethodUDECsolvesthefulldynamicequationsofmotionevenforquasistaticproblemsThishasadvantagesforproblemsthatinvolvephysicalinstability,suchascollapse,aswillbeexplainedlaterTomodelthe“static”responseofasystem,dampingisusedtoabsorbkineticenergyWhatisUDECUDECUDECDiscontinuousmediummodeledasanassemblageofconvexorconcaveblocksblocksmayberigidordeformableDiscontinuitiestreatedasboundaryconditionsbetweenblocksMotionalongdiscontinuitiesgovernedbylinearandnonlinearforcedisplacementrelationsformovementsinboththenormalandsheardirectionManybuiltinblockandjointconstitutivemodelsthatarerepresentativeofgeologic,orsimilar,materialsoptionaluserwrittenmodelsPlanestrain,planestressandaxisymmetricgeometrymodesStructuralelementmodelsforrockstructureinteraction–cables,piles,beams,liners,shotcrete,soilreinforcement,etcStaticanddynamicanalysiscapabilitiesTransientandsteadystatefluidflowinjointsViscoelasticandviscoplastic(creep)modelsThermalanalysiscapability,withcouplingtosolidandfluid…isbestsuitedtomodelingdiscontinuousmaterials(containingmanyintersectingdiscontinuities)thatexhibitnonlinearbehaviorInparticular,itfeatures:DECDECsimilartoUDEC,butinthreedimensionscontainsthesamefeaturesaslistedforUDECModelofarchdamusingfiniteelementblocksNewFeaturesinUDECGraphicaluserinterfaceFactorofsafetycalculationbasedontheshearstrengthreductionmethodUserdefinedzoneandjointconstitutivemodelsMixeddiscretizationtoprovidemoreaccuracyforplasticityanalysisTwophaseflowinjointsNetworkkeylicenseversionNewFeatureinUDECReleasedinOctoberImprovedandrestructuredgraphicaluserinterface(availableatnoadditionalchargetocurrentVersionowners)PlannedNewFeaturesinUDECGeneric“virtualmodel”generationtooltofacilitatemodelcreationSpeedupofdoubleprecisionversionbyconvertingtoIntelFortrancompilerMixedDiscretizationschemefortriangularelements“NodalMixedDiscretization”toprovidemoreaccuratesolutionofplasticityproblemsusingtriangulargridsRockboltelementstosimulaterockreinforcementincludingtensilerupture,strainsofteningbehaviorofgroutandeffectofchangingconfiningstressHelpFilecontainingCommandReference,FISHReferenceandExampleApplicationsEstimatedrelease:midNewFeaturesinDECAcceleratedinteractivegraphics(OpenGLbasedplotting)withnewgraphicalstructureNewMixedDiscretizationschemefortetrahedralelements“NodalMixedDiscretization”providesmoreaccuratesolutionofplasticityproblemsusingtetrahedralgridsbitversionFactorofSafetycalculationmodeImprovementstouserdefinedconstitutivemodelsandadditionofuserdefinedjointconstitutivemodelsImprovementstostructuralelementlogicincludinginstallationattunnelintersectionsHelpFilecontainingCommandReference,FISHReferenceandExampleApplicationsNewPGENinterfaceImprovedFISHlanguageReleasedinJanuaryTheExplicitDynamicSolutionSchemeandtheDistinctElementMethodinUDECDECTheExplicitDynamicSolutionSchemeandtheDistinctElementMethodinUDECDECDEMDefinitionsDEMDefinitionsThename“DiscreteElementMethod”(DEM)shouldbeappliedtoamethodonlyifit*:allowsfinitedisplacementsandrotationsofdiscretebodiesincludingcompletedetachmentrecognizesnewinteractions(contact)automaticallyasthecalculationprogressesAdiscreteelementcodewillembodyanefficientalgorithmfordetectingandclassifyingcontactsItwillmaintainadatastructureandmemoryallocationschemethatcanhandlemanyhundredsorthousandsofdiscontinuitiesorcontactsThename“DistinctElementMethod”isusedforaDEMthatusesanexplicitdynamicsolutiontoNewton’slawsofmotion*Cundall,PA,andRDHart”NumericalModelingofDiscontinua,”EngineeringComputations,(),()Finiteelementcodesformodeling“discontinua”areoftenmodifiedcontinuumprograms,whichcannothandlegeneralinteractiongeometry(egmanyintersectingjoints)TheirefficiencymaydegeneratedrasticallywhenconnectionsarebrokenrepeatedlyTypesofDiscreteElementMethodsforDiscontinuumAnalysisTypesofDiscreteElementMethodsforDiscontinuumAnalysisDistinctElementUseexplicittimemarchingschemetosolveequationsofmotiondirectlyBodiesmayberigidordeformable,contactsaredeformableModalMethodsSimilartodistinctelementmethodinthecaseofrigidblocksFordeformablebodies,modalsuperpositionisusedsononlinearityisdifficulttoimplementDiscontinuousDeformationAnalysisAssumescontactsarerigidbodiesandbodiesmayberigidordeformableNopenetrationisachievedbyiterationMomentumExchangeMethodsAssumeboththecontactsandbodiestoberigidMomentumisexchangedbetweentwocontactingbodiesduringcollisionCanrepresentfrictionslidingDistinctElementMethodDistinctElementMethodThreeaspectsGeometryContactmechanicsSolidbodymechanicsDistinctElementMethodDistinctElementMethodGeometrySpecificationofshapesinanddimensionsInteractionofpairsofcontactingblocksorparticlesIdentificationofcontactcharacterbetweenblocksDistinctElementMethodDistinctElementMethodSpecificationofshapesinanddimensionsdimensions–PFCdisksspheresdimensions–UDECarbitrarypolygons–convexandconcave–withroundedcornersdimensions–DECarbitrarypolyhedra–concavebodiesareconstructedofseveralconvexbodiesattachedtogetherDistinctElementMethodDistinctElementMethodInteractionofpairsofcontactingblocksorparticlesIfweattempttoidentifyneighboringblocksbyanexhaustivescan(ieeachblocktestedagainsteachother),thenthesearchtimeisproportionaltoNwhereNisthenumberofblocksTwomethodstoreducesearchtime:Cellmapping,usedinUDECDECCirculatingdatastructure,thatmimicsthetopologyofthesystemasusedinUDECCellmappingCellmappingThesolutionspaceiscoveredbyrectangularcellsEachblockdepositsamarkerinallthecellsthatitoverlaps–thisprocesstakesNproportionaltimeEachblockcanfindallofitsneighborsbylookinginjustthosecellsthatitoverlapsthisprocessisalsoNproportional,ifthecellsizeisofasimilarordertotheblocksizeCirculatingdatastructureCirculatingdatastructureLinkedliststhatdescribeblockboundariesalsotraceoutthevoidspacesautomaticallyAblockneedsonlytosearchitslocalvoidspacestofinditsneighborsThisschemebreaksdownifmanyblocksbecomedisconnected,butitiswellsuitedtomodelfluidflowinjointscloseddomaincanrestrictsearchtothecloseddomain–anynewcontactsmustbethereDistinctElementMethodDistinctElementMethodIdentificationofcontactcharacterbetweenblocksWeneedtoknow:typeofcontact(egcornertocorner,cornertoedge,etc)directionofnormaltoslidingdirectiongapbetweenblocks,orcontactoverlapBlockJointunusBlockusunInitialPositionofblockxyblockcentroidContactBetweentwoRigidBlocksAcontactiscreatedateachcornerinteractingwithacorneroredgeofanopposingblockRoundedCornersinUDECCornerroundingschemewithconstantlengthdrdd=rd>>rrdd=distancetothecornerr=radiusoftheroundedcornerrdd=rdrd>>rCornerroundingschemewithconstantradiusr,showingthatsmallanglesinthecornerleadstolargedistancesdDefinitionofcontactnormalRoundedcornertoedgecontactRoundedcornertocornercontactLLLElementNodesCornerEdgecontactsL,L,LLengthsassociatedtothecontactsContactsandDomainsbetweenTwoDeformableBlocksDDDDDomainsBLOCKBLOCKInteractionoftwosquaresInteractionoftwosquaresMaximumnumberoftestscornersedgescorneredgecorneredgecorneredgeInteractionoftwocubesInteractionoftwocubesfacesedgescornersfaceedgecornerfaceedgecornerfaceedgecornerTotalfacecorneredgeModesofcontactsModesofcontactscornercorneredgeedgecornerfacecorneredgeModesofcontactsModesofcontactsfacefaceedgeface“Commonplane”logic“Commonplane”logicAlgorithmexecutedinparallelwithmechanicalcalculation:“maximizethegapbetweenthecommonplane(cp)andtheclosestvertex”cp“Commonplane”logic“Commonplane”logicIfweassumeacpcanbefound,blocksareconvexthentestforcontactsiseasytestcornersofbothblocksforcontactwithcp(dotproducts)iftestforbothblocksarepositivethenblocksaretouchingdetermininggapiseasysumofmindistancesfromeachblock’scornertocpcontactnormalisthenormalofthecpisalwaysdefinedCommonplanelogicCommonplanelogicWhataboutassumptionsUsethealgorithm“maximizethesmallestgapbetweeneachblock(ofacontactpair)andtheplane”Constructconcaveblocksfromseveralconvexblocks(the“join”doesnotexist,asfarasphysicsisconcerned)shift,thenrotationCommonplanelogicCommonplanelogicModesofcontactcanbefoundeasilywithcontactplanelogic“countthenumberofcornersthattouchthecommonplane”modeofcontactisdeterminedbycounts:eg=“cornerface”note:”touch”impliesgap<BlockAcorneredgefaceBlockBcorneredgefaceDistinctElementMethodDistinctElementMethodContactmechanicsAllcontactsareassumedtobe“soft”iecontactforcesaredirectlyrelatedtothedeformationsor“overlaps”atcontactsForpointcontact,HertzMindlincontactlawscanbeusedForedgetoedgecontact,suchasrockjoints,variousconstitutivelawscanbeused–eg,elasticCoulombslipUDECDECalsohavethe”continuouslyyielding”model,whichemployscontinuousfunctionsfortheforcedisplacementrelationsThereisalsointernaldamageaccumulationDistinctElementMethodDistinctElementMethodSolidbodymechanicsTherearetwoformulationsRigidbodytranslationandrotationDeformablebodymechanicsRigidbodytranslationandrotationRigidbodytranslationandrotationIfmostofthemovementinasystemtakesplaceinadiscontinuousway(egsliding,opening,relativerotation,interlocking),thenthebodiesmaybeassumedtoberigidDistinctElementMethodDeformablebodymechanicsDeformablebodymechanicsIfthereisappreciabledeformationoftheintactmaterial,comparedtodiscontinuousmotion,thenthebodiesmustbetakenasdeformableDistinctElementMethodDeformablebodymechanicsDeformablebodymechanicsInordertomodeldeformableblocks,thereareautomaticgenerators–inUDECtodivideabodyintotriangles,andinDECtodividebodiesintotetrahedraThefinitedifferenceformulationfortheseinternalelementsisidenticaltothatforFLACSeverallinearandnonlinearconstitutivemodelscanbeusedintheinternalelementsDistinctElementMethodTheExplicitDynamicSolutionSchemeappliedwiththeDistinctElementMethodTheExplicitDynamicSolutionSchemeappliedwiththeDistinctElementMethodBasisoftheSolutionSchemeUDECandDECsolvethefulldynamicequationsofmotionevenforquasistaticproblemsThishasadvantagesforproblemsthatinvolvephysicalinstability,suchascollapseTomodelthe“static”responseofasystem,arelaxationschemeisusedinwhichdampingabsorbskineticenergyThisapproachcanmodelcollapseproblemsinamorerealisticandefficientmannerthanotherschemes,eg,matrixsolutionmethodsBasisoftheSolutionSchememovieOverviewofDEMexplicit,dynamicsolutionschemeTheformulationisverysimpleForexample,foraballimpactingawall,massOnetimestep,unknownsknowns(allcontacts,ingeneral)(allparticles,ingeneral)Fulldynamicequations(integrationofNewton’sndlaw)ExplicitsolutionschemeThreeconsequencesofthisformulationareasfollows…(centraldifference–ndorderaccurate)Treatingeachbodyasdiscrete(DEM)allowsdiscontinuousmaterial(suchasarockmass)tobemodeledeasilyFulldynamicequationsofmotionallowtheevolutionofunstablesystemstobesimulatedrealisticallyExplicitsolutionschememakesthetaskofhandlingnonlinearitytrivialExamplesofnonlinearitiesare:(a)contactmakingbreaking(b)softeningmaterialbehavior(rocklike)eg,INPUTOUTPUTTheexplicitschemeusesatimestepsosmallthatinformationcannotpropagatebetweenneighborsinonestepThus,eachelementisisolatedduringonestep,enablingmtkD<SComputationCycleinUDECDECAllthecontactsCONSTITUTIVEAtthecentroidALLTHEBLOCKSMOVEMENTzonenodeAttheelementAtthenodeMOVEMENTALLTHEBLOCKSRIGIDBLOCKSDEFORMABLEBLOCKSGotoTIMESTEPThesolutionschemeusedinDEMisconditionallystableAlimitingtimestepmustsatisfyboththecalculationforinternalblockdeformationandinterblockrelativedisplacementForstabilityoftheblockdeformationcomputation:wheremiisthemassassociatedwithblocknodeiandkiisthemeasureofstiffnessoftheelementssurroundingthenodeForcalculationsoftheinterblockrelativedisplacement,thelimitingtimestepiswhereMministhemassofthesmallestblockinthesystemandKministhemaximumcontactstiffnessThecontrollingtimestepisMECHANICALDAMPINGMechanicaldampingisusedinUDECandDECforstatic(noninertial)solutionsandfordynamicsolutionsForstaticanalysis,theapproachissimilarto“dynamicrelaxation”TheequationsofmotionaredampedtoreachastaticstateasquicklyaspossibleundertheappliedinitialandboundaryconditionsDYNAMICRELAXATIONIndynamicrelaxationblocks(andgridpoints)aremovedaccordingtoNewton’slawofmotionTheequationsofmotionaredampedtoreachaforceequilibriumstateasquicklyaspossibleDampingisvelocityproportional–ie,themagnitudeofthedampingforceisproportionaltothevelocityoftheblocksVelocityproportionaldampingintroducesbodyforcesthatcanaffectthesolutionUDECandDECprovidetwodifferenttypesofdampingtominimizethisproblemforstaticanalysis:adaptiveglobaldamping(DAMPauto)localdamping(DAMPlocal)ADAPTIVEGLOBALDAMPINGAdaptiveglobaldampingisaservomechanismusedtoadjustthedampingconstantautomaticallysuchthatthepowerabsorbedbydampingisproportionaltotherateofchangeofkineticenergyinthesystemAdjustmentoftheviscosityconstantismadebyanumericalservomechanismthatseekstokeeptheratio,R,equaltoagivenratio(eg,)LOCALDAMPINGThedampingforce,Fdis:Dampingforcesareintroducedtotheequationsofmotion:whereFiistheunbalancedforceInUDECandDECtheunbalancedforceratio(ratioofunbalancedforce,Fi,totheappliedforcemagnitude,Fm)ismonitoredtodeterminethestaticstateBydefault,whenFiFm<inUDEC(orinDEC)thenthemodelisconsideredtobeinanequilibriumstateThedampingforceatagridpointisproportionaltothemagnitudeoftheunbalancedforcewiththesignsettoensurethatvibrationalmodesaredampedBASISOFSTATICSOLUTIONSINUDECandDECTheunbalancedforceratio(ratioofunbalancedforce,Fi,totheappliedforcemagnitude,Fm)ismonitoredtodeterminethestaticstateBoththeadaptiveglobaldampingandlocaldampingdynamicsolutionmethodsprovideastaticsolution(withtheeffectofinertialforcesminimized)providedtheunbalancedforceratioreachesasmallvalueThisiscomparabletothe“levelofresidualerror”or“convergencecriterion”definedformatrixsolutionmethodsusedinmanyfiniteelementprogramsInUDECandDEC,theleveloferrorisquantifiedbytheunbalancedforceratioInbothUDECDECandFEsolutions,thestaticsolutionprocessterminateswhentheerrorisbelowadesiredvalueComparisonofadaptiveglobaldampingandlocaldampingAsimpleexample:tenblocksslideonaroughbase*VelocityproportionaltooutofbalanceforcewithproportionalityconstantDynamicrelaxationwithstandardvelocityproportionaldampingAdaptiveglobaldampingLocaldamping*MASS(DENSITY)SCALINGForstaticanalysis,materialinertialmassescanbescaledsothatlocalcriticaltimestepsareincreasedThevalueofinertialmassisirrelevanttomodelingstaticsystems,providedgravityforcesarecorrectlypreserved(Notethatgravitationalmassesarenotaffected)CriticaltimestepcanbeincreasedbecauseitisproportionaltoTheprocedure,called“densityscaling,”scalestheinertialdensityofblocksorzonesbasedontheiraverageblock,orzone,massDensityscalingisinvokedwiththeMSCALEcommandItisturnedonautomaticallywheneverlocaldampingoradaptiveglobaldampingisusedRunningModelsinUDECOverviewofUDECoperation()EngineeringsimulationsusuallyconsistofalengthysequenceofoperationsAUDECdatafilecanbeeasilymodifiedwithatexteditorSeveralfilescanbelinkedtogetherThewordorientedinputfilesprovideanexcellentmeansforkeepingadocumentedrecordofanalysesThecommanddrivenstructureallowsthedevelopmentofpreandpostprocessingprogramstomanipulateUDECinputoroutputasdesiredUDECisacommanddrivenprogramCOMMANDkeywordvalue…<keywordvalue>CommandSyntaxExample,new(clearsthememory)block,,,,(createsablock)crack,,(createsasinglefractureinblock)plotblock(drawstheblockonthescreen)ThereareovercommandsandkeywordsinUDEC!!!OverviewofUDECoperation()UDECisamenudrivenprogramPointandclickoperationaccessesallcommandsandfacilitiesinUDECDesignedtoemulateexpectedWindowsfeaturesDigitizedplotsorgraphicsfilescanbeimportedtoguidemodelgenerationProvidesaccesstoadatabaseofmaterialpro

类似资料

编辑推荐

幼儿园教师教学笔记、幼儿园教师师德师风学习笔记.doc

股市技术分析:欧奈尔选股七大法则.doc

有机热载体炉安装质量证明书&#46;doc.doc

北魏《女尚書王僧男墓志》.doc

拘留所条例.doc

职业精品

精彩专题

上传我的资料

精选资料

热门资料排行换一换

  • 逻辑和集合论.pdf

  • 考夫曼-法律哲学.pdf

  • 最新实验室主任工作手册.pdf

  • 犯罪构成及其关系论-肖中华-人大…

  • 陈瑞华:刑事诉讼的前沿问题.pdf

  • 北京大学刑法学博士文库--刑法判…

  • 壮阳保健药处方.doc

  • 双城记.pdf

  • 林语堂:+圣哲的智慧.pdf

  • 资料评价:

    / 62
    所需积分:1 立即下载

    意见
    反馈

    返回
    顶部