User Subroutine in ABAQUS(1)

UserSubroutineinABAQUS1.HowcanIgetinformationofeachnodeinUMATIampresentlyworkingonABAQUS(Standard)User-Subroutines.IknewAbaquscaninputUMATsomeinfoofcurrentintegrationalpoint,buthowcanIgettheinformationofeachnodeinUMAT?especiallytheuandcoordinate ofeachnodeincurrentincrementstepwhenumatiscalled.A1:usingoutputvariableCOORD(User'sManual:4.1.2,Section)youcanhaverequiredinformation.Syntaxisasfollowing*NODEPRINT,NSET=corner_nodeU,RF**ELPRINT,ELSET=elementCOORD,SIfyouareusingCAEthenfollowthisway_goto, STEPmodule->output->fieldoutputrequest manager->volume/thickness/coordinate->COORD,Currentnodal co-ordinateThencheckthe*.datfiletoseetherequestedinformation.in'volume/thickness/coordinate'youwillaslofindsomeotherinterestinginformations.A2:AllyoucandoiscallURDFILandgetthenodalvaluesfromthelastincrement.Ifthatisn'tgoodenoughthenyouneedtogotoaUEL.2.UELoutputQ:IhaveaUELsubroutinewhichbydefaultsendsoutputtothelogfilecreatedbyabaqus(jobname.log).I'dlikeittosendtheformattedoutputtoafileofmychoiceinstead.Itriedthefollowingbutitdoesn'tseemtowork.Cluesanyone?open(1,FILE='test.dat')write(1,*)JELEM,kappa,kincA:Youprobablyneedtospecifyafullpathname.Yourcodecreatesafileinthescratchdirectorywhichgetsdeletedwhenthejobfinishes.Alsoyouneedtoavoidusingreservedunitnumbers.Unit#'sover100aresafe,checkthemanualforotherrules.Q:ThankyouGeorge.Sillyofmenottohavethoughtofthat!Itworksfinenowwiththefullpath.3.MultipleusersubroutinesIhavebeenusinga*creepsubroutineforafewmonths.Iamnowtryingtoadda*usdfldsubroutine,howeverIcan'tseemtogetabaqustorecognisebothsubroutines.ItwillonlyreadthelastoneIwriteonthecommandline?Doesanyoneknowhowtoattachtwosourcefiles?Theabaqusmanualsaysthatitispossible,butnothowtodoit.A1:Ifyouareusingafortransubroutine,justpastethecodeofthesecondsubroutineafterthefirstsubroutine.Thusinthesamef-file.A2:I'mtryingtouseaUSDFLDsubroutineinconjunctionwithaCREEPsubroutine,andIfollowedtheinstructionbelowfromKarelin:"Ifyouareusingafortransubroutine,justpastethecodeofthesecondsubroutineafterthefirstsubroutine.Thusinthesamef-file."NowIhaveaproblemwiththeGETVRMsubroutinethatshouldbecalledbyUSDFLD.ABAQUSabortswhenItrytorunitwithUSDFLDcontainingthecallofGETVRM(itdoesnotifthecallisnotpresent).WhatamIdoingwrong?A3:Youneedtosupplymoredetailsforustoanswerthis.ObviouslyyouarecallingGETVRMtoobtainparametersattheelementsornodes.HaveyoucheckedtheGETVRMargumentlist(s)tomakesureit(they)is(are)correct.IsuggestyouputsomeprintstatementsinyourUSDFLDcodebeforeandafterthecallstoGETVRM,andelsewhere,tofindoutwheretheabortoccurs.Youmayfindthatyouaretryingtouseanun-setvariableinUSDFD,forexample.Q:Ialreadysolvedtheproblemthankstoaninspirationfromheaven.NowIhaveanotherquestion:inmycreepmodelIhaveaparameter(whichisnotstrain,stress,temperature,mechanicalpropertiesorsimilar)thatchangeswithequivalentstrain.Thelawrelatingthisparametertotheequivalentstrainisexperimental,thusisgivenastwoparallelcolumnsofdatainadatafile.WhichisthesimplestwaytoinputthesedataintheABAQUSmodel?IsitpossibletomaketheUSDFLDfilereadtherelevantdatafile(Ithinkthiswouldbecumbersomebecauseitshouldbedoneateachintegrationpoint)?A4:Ifthedatafileisnotexcessivelylarge,whynotincludeitasa2DarrayinUSDFIL?Ateachint.stationloopthroughthearraytofindtheparametervaluecorrespondingtotheequiv.strain.Otherwiseyoucouldopenthefiletoreaditateachint.station.NotethatyoumustuseafortranunitnumbernotreservedbyABAQUS.4.Abaqus–UMATIamusingaUMATtoimplementamathematicalmodeldescribingthecharacteristicsofcertainbiologicalmaterials.TheproblemisthatwiththisUMAT,Iwishtodescribeatthecurrentintegrationpointbeinganalysed,acharacteristicofthismaterialrelativetoisolatedreferencepositions(integrationpoints).IunderstandaUserSubroutineisonlyinterestedwithcalculationsfortheintegrationpointatwhichithasbeencalled.ThearrayCOORDS,inmyunderstanding,ispassedinonlyforthepositionoftheintegrationpointunderanalysisandisnotconcernedwithanyotherpointswithinmodelasawhole.IwaswonderingifthereisanywayofinputtingintotheUMATthepositionofotherintegrationpoints.Thesereferencepositionswillchangeateachincrementsoneedtobeconstantlyupdated.A:There'snodirectapproachforthis.ButyoucanuseanARRAYinaCOMMONblocktostorethecoordinatesoftheintegrationpoints.TheinformationinCOMMONblockcanbemadeavailablewithinanysubroutineincludingUMAT.You'llonlyneedausersubroutinecalledatthebeginningofanalysis(e.g.SDVINI)tofillupthisarray.Butbeawarethatifyou'reusingNLGEOM=ONinstepdefinition,thentheCOORDSofintegrationpointswillvarywithtime.5.DISPSubroutineIamexperimentingwiththeDISPsubroutinetoassignauser-defineddisplacementboundaryconditionina3Dstatic-stressanalysis.Myproblemissomewhatsimple:Iwouldliketouseatriangulardistributionforthedisplacementboundarycondition.Thatis,thedisplacementboundaryconditionwillbelinearlydependentononeofthecoordinates.Letssay:U2=12-2(COORD1)  U2beingtheassigneddisplacementsinthe"2"directionandCOORD1isthenodalcoordinatesinthe"1"direction.Iwaswonderingifanyofyouhadanexperiencewiththissubroutineandcouldgivemesomepointers?OrifyouhappentohaveatechnicalnoteorasampleinputfileandcouldpassitmywayIwouldtrulyappreciate.A1:Can'tyoudownloadtheDISP-subroutines"udispxxx.f"and"udispxxx_part1.f"andcorrespondinginputfilesfromABAQUSverificationmanual.(Section4.1.2)Inaddition,youcandownloadlotofwrittenandtestedprogramsandsubroutinesfrom:A2:So,whatkindofproblemareyourunninginto? Whatyoudescribesoundsstraightforward. TheonlycomplicationcouldbethattheCOORDarraycontainsthecurrentcoordinates. So,unlessyouwantyourboundaryconditionstocontinuallychange,you'llhavetostorethecoordinatespassedinwhenKSTEP=KINC=1inastaticarray(dimensionedtostorethecoordinatesofallofthenodesbeingprocessedbyDISP)sothatyouhaveaccesstotheoriginalcoordinates.6.SubroutineUMAT(ROTandDFGRD1)IampresentlyworkingonABAQUS(Standard)User-Subroutines.IamusingUMATforaspecialmaterialmodel.IambasicallyinterestedinobtainingtheROTATIONMATRICES(ROT)andDEFORMATIONGRADIENTS(DFGR1)forasingleknownelementwhosenumberisknown. IhavebeentryingtoprintthisdataintheDATfile,butbeenunsuccessful.Cansomeonepleasegiveanideaofwhatlogic(orsyntax)canIuseinmyusersubroutinewhichisafortrancode.A:IfIunderstandyourquestioncorrectly,thenwhatyouwantshouldbesomethinglike:IF(NOEL.EQ.myElementNumber)THENWRITE(6,*)"DFGRD1:"WRITE(6,10)DFGRD1(1,1),DFGRD1(1,2),DFGRD(1,3)WRITE(6,10)DFGRD1(2,1),DFGRD1(2,2),DFGRD(2,3)WRITE(6,10)DFGRD1(3,1),DFGRD1(3,2),DFGRD(3,3)ENDIF10 FORMAT(3(2X,E12.5))7.HowtopasselementstrainintousersubroutineDFLUX?Q:Iamdoingananalysisinwhichtheheatgenerationisdependentontheamountofshearstraininthestructure. Iamusingthecoupledtemp-displacementelementsandwritingusersubroutineDFLUXtodefinebodyheatfluxbasedontheamountofstraininanelement. Thestraininthestructureisconstantanddoesnotvaryduringtheanalysis(atleastfornow). Thequestionis,howcanIpassthestrainatanintegrationpointintousersubroutineDFLUX? IsupposeIcouldperformaseparateanalysistogenerateafilefortheamountofstrainateachintegrationpointthatDFLUXcouldreadin,butIamlookingforamoreelegantwaytoaccomplishthisinoneanalysis.A:I'dtryusingadummyuser-definedfielddefinedthroughthesubroutineUSDFLD. WithinUSDFLDyoucanthenusecallstoGETVRMtoretrievethestrainvaluesandstorethenecessarydatainanarraythatissharedwithDFLUXthroughanamedCOMMONblock.Q:Thanks,Dave. Ihavedoneitexactlythatwayinthepast. Iwashopingtherewasamoredirectway.8.usersubroutine:singlevs.doubleprecisionQ1:Hasanyonehadthedifficultyofrunningausermaterialwhere,ifdoubleprecisionisspecifiedonthecommandline,thenthesimulationaborts("limitreachedfortraptypeINVALID"withanabnormalterminationsignal6),butthatwhensingleprecisionisspecified,thesimulationcompleteswithoutruntimeerror?Whatmaypossiblybecausingthis?Q2:Forawhile,IwasstrugglingwithastrongsensivityofmyVUMATtodouble-precisioncalculations,andmyworkaroundswerestrange--Iwaswonderingifsomeoneinthegrouphadencounteredanythingsimilar.IhadbeenrunningonABAQUS6.4.1. Theerror,"limitreachedfortraptypeINVALID,"mademethinkofoverflow/underflow,andinfact,oneofthecausesofthetraperrorwasmyuseoftheSQRTfunctiontogetstresscomponents,whichIthenrephrasedusingdotproductsandIgotfarther. Anothercauseofthetraperrorwasmyuseofthe'dimension'statementtointroducenewarrayswithintheVUMAT.Changingthearraydeclarationsusingthe'real'statementfixedthatproblem. Butthestrangestthingofallwasmyuseofthe'xplb_abqerr'utilitytoprintcalculatedquantitiestothestatusfile. Withsingle-precisiontheprintedresultsofoneofmystatevariablesmatchedtheresultsfromtheplotsintheoutputdatabase.ButwhenIuseddouble-precision,thexplb_abqerrprintoutsarearound10e60timesthecorrectvaluesthatshowupontheoutput-databaseplots.Hasanyonecomeacrossthesetypesofanomalies? ThanksA1:Incaseyouweren'tawarethestandard'includeaba_param'statementgivesyouanimplicitsingleordoubleprecisionstatementatcompiletime.Myguessisyouareseeingtype-mismatcherrorsresultingfromsomevariablesbeingexplicitlydeclaredsingle/doubleandsomeothersrelyingontheimplicitstatement.Q:Thanksforyourinformation;you'vegottenmeinterestedinthe'includeaba_param'statement,andIplantolookitupinthemanuals.IwashopingthatbyexplicitlydeclaringallofmyvariablesintheVUMAT,thenIwouldbesafe. Theresultshadbeenmixed. Atsomeearlierpoint,Ifoundthatdeclaring'doubleprecision'forallofthevariablesandarraysstalledthesimulation,afterwhichIwentto'real'. It'skindofmysterious.A1:Ifyouwanttobeabletoswitchbetweensingle/doublethenallofyourarguments,andalsoanyvariablesthatgetpassedtoabaqusutilitysubroutines*mustbe*implicitlydeclared. Variablesthatarestrictlylocalcanbeexplicitlydeclaredandgenerallyyouwillbeokbecausefortranshouldtakecareofthetypeconversionwhereneeded.Primarilyyouneedtowatchforpassingwrongtypesassubroutinearguments.Q:Ijustthoughtbacktosomeearliertests,andIrememberedthatifIdidn'tdeclaremyarraysintheVUMATexplicitly,thentheytookonzerovalues,always. IfIdeclaredthemusingthe'dimension'statement,thenIgottraperrors. Sothe'real'and'doubleprecision'statementsweremyonlyworkingoptionsfordeclaringarrays.Hasthisbeenyourexperience?A2:Whatdoyoumeanbytraperrors?Ideclaremyarrayswithdimalways...Q:Hereisoneofmyearlierpostingsdescribinganexperiencewith"trap"errorsinQ2Thetraperroralsocomeswithan"abnormalterminationsignal6." Idon'tthinkIhavehonedinontheexactcauseoftheerrors/strangeprintouts,soIdospendmoretimedebuggingandcheckingnumbers.9.QuestionontheusageofsubroutineUSDFLDtoshiftmat1tomat2!MycaseisIwanttoshiftthematerialstatefrom1to2inanheattransferanalysisandwhenagivetemperaturepointhasbeenachievedinanintegratepoint,thematerialproperties(density,conductivity,etc.)ofthisintegratepointwillchangetomaterial2fromitsoriginalmaterial1state,andfromthenonthepointwillbeofmaterial2state,IwanttouseUSDFLDsubroutinetorealize,andiampuzzledthathowtowritethematerialdependenceinthe.inpfile,cananyonehelpme?Apartofmymaterial1&2areasfollowed(densityistemperaturedependent):material1state:density:8490.11,208464.08,1008427.58,2008389.22,3008349.17,4008307.64,5008264.8,600material2state:density:8010,207980,1007931,2007890,300                    7842,4007801,5007755.0,600so,Mywanttomakeanfieldflag(0or1)astheswitchtorealize:*material,name=****density,DEPENDENCIES=18490.11,20,08010,20,18464.08,100,07980,100,18427.58,200,07931,200,18389.22,300,07890,300,18349.17,400,07842,400,18307.64,500,07801,500,18264.8,600,07755.0,600,1.......................Fordensity,atfirst,alltheintegratepointismaterial2,whenthetemperatureofaintegratepointincreasedto600,itwillbechangedtomaterial2,say,7755at600.Fromthenon,ifthetemperatureoftheintegratepointdecreased,thispointwillstillbeofmaterial2.Iamnotsurewhethermyinputfileisrightornot?A:Whynotsimplymakethematerialpropertiesfunctionsoftemperature,whichtheyobviouslyare? You'llprobablyhavetodefineafiniterangeoftemperaturesoverwhichthetransitionoccurs,butotherthanthatIdon'tseeanyrealproblem.10.WritingoutputtocurrentdirectoryusingFORTRANUELIneedtooutputsomevariablestoafileinthecurrentworkingdirectory.Insteadofspecifyingthecurrentdirectoryexplicitly,Itriedusing"open(1000,DEFAULTFILE=FILE$CURDRIVE,FILE='test.txt')",wheretest.txtisthefileIwanttooutputinformationinto.aftergivinga"USEDFLIB"statementatthebeginningofthesubroutine.IdothissoIwon’tneedtochangetheUELcodeeverytimeIworkinanewdirectory.Butthisdoesn'tseemtowork.Itsays"FILE$CURDRIVE"doesnothaveatype,eventhoughthetypeandthefunctionofthevariablearedeclaredinDFLIB.Wonderwhat'swrongwithit.cluesanyone?A1:Yes,andthereisareasonforthat:ABAQUStakesyourinputfiles,createsatemporarydirectory,andrunseverythinginthatdirectory,soanyfilesyoucreateinyoursubroutinewillbedeletedafterasuccessfulrun,UNLESSyoueither:a)hardcodethepathinyoursubroutineb)usetheGETOUTDIRsubroutineprovidedbyABAQUS(see26.1: UtilityRoutinesinthemanual,thereareacoupleofjewelsthere)Notethatifyouonlyneedtooutputthosevariables,butnotprocessthemfurtherwithanotherprogram,itmightbeeasiertooutputtotheDATorMSGfiles(seetheintroductiontotheUserSubroutineschapter).Hopethishelps.A2:TheselinesworkperfectlyunderWindowsandLinuxwithasubroutineFILM.Thefullpathhastobespecified.open(unit=200,file='C:\Calculs\SMA\Calcul_THE_f/POST_FLUX.post',1status='UNKNOWN',position='APPEND')100 format(a30,i10,i3,1pe14.3,1pe14.3)write(200,100)SNAME,NOEL,NPT,TEMP,H(1)*(TEMP-SINK)close(200)ItshouldworkwithyourUEL!Q:ThanksalotFernando(A1),Theutilitysubroutine"GETOUTDIR"cameinreallyhandy.Benz(A2),Iwasabletoimplementwhatyouaresuggesting.ButIdon'twanttochangethedirectorypathinthecodeeverytimeItransferthecodetoanewdirectory,hencemyquestion."GETOUTDIR"doesthejobinthiscase.11.uel_externalforceIamcodingauelsubroutineof8nodes3dlinearelasticelement,butimetadifficulttounderstandtoexternalforcetransmitaionfromtheabaqustothesubroutine.Therearetwokeyproblems:(1)HowistheconcentratedforcepassedintotheUEL;(2)HowisthedistributedforcepassedintotheUELinabaqusdocumentation,therearefewmaterialaboutthisoptionandistillcannotgetthroughit.A1:Concerningdistributedloadswhicharethemoredifficult:asyouknowadistributedloadisappliedviathe*DLOADcommandinside*STEP.Forexample*DLOAD,1,U2,5.0associatesaloadofmagnitude5.0withloadkeyU2onelement1(oryoucanspecifyanelementcomponent).Inthiswayyoucanpickoutallthesurfaceelementsonwhichyouwillapplythesurfaceload.AsfarasIknowitisnotpossibletospecifyuser-definedloadsdirectlyonsurfaces(althoughtheelementloadU2canbeinterpretedasasurfaceload,seenextpara).NBTheloadkeyUnisnotthesameastheelementkeyUn.ItisuptoyoutointerprettheloadkeyU2.Forexample,itmightbeasurfaceloadonface3appliedtodof2.Ifthereismorethanonefaceinvolved,ormorethanonedofthensimplyrepeatthe*DLOADcommandwithdifferentUn.Notethatbothfaceindexandcomponentindexareimpliedintheloadkey.Insidetheuelsubroutineyoucanexaminetheelementloadsthroughthearraysjdltyp(k,1)andadlmag(k,1).IntheusualcaseAbaquswillaugmenttheloadautomaticallyegifthereare5substepsthentheloadswillcomeinas1,2,3,4,5.Nowyoumustinterprettheloadanddecidewhattodowithit.Inthecaseofadistributedloadyouwillmostlikelywanttointegrateoverthesurfaceegint_SfnN_adSwherefnisthegivenload,N_aistheshapefunction.Theintegrationiscarriedoutinasimilarmannertotheusualtractionvolumeintegrals.Youwillwanttodefinegaussintegrationpointsandweightsfortheelementface.Aftertheintegrationthetheresultingnodalloadvectorissimplyaddedtotherhsvector.It'sabitmessy,butworthspendingtimeoversothatyougetitright.It'smucheasiersecondtimearound:)Tryandbuildtheshapefunctioncomputationsintoalibrarymodule.Asalwaysexperimentwithasingleelementandcheckresultsbyhand.A2:1)ConcentratedloadsareNOTpassedontotheUEL,theyareassembleddirectlyintotheglobalforcevector.2)Usethistrick:ifthedistributedloadisasurfaceload,createmembraneelementswithnegligiblestiffnessandapplytheloadtothatsurface,thatwayyouspareyourselfassemblingelementalloads(i.e.letABAQUSdoit).Forvolumetricloads,takegravityasanexample:youneedthematerialdensity,whichisgivenasamaterialproperty(therefore,youdefinewhichpositionoftheUEL_PROPERTYyouuseforthat),andthegravityacceleration,whichistheactualvolumetricload.Thetotalforceiscalculatedatelementlevelbycomputingtheelementvolume.Idon'tremembertheinterfaceforUELexactly,butIseemtorememberthedistributedloadcoefficientsarepassedwiththesubroutine,andavalueinLFLAGSissetifyouneedtooutputtheelementvector.ChecktheUELdocumentationfortheexactdetailsonhowtheloadispassed(inthegravitycase,theaccelerationandmaybethecoordinatesystemitisgiven).12.modellingorthotropicviscoelasticmaterialQ:IamanewAbaqususer.IamtryingtomodelaviscoelasticorthotropicmaterialbutitseemsthatAbaqus/explicitonlyallowstheviscoelasitcmaterialoptiontobeusedwithisotropicmaterials.Ifthisiscorrect,itmeansthatavumatsubroutineshouldbeusedtomodelorthotropicviscoelasticbehaviour.Hasanyoneeverwrittensuchasubroutine?Couldanyonegivemeguidanceonhowtowriteone?A:yes,youareright.YouneedaVUMATforthat,itispossible,acomradeofminehasdoneitseveralyearsago.Imayrecommendanadditivedecompositionofthestresstensorintotwoparts:elasticandviscosity.Willyouhavesmallstrainsandlargerotations?Q:Thanksforyourreply.IwillhavelargestrainsasI’mmodellingthecompressionofsofttissue(muscle)upto30%strain.A:Mhhh,hardworktodo!Trytofindpapersonnon-linearviscoelasticity.WhatyouhavetoknowisthatyouhavetoreturntheCauchystresstensorintheGreen-NaghdibasisattheendoftheVUMAT.13.umat/vumatnblock(Materialpoints)Subroutineterminologydefinesnblockasnumberofmaterialpoints.Whatarematerialpoints.Ihaveahugemeshofaround1000elements.Andmysubroutinetellsmethatvalueofnblockis136.Whatdoesitindicate?A1:> WhatarematerialpointsThey'realsocalledintegrationpoints. Ifthatdoesn'tsoundfamiliarthenyoushouldn'tbeattemptingtowriteaVUMAT.> Ihaveahugemeshofaround1000elements.That'sanextremelysmallmeshbytoday'sstandards.> Andmysubroutinetellsmethatvalueofnblockis136. Whatdoesitindicate?That'sthenumberofmaterial(integration)pointsbeingpassedinduringthatcalltoVUMAT. VUMATprocessesanarrayofmaterialpointsinonecall. Additionalcallsaremadeuntilallmaterialpointshavebeenprocessed.A2:Yes,theVUMATpassafixednumberofGausspointsateachcall,maybebecauseofsome"vectorizedsparse"solvertechnology.Inotherwords,youcannotknowatwhichintegrationpointyoucomputesomething.14.STATEVARIABLE!!Iamworkingonsoilmechanicsproblem,Iamcompressingthedrysoilwithsomeinitialrelativedensity(voidratio).Inmycase,voidratioisvaryingwithrespecttodisplacement(orincreasevericalpressure).Iwantdefineasafunctionofpressure.Whichsubroutineistoused..CanIusesolutiondependentstatevariable?A1:Ithinkyoucanuseumatsubroutinesinceyouwanttodefineyourownconstitutiveequation.A2:Haveyoulookedcarefullyattheavailablesoilmechanicsmodelstoseeifonewilldowhatyouwant?Idon'tknowifthereisone,butthatiswhereyoushouldstart.Developingaumatisasignificantundertakingthatyoudon'twanttogetintoifnotnecessary.15.OUTPUT!!Q:iamdoingpowdercompactionsimulation.iwouldliketo getmyresultsintermsofRelativedensity.Inabaqusiamgettingresultsintermsofvoidratio.thereisarelationbetweenvoidratioandrelativedensity.eachtimeaftermysimulation,iammanuallyconvertingthevoidratiointorelativedensityinabaqus(createoutputfieldsfromoutputcommand)byusingtherelation,relativedensity=1/(1voidratio).ifanyoneknowswhichsubroutinetouse,pleasesuggestme..2)duringcompaction,young'smodulusofthematerialis varyingstartingfromcompactiontoendofcompaction.shouldiuseusersubroutineoristhereanyotherwayicangivethechangeofyoung'smoduluswithrespecttocompaction..A:a) Ican'tthinkofasubroutineatthemomentbutIthinkyoucanwriteashortroutineusingtheabaqusstatevariables(statev).D0=initialdensityD=densityE11=STATEV(1)E22=STATEV(2)E33=STATEV(3)E12=STATEV(4)D =STATEV(5)STATEV(5)=D0*DEXP(-1.0*(STATEV(1)STATEV(2)STATEV(3)))Youcanrelatevoidfractionwithdensitybasedontheconstitutivemodelyouareusing.Onceyoudothatyoucanthenprinttheoutputtoyour.datfile.thesignintheequationabovechangeswhetheryouaredoingcompactionortensionanalysesb)Thechangeintheyoung'smodulusdependsontheconstitutivemodelyouareusing.Youcan'treallydescribethechangearbitraryasthisdependsonthematerialyouarelookingitandthecompactiontestyouareusing.Ihopeitmakessense.Letmeknowhowyougeton.Q:thanksforreplying..iwilltrytoimplementitbyusingstatevariable.iwillletyouknowwhathappened.ifpossiblepleasefindhowtogivevaryingyoung'smoduluswithchangeindensity.16.ContactConvergenceissueWehaveaprobleminvolvingcontactsbetweenSpringandMagnetandarefacingconvergenceissues.Itwouldreallyhelpfulif