ppt1、接触CONT-L04-Logic

Thefollowingtopicsarecoveredinthislesson.Lessoncontent:ContactLogicandDiagnosticsToolsWorkshop3:BoltedFlangeAnalysis(IA)Workshop3:BoltedFlangeAnalysis(KW),Lesson4:ContactLogicandDiagnosticsTools,2hours,Bothinteractive(IA)andkeywords(KW)versionsoftheworkshopareprovided.Completeonlyone.,ContactLogicandDiagnosticsTools,NewtonMethodTheContactAlgorithmContactDiagnostics:VisualContactDiagnostics:Text,NewtonMethod(1/5),TheNewtonmethodisaniterativemethodusedtosolvenonlinearproblems.,Given:Desiredload“P”Abilitytoevaluatef(u)andK(u)Find:us,suchthatf(us)=P,TheNewtonmethod,however,isnotguaranteedtoconverge.ExampleinwhichNewtoniterationsdiverge:Increasethelikelihoodofconvergencebydecreasingloadincrement.Usemultipleloadincrementstoachievedesiredtotalload.,Diverging!,NewtonMethod(2/5),NewtonMethod(3/5),Abaqusautomaticallyadjuststheloadincrementsize.Goal:Findconvergedsolutionrobustlyandefficientlywithrespecttothenumberofiterations.Basicidea:Trackconvergencerateinordertodeterminewhentoincreaseordecreaseloadincrementsize.Usersuggestsincrementsize;Abaqustriestooptimizeit.,Slowconvergenceordivergence,Convergenceinfewiterations,Increaseincrementsize,Reduceincrementsize,NewtonMethod(4/5),Contactcauseskinksintheloadvs.displacementcurve.Thereisaslopediscontinuityuponchangeincontactstatus.Asaresult,contactchangesinterruptoverallconvergenceratetracking.,ChallengingforNewtonmethod!,1.Bendbeam,2.Contactrigidsurface,3.Compresstip,Status(.sta)fileforthepreviousexample(beamcontact),NewtonMethod(5/5),“Severediscontinuityiterations”(SDIs)AnSDIisaniterationduringwhichcontactconstraintschangestate(open/closed,stick/slip)IdeaistofilteroutcontacteffectsfromconvergenceratetrackingThelogictoadjusttheincrementsizetreatsSDIsseparately,TheContactAlgorithm(1/5),“Hard”contactpressurevs.overclosure:Defaultbehavior:SDIsdonotblockconvergence“ConvertSDI”:smallpenetrations/tensilestressestriggercontactstatuschanges(otherwise,basedonsolutionextrapolation(ifany)Calculatethestiffness,imposingcontactconstraintsaccordingly.Formthesystemofequationsandpassthroughtheequationsolver.Arecontactpressuresandclearancesconsistentwiththeassumedcontactstate?Contactstatuschanges(open/closedorstick/slip)oftencausesignificantchangestothesystemofequationsIterationswithcontactstatuschangesareflaggedasseverediscontinuityiterations(SDIs),3,2,1,TheContactAlgorithm(4/5),Hasconvergencebeenachieved?Bydefault,AbaqusquantifiesthecontactincompatibilitiesassociatedwithSDIs.Theseincompatibilitiesmustbesufficientlysmalltoachieveconvergencewithrespecttothecontactstate.Alsohavetoensurethattheforceresidualsandsolutioncorrectionsaresufficientlysmalltoachieveequilibrium.Ifthecontactstateandequilibriumconditionssatisfytheirrespectiveconvergencecriteria,theincrementiscomplete.Ifconvergenceisnotachieved,isitlikelytobeachieved?Abaqusevaluatestrends,suchasthenumberofcontactstatuschangesinsuccessiveiterations,todeterminewhetherornottocontinueiteratingorcutbacktheincrementsize.Ifconvergenceislikely,updatethecontactconstraintsbasedonandthestiffness,andre-solvethesystemofequations;otherwise,tryagainwithasmallerincrementsize.,5,4,3,TheContactAlgorithm(5/5),ThedefaultlimitontotalSDIsperincrementis50.Inprinciplenotnecessarytolimitthenumberofseverediscontinuityiterations.Sophisticatedcriteriadeterminewhetheriterationshouldbecontinuedorterminated.Inpractice,thedefaultlimitforthemaximumnumberofseverediscontinuityiterationsshouldalwaysbemorethantheactualnumberofiterationsinanincrement.,ContactDiagnostics:Visual(1/8),ContactdiagnosticsexampleusingAbaqus/CAEReference:ExampleProblem1.3.4,Deepdrawingofacylindricalcup,ContactDiagnostics:Visual(2/8),VisualdiagnosticsareavailableintheVisualizationmoduleofAbaqus/CAE.,Step3,Increment6:5iterations(3involveSDIs),ContactDiagnostics:Visual(3/8),ContactDiagnostics:Visual(4/8),Slavenodesthatslip;stick/slipmessagescauseSDIsonlyifLagrangefrictionisusedorifslipreversaloccurs.,ContactDiagnostics:Visual(5/8),ContactDiagnostics:Visual(6/8),ContactDiagnostics:Visual(7/8),ContactDiagnostics:Visual(8/8),ContactDiagnostics:Text(1/4),Contactdiagnosticsexampleusingthemessage(.msg)fileReference:ExampleProblem1.3.4,“Deepdrawingofacylindricalcup”Status(.sta)file:SUMMARYOFJOBINFORMATION:MONITORNODE:200DOF:2STEPINCATTSEVEREEQUILTOTALTOTALSTEPINCOFDOFIFDISCONITERSITERSTIME/TIME/LPFTIME/LPFMONITORRIKSITERSFREQ1111121.001.001.0000.0002110112.001.001.0000.000311100102.010.01000.01000-0.0006003217182.020.02000.01000-0.00120331U9092.020.02000.01500-0.001203325052.020.02380.003750-0.001423413142.030.02940.005625-0.001763512352.040.03780.008438-0.002273613252.050.05050.01266-0.003033714152.070.06950.01898-0.004173816172.100.09790.02848-0.005883913472.140.1410.04271-0.008443101U4042.140.1410.06407-0.0084431027182.160.1570.01602-0.0094031113252.180.1810.02403-0.0108.,ContactDiagnostics:Text(2/4),Messagefile,Step3,Increment6:INCREMENT6STARTS.ATTEMPTNUMBER1,TIMEINCREMENT1.266E-02CONTACTPAIR(ASURF,BSURF)NODE167ISNOWSLIPPING.CONTACTPAIR(ASURF,BSURF)NODE171ISNOWSLIPPING.:CONTACTPAIR(ASURF,BSURF)NODE153OPENS.CONTACTPRESSURE/FORCEIS-830689.CONTACTPAIR(ASURF,BSURF)NODE161OPENS.CONTACTPRESSURE/FORCEIS-1.43706E+006.CONTACTPAIR(ASURF,BSURF)NODE165OPENS.CONTACTPRESSURE/FORCEIS-1.03301E+006.CONTACTPAIR(CSURF,DSURF)NODE363OPENS.CONTACTPRESSURE/FORCEIS-3.43767E+006.CONTACTPAIR(ESURF,FSURF)NODE309ISNOWSLIPPING.5SEVEREDISCONTINUITIESOCCURREDDURINGTHISITERATION.4POINTSCHANGEDFROMCLOSEDTOOPEN1POINTSCHANGEDFROMSTICKINGTOSLIPPING,Slavenodesthatslip;stick/slipmessagescauseSDIsonlyifLagrangefrictionisusedorifslipreversaloccurs.,IncompatibilitiesdetectedintheassumedcontactstateSDI,Duetoslipreversal,*PRINT,CONTACT=YEScausesthisdetailedprintout.(Usefulfortroubleshooting),ContactDiagnostics:Text(3/4),Messagefile,Step3,Increment6(contd):CONVERGENCECHECKSFORSEVEREDISCONTINUITYITERATION1MAX.PENETRATIONERROR-8.1463E-009ATNODE331OFCONTACTPAIR(ESURF,FSURF)MAX.CONTACTFORCEERROR-4184.86ATNODE363OFCONTACTPAIR(CSURF,DSURF)THEESTIMATEDCONTACTFORCEERRORISLARGERTHANTHETIME-AVERAGEDFORCE.AVERAGEFORCE5.350E+03TIMEAVG.FORCE3.137E+03LARGESTRESIDUALFORCE-1.200E+04ATNODE333DOF2LARGESTINCREMENTOFDISP.-7.783E-04ATNODE329DOF2LARGESTCORRECTIONTODISP.-1.684E-05ATNODE337DOF2FORCEEQUILIBRIUMNOTACHIEVEDWITHINTOLERANCE.AVERAGEMOMENT110.TIMEAVG.MOMENT89.0ALLMOMENTRESIDUALSAREZEROLARGESTINCREMENTOFROTATION1.847E-33ATNODE100DOF6LARGESTCORRECTIONTOROTATION6.454E-34ATNODE300DOF6THEMOMENTEQUILIBRIUMEQUATIONSHAVECONVERGED,Convergencechecksforcontactstate,Convergencechecksforequilibrium,Notonlyisthecontactincompatibilitytoolarge,butforceequilibriumhasnotbeenachievedeither,ContactDiagnostics:Text(4/4),Fouradditionaliterationsarerequired;thefirsttwoareSDIs(involvecontactincompatibilities).Inthefinaliterationboththecontactandequilibriumcheckspassandtheincrementconverges.CONVERGENCECHECKSFORSEVEREDISCONTINUITYITERATION2.CONVERGENCECHECKSFORSEVEREDISCONTINUITYITERATION3.CONVERGENCECHECKSFOREQUILIBRIUMITERATION1CONVERGENCECHECKSFOREQUILIBRIUMITERATION2MAX.PENETRATIONERROR-1.24301E-015ATNODE331OFCONTACTPAIR(ESURF,FSURF)MAX.CONTACTFORCEERROR-9.94745E-005ATNODE331OFCONTACTPAIR(ESURF,FSURF)THECONTACTCONSTRAINTSHAVECONVERGED.AVERAGEFORCE5.244E+03TIMEAVG.FORCE3.120E+03LARGESTRESIDUALFORCE-1.98ATNODE135DOF1LARGESTINCREMENTOFDISP.-7.809E-04ATNODE129DOF2LARGESTCORRECTIONTODISP.1.063E-08ATNODE135DOF2THEFORCEEQUILIBRIUMEQUATIONSHAVECONVERGEDAVERAGEMOMENT109.TIMEAVG.MOMENT88.8ALLMOMENTRESIDUALSAREZEROLARGESTINCREMENTOFROTATION1.925E-33ATNODE100DOF6LARGESTCORRECTIONTOROTATION-6