RBARTutorial

RBARTutorial

RBARTutorial

RBARDefined

RBARisanelementtypespecifictotheSierraSDphysicscodeandasaresultthistutorialisonlyapplicablewhenusingSierra/SD(Salinas).Itisessentiallya“rigid”barelementthathasnoextension,torsion,orbending.Itisoftenaconvenientwaytotransferorapplyloads.

RBARTutorial

CreateaNewModel• ChooseFile->New->Modelinthemenu• ChooseNewModel thenNext• ChooseCreateFromTemplatethenNext• EnterRBAR astheModelName• ChoosetheSierraSDTemplates->StructuralDynamics->TopologyOptimization templateandthenFinish

RBARTutorial

CreatetheDesignDomain

• AttheCUBIT commandpromptcopyandpastethefollowingcommands(seeHintonnextslide):brickx10cylinderradius2height10sub2from1cylinderradius2.5height10webcut volume1toolvolume3deletevol 3imprintallmergeall

RBARTutorial

Hint:CubitConsole• Ifyoudon’tseetheCUBIT> promptintheconsolewindowyouarejustlookingatthewrongconsole(theremaybemultipletochoosefromloadedinPlatothatusethesingleconsolewindow).Clickontheiconatthetoprightoftheconsolewindowthatlookslikeacomputerscreentotogglethroughthedifferentconsolesthatarecurrentlyloaded.Oryoucanclickonthedownarrownexttothecomputerscreenicontoseeallofthecurrentlyloadedconsolesandchooseonefromthelist.

RBARTutorial

CreatetheMeshandRBARs• AttheCUBIT commandpromptcopyandpastethefollowingcommands(seeHintonnextslide):createvertex000vol allsize.5meshvol allmeshvert19block1jointvert19spidersurf10block2vol 4block3vol 1

• ClickontheGeometry/MeshnodeinthetreeandthenclicktheSave iconinthetoolbartosavethemodel

• The“block…joint”commandcreatestheblockwithRBARelementsconnectingthepoint0,0,0andeverynodeontheinteriorofthecylindricalsurface.

• Wewillapplyourloadingtothesinglevertexat0,0,0andtheRBARelementswilltransferthatloadtotheinteriorofthecylindricalsurface.

RBARTutorial

ApplyaForceLoad

• Selectandright-clickthevertex(seeHintonnextslide)inthemiddleofthecylindricalsurfaceandchooseApplyLoads->nodeset (thevertexistheonethatalloftheRBARelementsareconnectedto).• IntheSettings panelselectforce fromthedrop-downlistandenter00-1e5 intheboxtotherightandhitthereturnkey.

RBARTutorial

Hint:EntitySelection• Theselectionfiltertoolbarisatthebottomleftofthegraphicswindow.• Thereare3highlevelmodes:Geometry,Mesh,andExodus• Withineachhighlevelmodetherearevariousoptionsforfilteringwhatwillgetselectedbyclicksinthegraphicswindow.

Highlevelmodes

Filteroptionsforagivenhighlevelmode

RBARTutorial

CreateaFixedBC• Createanodeset fromthe8verticesatthe8cornersofthecubebytyping“nodeset 2vertex1to8” attheCUBIT prompt.• ChoosetheNodeset selectionfilteratthebottomofthegraphicswindow.• Selectnodeset 2byselectingandright-clickingonanyofthe8cornersofthecubeandchooseApplyBoundaryConditions->boundary• IntheSettings panelselectnodeset 2 andthencheckthefixedcheckbox.

RBARTutorial

AssignMaterialandElementType• ClickontheFEMMesh nodeinthetreeunderSierraStructuralDynamics->FiniteElementModel

• IntheSettings panelclickintheMaterial areanexttoBlocks2and3andselect1 fromthedropdownlist.Don’tsetamaterialforBlock1sinceitwillbetheRBARblock.IfthematerialforBlock1isalreadysetto1thenjustclickonitandselecttheblankentryfromthedropdownlist.

• ThenclickintheElement areanexttoBlock1andselectrbar fromthedropdownlist.

• ThenclickintheElement areanexttoBlocks2and3andselecthex8u fromthedropdownlist.

RBARTutorial

SettheTop.Opt.Parameters• ClickontheTopologyOptimization->TOPOLOGY-OPTIMIZATION nodeinthetree

• IntheSettingspanelright-clickanywhereintheParameters areaandchooseAdd->fixed_block_ids.Enter“12” (1and2separatedbyaspace)forthevalueofthefixed_block_ids parameterandhitthereturnkey.ThistellsPlatototreatblocks1and2asfixedandasaresulttheywillberespectedaspartofthefinalresult.Block1,theRBARblock,mustbesetasfixedsotheoptimizerdoesnottrytoperformoptimizationontheRBARelements.Astheyarenotvolumeelementsremovingoraddingmaterialdoesnotmakesense.

• IntheParametersareasetthefollowingparametervaluesbyclickingonthemandthenenteringthevalueintheeditfield:• volume_fraction =0.3• filter_scale =2.0• max_num_optimization_itr =30

RBARTutorial

RuntheOptimization• ClickontheSierraStructuralDynamics nodeinthetreetobringupthejobsubmissionpanelintheSettings view• ChooseSalinas asthecodeandthenchoosethemachineandexecutiontemplateyouwanttouse• IntheResources areamakesureRBAR.exo ischecked.Thisisthemeshfilethatwillbeusedintherun.• IntheCodeParameters areamakesureAutoPrune isuncheckedandNumberofRefines is0.Wewillnotbeusingpruningandrefininginthisexample.• ChooseanyotherpreferencesandlaunchthejobbyclickingonSubmitSimulationJob towardthetopofthepanel

RBARTutorial

ResultsTheresultsshouldlooksomethinglikethatshownbelow.