(完整word版)abaqusXFEM方法介紹

裂紋擴展分析體驗熱分析中的熱物性參數(shù)：材料密度，熱導率，比熱容，電阻率，彈性模量，融化潛熱的焓、泊松比、散熱系數(shù)。在ABAQUS模型中，需用3D的deformable、shell、exctrusion方式建立一個初始裂紋，長短適宜，初始裂紋要從開始起裂的點設置。由于計算方法目前還不穩(wěn)定，參數(shù)要適當調(diào)整。設置網(wǎng)格劃分參數(shù)的時候，應該對稱設置，否則網(wǎng)格不對稱。斷裂應力的大小要和斷裂能量的設置相應，能量太大、太小導致不易收斂，斷裂區(qū)域的網(wǎng)格要規(guī)則，各個方向尺寸要差不多，整個厚度方向單元數(shù)量一致，且越少越好，即使裂紋起始點兩側(cè)單元未參與裂紋，也要盡可能均勻規(guī)則，裂紋擴展的區(qū)域不能被PARTION開，應該是一體的。沖擊動載荷時，載荷步時間應盡可能小，maxpsdamage應力應大于ductiledamage應力。初始裂紋不能在單元界限擴展，否則導致不收斂。裂紋可在兩種彈性金屬界面上。適用于彈性材料、兩種彈性材料界面裂紋和冪硬化材料。我建立的彈塑性材料模型不容易收斂，把塑性去掉后反而容易收斂。建立ductilemanage模型時，需要材料的塑性行為，但必須同時有tractionmanage模型，否則就提示某些單元的fracturedamage模型未能建立？。tractionmanage模型和ductilemanage模型中的damageevolution中的類型和數(shù)值要相同。初始屈服應力和斷裂應力不能差太多。動力學的沖擊裂紋分析，不能有塑性（當然也不能有ductiledamage），可能是因為incrementtime太大了？（或者是先分析一下不帶塑性材料的，通過了才分析有塑性材料的？）斷裂能量要和斷裂應力相適應，否則可能因為能量太高，還未達到，但應力達到了，導致裂紋不開裂、計算不收斂。能量太低，很容易就滿足了能量開裂原則，但應力未達到，裂紋不能開裂、計算不收斂。能量的高低也影響到穩(wěn)定擴展裂紋的長短：能量低的時候，由于需要很少的能量即可實現(xiàn)裂紋擴展，因此穩(wěn)定擴展的裂紋在不長的時候即會失穩(wěn)擴展；能量太高的時候，在裂紋穩(wěn)定擴展的過程中試樣積累了相當?shù)哪芰?，因此穩(wěn)定擴張一段時間后，試樣內(nèi)部的能量和外加能量就可以實現(xiàn)裂紋的失穩(wěn)擴展，穩(wěn)定擴展段也不會很長。平面應力比平面應變問題更容易收斂。加寬垂直于裂紋走向的單元長度尺寸有利于收斂。？以下是別人的資料。在abaqus中創(chuàng)建裂紋1.createpart如圖1所示：匚reatePartName:Part-1ModelingSpace3DC2DPlanarAxisymmetricT/peOptionseDeFormableDiscreterigidNoneavailableAnalyticalrigid?EulerianBaseFeatureQShellWirePointApproximatesize:20匚ontinue...|匚呂「1匚創(chuàng)]圖12.進入草圖模式，創(chuàng)建一矩形板3*6，點鼠標中鍵2次退出草圖模式，如圖2所示

圖2匚reatePartName:P^rt-2ModelingSpace3DQ2DPlanarAxisymmetricTypeOptionsDeformableDiscreterigidNoneavailableAnalyticalrig泊Eul&rianBaseFeatureShellq嗣咤PointApproximatesize:20Continue...Cancel模型來給出裂紋初始位置。4.定義材質(zhì)Name:Material-1Description:MaterialBehaviorsElasticGeneralMechanicalThermalOther

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PlasticityDamageforDuctileMetalsElasticTyp已:IsoUseterDamageForTractionSeparationLawsk￡uadeDamageDamageforFiber-ReinforcedComposites?MaxeDamageDamageforElastomers>QuadsDamageDeformationPlasticityMaxsDamageDampingNaxpeDamageEjgoansionMaxpsDamacieBrittleCrackingSubopNumberofModulitimeNoconrNoten：Young'sModulusPoisson'sRatio121OE90.3DataDataMaxPrincipal

Stress844E6:工...辿口口蟲口念DamageEvalution最后定義圖為5.定義截面屬性CreateSectionName:Section-1■EditSectionName:Section-lType:^olidjHomogeneous賦值part-1，part-2就不用賦值了啊裝配OKApplyCancelStep■CreateStepxTJName:Step-11InsertnewstepafterInitialProceduretype:GeneralDynamijExplicitDynami匚!Temp-dispjExplicitGeostaticHeattransferMassdiffusionSoilsStatiCjGeneralStatiCjRiksContinue...CancelEditStepName:5tep-lType:StatiCjGeneralBasicIncr&mentatianotherT沖e;tAutomaticFixedNasirmumnumberafincrements:100000InitialMinimumMaximumIncrementsize:0.01lE-00^0.05Interaction■CreateInteractionProp...Name:JntProp-1TypeContactFilmconditionCavityradidtionAcousticimpedan匚亡IncidentwaveActuator/sensorContinue...Cancel直接創(chuàng)建crackxfem不需要在創(chuàng)建seam了Inertiak?Crack?AssignSeam...csDelete5earn...SpecialF&atureToolsPlug-insHelp比Springs/DashpotskFastenerskManager...匚reate...匚reate匚rackName:Crack-1TyPeContourintegral^FEM“"匚oritinum,,,匚arcsIName;Crack-1Nene￡■Specify:■Name;Crack-1Nene￡■Specify:■[select...QK■EditCrack■iQllowcrackgrowth匚racklocation:feeciFz.contactproper^dintProp-1Type:XFEMRegion:(Picked)■[Edit,,,](XV2)++丿人衛(wèi)二Region選擇整個面Cracklocationspecifyselect選擇part-2否則就是自動判斷了啊并指定接觸屬性Whenanelementiscutbyacrack,thecompressivebehaviorofthecracksurfaceshastobeconsidered.Theformulaethatgovernbehaviorareverysimilartothoseusedforsurface-basedsmall-slidingpenaltycontactHowever,thefrictionalbehaviorisnotyetconsideredinthesheardirection.

在重新進入stepEditFieldOutputRequest:設置Failure/Fracture中的凹越磁瀕匹也HState/Field/UserjTimeSDVjSolutiondependentstatevariablesF7jPredefinedfieldvariablesMFRjPredeFinedmassflowratesLiyARM?User-deHnedoutputvariablesSTATUSjStatus(samefailureandplasticitymodels;VUMM)V5TA叫耳童工％..昊或豎.云￡.世.叩..element；忘了就看不見裂紋擴展只能看見應力場

Load■EditBoundaryConditionName!BC-1T/pe:5tep;Region:Displacement/Rotation5tep-l(StaticGeneral)(Picked)匚(Global')[Edit…|[匚飛目花…]丿U2:UR3;Distribution:Create...radiansAmplitude:Create...丿U2:UR3;Distribution:Create...radiansAmplitude:Create...Mote:Thedisplacementvaluewillbemaintainedinsubsequent"呂psOKCancelOK■EditBoundaryConditionName:BC-2Type;Step:Displacennent/R.otatiQnStep-1(StatiqGenerslORegion:(Picked)Name:BC-2Type;Step:Displacennent/R.otatiQnStep-1(StatiqGenerslORegion:(Picked)C5Y5:(Global)Edit...匚reate,,,UR.3:Distribution:Create...Amplitude;UR.3:Distribution:Create...Amplitude;OKOKNote:Thedisplacementvaluewillbemaintainedinsubsequentsteps.Cancel□□□Sweep?Multiple［艮呂忖對inwEwqicinQarn呂匡…OK□□□Sweep?Multiple［艮呂忖對inwEwqicinQarn呂匡…OKDefaults匚ancelMesh同樣只需對part-1進行網(wǎng)格劃分MeshControlsEle：mentShapeRbijsd=Quad-dcirriin.dtedTriTechniqueAlgorithmOptions?■'阿nimizethemeshtransitionTip,,,FreecStructured單元選擇為cpe4最后的網(wǎng)格如圖所示最后一步：修改keywordsModelViewportViewSeedMeehManager...Create...匚卯yModelCofiyObjects.."EditAttributesK-v-Module:MeTIsdEditKeywordsKModel-1c口.En-amekDelete左M.Al-priAkf1}k田?+.田{門:!」「口￡」1’?‘11i1，1^DamageInitiation,criterion=MAXP58.446+07,改為^DamageInitiatiorijcriterion=MAXP58.446+07,^DamageStabiliz