Numerical Analysis of Thermal Stress and Deformation.pdf

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1、NumericalAnalysisofThermalStressandDeformationinMulti-LayerLaserMetalDepositionProcessesHengLiu,ToddE.Sparks,FrankW.LiouDepartmentofMechanicalandAerospaceEngineeringDavidM.DietrichDepartmentofEngineeringManagementandSystemsEngineeringMissouriUniversityofScienceandTec

2、hnology1870MinerCircle,Rolla,MO65409AbstractDirectmetaldeposition(DMD)hasgainedincreasingattentionintheareaofrapidmanu-facturingandrepairing.Thisprocessinvolvesextremelyhighthermalgradientsandheatandcoolingrate,resultinginresidualstressesanddistortion.Thispaperpresen

3、tsa3Dsequentiallycoupledthermo-mechanicalfiniteelementmodeltopredictresidualstressesanddeformations.Thetemperaturedistribution,thermalstressfieldandgeometrydeformationacrossdomainareillustrated.Theeffectofdepositionparametersonresidualstressanddeflectionsarealsoex-plore

4、d.Asetofvalidationexperimentsformechanicaleffectswereconductedusinglaserdisplacementsensor.Thecomparisonsbetweenthesimulatedandexperimentalresultsshowgoodagreement.1IntroductionHighlylocalizedheatingandcoolingduringDMDprocessproducesnonuniformthermalex-pansionandcont

5、raction,resultingincomplicateddistributionofresidualstressintheheataffectzoneandunexpecteddistortioninthewholestructures.Theresidualstressmaypromotefractureandfatigueandinduceunpredictablebucklingduringtheserviceofdepositedpartswhilethedis-tortionisoftendetrimentalto

6、thedimensionalaccuraciesofstructures.Therefore,itisvitaltopredictthematerialbehaviorafterDMDprocessandoptimizethedesign/manufacturingparame-terstocontroltheresidualstressanddistortion.ThetemperaturefieldandresidualstressduringDMDprocesshavebeenpreviouslyinvesti-gatedb

7、ymanyscholars.KimandPeng[1]useda2DFiniteElementmodeltosimulatethetem-peraturefieldinlasercladdingprocess.Longetal.[2]developeda3Dmultiple-trackFEMmodeltosimulatethetemperaturehistoryoflaserdirectmetalshapingprocess.Intheircases,onlysim-plethermalprocesssimulationsarep

8、resentwhilenoresidualstressanalysisareconducted.Someresearchershavetriedtoobtainthedistributionofresidualstressfromexperiments.Fore