(ebook) - Nastran Tutor

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1、6-1CHAPTER6AnalyzingaModelObjectivesInthisexerciseyouwilllearnto•Settheinitialcondition.•Usesimulationcontrols.•Measurereactionforces.•Displayvectors.•Specifythetranslucencyofabody.•Fine-tuneasimulationandverifytheresult.SoftwareMSC.visualNastran4DorMSC.visualNast

2、ranMotionSupportFiles•TutorialsChapter06Piston.wm36-2Chapter6—AnalyzingaModelTheMSC.visualNastranDesktopmodelsthatyouanalyzecanbecreatedby1)exportingamodelfromyourfavoriteCADsoftwareasdiscussedinChapter5,“ExploringCADIntegrationandAssociativity”,2)buildingamodel

3、fromscratchinMSC.visualNastranDesktop,asdiscussedinChapter7,“BuildingaModel”,or3)openingaCADfilewithinMSC.visualNastranDesktop.OpentheModelFile1.LaunchMSC.visualNastranDesktop.2.ChooseOpenfromtheFilemenu.3.BrowsetolocateTutorialsChapter06Piston.wm3andclickOpen.T

4、hemodelofthepistonassemblyisdisplayedinthedocumentwindow,asshowninthefigurebelow.Figure6-1ModelofaPistonAssembly4.ClicktheRunbuttonintheTapePlayerControl.Thisbasemodelshowsthepistonmechanisminmotion,drivenbythemotorattachedtothecrankshaft.Sincethisisthefirsttimeth

5、esimulationisrun,MSC.visualNastranDesktopcalculatesthedynamicsandstoresthedata.5.RepeatthesimulationbyclickingtheStopbutton,thentheResetbutton,andthentheRunbuttonagain.Theanimationmaybefasterthistimebecausethehistoryhasalreadybeencalculated.SettheInitialCondition6

6、-3SettheInitialConditionMSC.visualNastranDesktopallowsyoutomanipulateandconfigurepartswithoutbreakingtheassemblyconstraintsthatwerecreatedwhenthemodelwasbuiltinMSC.visualNastranDesktoporintheCADsystem.Inthisstep,youwillmovethepistonassembly’sconfigurationsothatthe

7、simulationstartshalfwaythroughthecombustionorcompressioncycle.1.ClicktheMovetoolintheEdittoolbar.2.Movethemouseoverthesidesurfaceofthecrankshaftcounterweight.Asyoumovethemouseoverobjectsinthemodelingwindow,adashedboxappearsaroundthemtoshowthattheyareframed.Figure6

8、-2BoundingBoxShowingFramedObject3.Holdthemousebuttondown,anddragthemousetorotatethecrankshaft.Asyoudragthemouse,thecrankrotatesaroundthecrankpin.4.Posit