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  • AAiT,MechanicalEngineeringDepartment

  • CourseObjectiveThecourseintroduces:

    y Understandingofprinciplesandpossibilities ofoptimizationinEngineeringandinparticularindesigny Understandhowtoformulateanoptimumdesignproblembyidentifyingcriticalelementsy knowledgeofoptimizationalgorithms,abilitytochooseproperalgorithmforgivenproblemy Practicalexperiencewithoptimizationalgorithmsy Practicalexperienceinapplicationofoptimizationtodesignproblems

  • CourseoutlineChapter1:IntroductiontoEngineeringOptimizationofDesigny Introduction: Historicalbackground,Definitionofterms,Basicconcepts,Classificationofoptimizationsproblems,y Applications:Designoptimization,benefitsofoptimization,automateddesignoptimization,whentouseoptimization,examples

    Chapter2:OptimumDesignFormulationy Designmodels,Mathematicalmodels,Definingoptimizationproblem,Multiobjective

    designproblems,applicationsofoptimizationindesign

    Chapter3ClassicalOptimizationtechniquesy Singlevariableoptimizationy Multivariableoptimizationwithequalityandinequalityconstraints

    Chapter4:Onedimensionalunconstrainedoptimizationtechniquesy Eliminationmethods:Exhaustivesearch,Intervalhalvingmethod,FibonacciMethod,GoldenSectionmethod.

    y Interpolationmethods:quadraticinterpolation,cubicinterpolationy Directrootmethods: Newton'smethod,QuasiNewtonmethod,Secantmethod

  • CourseoutlineChapter5:UnconstrainedOptimizationtechniquesy Directsearchmethods: Randomsearch,GridsearchMethod,Powellmethody Indirectsearch(Descent)methods: Steepestdescent(Cauchy)method,Conjugate

    gradient(FletcherReeves)method,Newtonsmethod,y UnconstrainedoptimizationusingMatlab

    Chapter6:ConstrainedOptimizationtechniquesy Directsearchmethods:Randomsearch,complexsearchMethod,Quadratic

    programmingy Indirectmethods:Penaltyfunctionmethod,Lagrangemultipliermethody ConstrainedoptimizationusingMatlab

    Chapter7:DynamicProgrammingy Introduction,Multistagedecisionprocesses,Applicationsofdynamicprogramming.

    Chapter8:GeneticAlgorithmbasedOptimizationy IntroductiontoGeneticAlgorithm,ApplicationsofGAbasedoptimizationtechniques,GAbasedOptimizationusingMatlab

  • ReferenceMaterials1. S.S.Rao,EngineeringOptimization,3rd edition,WileyEastern,20092. Papalambros andWilde,PrincipleofoptimalDesign,modelingand

    computation,CambridgeUniversitypress,20003. Kalyanmoy Deb,EngineeringDesignforoptimization, PHI,20054. FredvanKeulen andMatthiis Langelaar,LecturenotesinEngineering

    Optimization,TechnicalUniversityofDelft5. Ravindran,Ragsdell andRekalaitis,EngineeringOptimizationMethodsand

    application,2nd edition,Willey,20066. Arora,IntroductiontoOptimumdesign,2nd edition,ElsevierAcademicPress,

    20047. Forst andHoffmann,Optimizationtheoryandpractice,Springer,20108. Haftka andGurdal,ElementsofStructuralOptimization,3rd edition,Kluwer

    academic,19919. Belegundu andChandrupatla,Optimizationconceptsandapplicationsin

    Engineering,2nd edition,CambridgeUniversitypress,201110. Kalyanmoy Deb,MultiobjectiveOptimizationusingEvolutionary

    Algorithms,Wiley,200211. Bendose,Sigmund,Topologyoptimizationtheoryandmethodsand

    applications, Springer,2003

  • PrerequisitesMathematicalandComputerbackgroundneededtounderstandthecourse:y Familiaritywithlinearalgebra(vectorandmatrixoperations)andy basiccalculusisessentialandCalculusoffunctionsofsingleandmultiplevariablesmustalsobeunderstoody FamiliaritywithMatlab andEXCELisalsoessential

  • Lectureoutliney Introductiony Historicalperspectivey Whatcanbeachievedbyoptimization?y Optimizationofthedesignprocessy Basicterminology,notations,anddefinitionsy Engineeringoptimizationy Popularityandpitfallsofoptimizationy Classificationofoptimizationproblemsy Designoptimizationy Benefitsofdesignoptimizationy Automateddesignoptimizationy Examples

  • IntroductionOptimizationisderivedfromtheLatinwordoptimus,thebest.Thusoptimizationfocuseson

    Makingthingsbetter

    Generatingmoreprofit

    Determiningthebest

    Domorewithless

    Thedeterminationofvaluesfordesignvariables whichminimize(maximize)theobjective,whilesatisfyingallconstraints

  • Introductiony Optimizationisdefinedasamathematicalprocessofobtainingthesetofconditionstoproducethemaximumortheminimumvalueofafunction

    y Itisidealtoobtaintheperfectsolutiontoadesignsituation.

    y Usuallyallofusmustalwaysworkwithintheconstraintsofthetime andfundsavailable,wecanonlyhopeforthebestsolutionpossible.

    y Optimizationissimplyatechniquethataidsindecisionmaking butdoesnotreplacesoundjudgmentandtechnicalknowhow

  • Historicalperspectivey AncientGreekphilosophers:geometricaloptimizationproblems

    y Zenodorus,200B.C.:Asphereenclosesthegreatestvolumeforagivensurfacearea

    y Newton,Leibniz,Bernoulli,DelHospital (1697):Brachistochrone Problem:

  • Historicalperspectivey Peoplehavebeenoptimizingforever,buttherootsformoderndayoptimizationcanbetracedtotheSecondWorldWar.y AncientGreekphilosophers:geometricaloptimizationproblems

    y Zenodorus,200B.C.:Asphereenclosesthegreatestvolumeforagivensurfacearea

    y Newton,Leibniz,Bernoulli,DelHospital (1697):Brachistochrone Problem:y Lagrange(1750):constrainedminimizationy Cauchy(1847):steepestdescenty Dantzig (1947):Simplexmethod(LP)y Kuhn,Tucker(1951):optimalityconditionsy Karmakar (1984):interiorpointmethod(LP)y Bendsoe,Kikuchi(1988):topologyoptimization

  • Historicalperspectivey Oneofthefirstproblemsposedinthecalculusofvariations.y Galileoconsideredtheproblemin1638,buthisanswerwasy incorrect.y JohannBernoulliposedtheproblemin1696toagroupofy elitemathematicians:y I,JohannBernoulli...hopetogainthegratitudeofthewholescientificcommunitybyplacingbeforethefinestmathematiciansofourtimeaproblemwhichwilltesttheirmethodsandthestrengthoftheirintellect.Ifsomeonecommunicatestomethesolutionoftheproposedproblem,Ishallpubliclydeclarehimworthyofpraise.

    y Newtonsolvedtheproblemtheverynextday,butproclaimedIdonotlovetobedunned[pestered]andteasedbyforeignersaboutmathematicalthings."

  • Whatcanbeachievedbyoptimization?

    y Optimizationtechniquescanbeusedfor:y Gettingadesign/systemtoworky Reachingtheoptimalperformancey Makingadesign/systemreliableandrobust

    y Alsoprovideinsightiny Designproblemy Underlyingphysicsy Modelweaknesses

  • Whatcanbeachievedbyoptimization?Engineeringdesignistocreateartifactstoperformdesiredfunctionsundergivenconstraintsy Commongoalsforengineeringdesigny Functionalityy Betterperformance:Moreefficientoreffectivewaystoexecutetasksy Multiplefunctions:Capabilitiestoexecutetwoormoretaskssimultaneously

    y Valuey Higherperceivedvalue:Morefeatureswithlesspricey Lowertotalcost:Sameorbetterownershipandsustainabilitywithlowercost

  • BasicTerminology,notationsanddefinitionsRn ndimensionalEuclidean(real)spacex columnvectorofvariables,apointinRn

    x=[x1,x2,..,xn]T

    f(x),f objectivefunctionx* localoptimizerf(x*) optimumfunctionvaluegj(x),gj jth equalityconstraintfunctiong(x) vectorofinequalityconstrainthj(x),hj jth equalityconstraintfunctionh(h(x) vectorofequalityconstraintfunctionC1 setofcontinuousdifferentiablefunctionsC2 setofcontinuousandtwicedifferentiabledifferentiable

    continuousfunctions

  • Norm/Lengthofavectory Ifweletxandybetwondimensionalvectors,thentheirdot

    productisdefinedas

    y Thus,thedotproductisasumoftheproductofcorrespondingelementsofthevectorsxandy.

    y Twovectorsaresaidtobeorthogonal(normal)iftheirdotproductiszero,i.e.,xandy areorthogonalifxy=0.

    y Ifthevectorsarenotorthogonal,theanglebetweenthemcanbecalculatedfromthedefinitionofthedotproduct:

    y where istheanglebetweenvectorsxandy,and||x||representsthelengthofthevectorx.Thisisalsocalledthenormofthevector

  • Norm/Lengthofavectory Thelengthofavectorxisdefinedasthesquarerootofthe

    sumofsquaresofthecomponents,i.e.,

    y ThedoublesumofEq.(1.11)canbewritteninthematrixformasfollows

    y SinceAxrepresentsavector,thetripleproductoftheaboveEq.willbealsowrittenasadotproduct:

  • BasicTerminologyandnotationsDesignvariables

    y Parameterswhosenumericalvaluesaretobedeterminedtoachievetheoptimumdesign.

    y Theyincludesuchvaluessuchas;sizeorweight,orthenumberofteethinagear,coilsinaspring,ortubesinaheatexchanger,oretc.

    y Designparametersrepresentanynumberofvariablesthemayberequiredtoquantifyorcompletelydescribeanengineeringsystem.

    y Thenumberofvariablesdependsuponthetypeofdesigninvolved.Asthisnumberincreases,sodoesthecomplexityofthesolutiontothedesignproblems.

  • BasicTerminologyandnotationsConstraintsy Numericalvaluesofidentifiedconditionsthatmustbesatisfiedtoachieveafeasiblesolutiontoagivenproblem.y Externalconstraintsy Uncontrolledrestrictionsorspecificationsimposedonasystembyanoutsideagency.

    y Ex.:Lawsandregulationssetbygovernmentalagencies,allowablematerialsforhouseconstruction

    y Internalconstraintsy Restrictionsimposedbythedesignerwithakeenunderstandingofthephysicalsystem.

    y Ex.:Fundamentallawsofconservationofmass,momentum,andenergy

  • Whatismathematical/EngineeringOptimization?Mathematicaloptimizationistheprocessof1. Theformulationand2. Thesolutionofaconstrainedoptimizationproblemofthe

    generalmathematicalformMinimize f(x),x=[x1,x2,,xn]T subjecttoconstraints

    gj(x) 0,j=1,2,,mhj(x)=0,j=1,2,.,r

    Wheref(x),gj(x)andhj(x)arescalarfunctionsoftherealcolumnvectory Thecontinuouscomponentsofxiofx=[x1,x2,,xn]T arecalled

    the(design)variablesy f(x) istheobjectivefunction,y gj(x) denotestherespectiveinequalityconstraints,andy hj(x)theequalityconstraintfunction

  • Whatismathematical/EngineeringOptimization?y Theoptimumvectorxthatsolvestheformerlydefinedproblemisdenotedbyx*withthecorrespondingoptimumfunctionvaluef(x*).

    y Ifnoconstraintsarespecified,theproblemiscalledanunconstrainedminimizationproblem

    y OthernamesofMathematicalOptimizationy Mathematicalprogrammingy Numericaloptimization

  • ObjectiveandConstraintfunctionsy Thevaluesofthefunctionsf(x),gj(x),hj(x)atanypointx=[x1,x2,,xn]T gj(x),mayinpractise beobtainedindifferentways

    i. Fromanalyticallyknownformulae,e.g.,f(x)=x12+2x22+Sinx3

    ii. Astheoutcomeofsomecomplicatedcomputationalprocesse.g.,g1(x)=a(x)amax,wherea(x)isthestress,computedbymeansofafiniteelementanalysis,atsomepointinstructure,thedesignofwhichisspecifiedbyx;or

    iii. Frommeasurementtakenofaphysicalprocess,e.g.,h1(x)=T(x)To,whereT(x)isthetemperaturemeasuredatsomespecifiedpointinareactor,andxisthevectorofoperationalsettings.

    PresenterPresentation NotesThe first two ways of function evaluation are by far the most common. The optimization principle that apply in these cased, where computed function values are used, may be carried over directly to also be applicable to the case where the function values are obtained through physical measurement.

  • ElementsofoptimizationDesignspacey ThetotalregionordomaindefinedbythedesignvariablesintheobjectivefunctionsUsuallylimitedbyconstraintsy Theuseofconstraintsisespeciallyimportantinrestrictingtheregionwhereoptimalvaluesofthedesignvariablescanbesearched.y Unboundeddesignspacey Notlimitedbyconstraintsy Noacceptablesolutions

  • Optimizationinthedesignprocess

    Conventionaldesignprocess:

    Collectdatatodescribethesystem

    Estimateinitialdesign

    Analyzethesystem

    Checkperformancecriteria

    Isdesignsatisfactory?

    Changedesignbasedonexperience/heuristics/

    wildguesses

    Done

    Optimizationbaseddesignprocess:

    Collectdatatodescribethesystem

    Estimateinitialdesign

    Analyzethesystem

    Checktheconstraints

    Doesthedesignsatisfyconvergencecriteria?

    Changethedesignusinganoptimizationmethod

    Done

    Identify:1. Designvariables2. Objectivefunction3. Constraints

    PresenterPresentation NotesTaken from J.S. Arora Introduction to Optimum Design, fig. 1-2.

  • Optimizationinthedesignprocessy Isthereoneaircraftwhichisthefastest,mostefficient,quietest,mostinexpensive?

    Youcanonlymakeonethingbestatatime.

  • OptimizationMethods

  • ComparisonofConventionalandOptimalDesigny TheCDprocessinvolvestheuse

    ofinformationgatheredfromoneormoretrialdesignstogetherwiththedesignersexperienceanintuition

    y Itsadvantageisthatthedesignersexperienceandintuitioncanbeusedinmakingconceptualchangesinthesystemortomakeadditionalspecificationsintheprocedure

    y TheCDprocesscanleadtouneconomicaldesignsandcaninvolvealotofcalendartime.

    y TheODprocessforcesthedesignertoidentifyexplicitlyasetofdesignvariables,anobjectivefunctiontobeoptimized,andtheconstraintfunctionsforthesystem.

    y Thisrigorousformulationofthedesignproblemhelpsthedesignergainabetterunderstandingoftheproblem.

    y Propermathematicalformulationofthedesignproblemisakeytogoodsolutions.

  • OptimizationpopularityIncreasinglypopular:y Increasingavailabilityofnumericalmodelingtechniques

    y Increasingavailabilityofcheapcomputerpowery Increasedcompetition,globalmarketsy Betterandmorepowerfuloptimizationtechniquesy Increasinglyexpensiveproductionprocesses(trialanderrorapproachtooexpensive)

    y Moreengineershavingoptimizationknowledge

  • Optimizationpitfalls!y Properproblemformulationcritical!y ChoosingtherightalgorithmforagivenproblemyManyalgorithmscontainlotsofcontrolparametersy Optimizationtendstoexploitweaknessesinmodelsy Optimizationcanresultinverysensitivedesignsy Someproblemsaresimplytoohard/large/expensive

    PresenterPresentation NotesIt is generally accepted that the proper definition and formulation of a problem takes roughly 50 percent of the total effort needed to solve it. Therefore, it is critical to follow well defined procedures for formulating design optimization problems.

    The importance of properly formulating a design optimization problem must be stressedbecause the optimum solution will only be as good as the formulation.

    For example, if we forget to include a critical constraint in the formulation, the optimum solution will most likelyviolate it because optimization methods tend to exploit deficiencies in design models. Also,if we have too many constraints or if they are inconsistent, there may not be a solution to thedesign problem.

  • Structuraloptimizationy Structuraloptimization=optimizationtechniquesappliedtostructuresy Differentcategories:y Sizingoptimizationy Materialoptimizationy Shapeoptimizationy Topologyoptimization

    t

    E, R

    r

    L

    h

  • StructuraloptimizationInegrated optimaldesignofavehicleroadarm.y a)InitialFiniteElement

    Model,y b)topologyoptimizedroadarm,y c)reconstructedsolidmodel,y d)FiniteElementmeshforshapedesigny e)VonMises stressoftheshapeoptimizeddesignandy f)comparisonofthe3DRoadarm beforeandaftershapedesign

  • Sizingoptimizationy Inatypicalsizingproblemthegoalmaybetofindtheoptimalthicknessdistributionofalinearlyelasticplateortheoptimalmemberareasinatrussstructure.

    y Theoptimalthicknessdistributionminimizes(ormaximizes)aphysicalquantitysuchasthemeancompliance(externalwork),peakstress,deflection,etc.whileequilibriumandotherconstraintsonthestateanddesignvariablesaresatisfied.

    y Thedesignvariableisthethicknessoftheplateandthestatevariablemaybeitsdeflection.

  • Shapeoptimizationy Shapeoptimization ispartofthefieldofoptimalcontroltheory.

    y Thetypicalproblemistofindtheshapewhichisoptimalinthatitminimizesacertaincostfunctionalwhilesatisfyinggivenconstraints.

    y Inmanycases,thefunctionalbeingsolveddependsonthesolutionofagivenpartialdifferentialequationdefinedonthevariabledomain.

  • Shapeoptimization

    YamahaR1

  • Topologyoptimizationy Topologyoptimizationis,inaddition,concernedwiththenumberofconnectedcomponents/boundariesbelongingtothedomain.Suchusdeterminationoffeaturessuchasthenumberand locationandshapeofholesand theconnectivityofthedomain.

    y Suchmethodsareneededsincetypicallyshapeoptimizationmethodsworkinasubsetofallowableshapeswhichhavefixedtopologicalproperties,suchashavingafixednumberofholesinthem.

    y Topologicaloptimizationtechniquescanthenhelpworkaroundthelimitationsofpureshapeoptimization.

  • TopologyoptimizationTopologyoptimizationisamathematicalapproachthatoptimizesmateriallayoutwithinagivendesignspace,foragivensetofloadsandboundaryconditionssuchthattheresultinglayoutmeetsaprescribedsetofperformancetargets.

    y Usingtopologyoptimization,engineerscanfindthebestconceptdesignthatmeetsthedesignrequirements

  • Topologyoptimizationexamples

  • WhyDesignOptimization?

    DesignComplexity

  • Classificationsy Problems:y Constrainedvs.unconstrainedy Singlelevelvs.multilevely Singleobjectivevs.multiobjectivey Deterministicvs.stochastic

    y Responses:y Linearvs.nonlineary Convexvs.nonconvexy Smoothvs.nonsmooth

    y Variables:y Continuousvs.discrete(integer,ordered,nonordered)

  • TypicalDesignProcess

    InitialDesignConcept

    SpecificDesignCandidate

    BuildAnalysisModel(s)

    ExecutetheAnalyses

    DesignRequirementsMet?

    FinalDesign

    Yes

    No

    ModifyDesign

    (Intuition)

    Time

    Money

    IntellectualCapital

    HEEDS

    $

    HEEDS(HierarchicalEvolutionaryEngineeringDesignSystem)

  • AGeneralOptimizationSolution

    Automotive CivilInfrastructure

    BiomedicalAerospace

  • AutomatedDesignOptimization

    CreateParameterizedBaselineModel

    CreateHEEDSDesignModel

    ExecuteHEEDSOptimization

    PlanDesignStudy

    BasicProcedure:

  • AutomatedDesignOptimization

    Identify: Objective(s)ConstraintsDesign VariablesAnalysis Methods

    Note: These definitions affect subsequent steps

    CreateParameterizedBaselineModel

    CreateHEEDSDesignModel

    ExecuteHEEDSOptimization

    PlanDesignStudy

  • AutomatedDesignOptimization

    InputFile(s)

    ExecuteSolver(s)

    OutputFile(s)

    ValidateModel

    CreateCAD/CAEModelsforaRepresentative Design

    CreateParameterizedBaselineModel

    CreateHEEDSDesignModel

    ExecuteHEEDSOptimization

    PlanDesignStudy

  • AutomatedDesignOptimization

    DefineInputFilesandOutputFiles

    DefineDesignVariablesandResponses

    DefineObjectives,Constraints,andSearch

    Method

    TagVariablesinInputFilesand

    ResponsesinOutputFiles

    DefineBatchExecutionCommandsforSolvers

    CreateParameterizedBaselineModel

    CreateHEEDSDesignModel

    ExecuteHEEDSOptimization

    PlanDesignStudy

  • AutomatedDesignOptimization

    CreateParameterizedBaselineModel

    CreateHEEDSDesignModel

    ExecuteHEEDSOptimization

    PlanDesignStudy ModifyVariablesinInputFile

    ExecuteSolverinBatchMode

    ExtractResultsfromOutputFile

    Optimized Design(s)

    Yes

    NewDesign(HEEDS)

    NoConverged?

  • CAEPortals

    When

    What

    Where

  • TangibleBenefits*Crashrails: 100%increaseinenergyabsorbed

    20%reductioninmass

    Compositewing: 80%increaseinbucklingload15%increaseinstiffness

    Bumper: 20%reductioninmasswithequivalentperformance

    Coronarystent: 50%reductioninstrain

    *Percentagesrelativetobestdesignsfoundbyexperiencedengineers

  • ReturnonInvestment

    ReducedDesignCosts Time,labor,prototypes,tooling Reinvestsavingsinfutureinnovationprojects

    ReducedWarrantyCosts Higherqualitydesigns Greatercustomersatisfaction

    IncreasedCompetitiveAdvantage Innovativedesigns Fastertomarket Savingsonmaterial,manufacturing,mass,etc.

  • Suggestsmaterialplacementorlayoutbasedonloadpathefficiency

    Maximizesstiffness Conceptualdesigntool UsesAbaqus StandardFEAsolver

    Topology Optimization

  • WhentoUseTopologyOptimization

    y Early in the design cycle to find shape conceptsy To suggest regions for mass reduction Topology

    optimization

  • DesignofExperiments

    Determinehowvariablesaffecttheresponseofaparticulardesign

    Designsensitivities Buildmodelsrelatingtheresponsetothevariables

    Surrogatemodels,responsesurfacemodels

    B

    A

  • WhentoUseDesignofExperiments

    Following optimization

    Toidentifyparametersthatcausegreatestvariation inyourdesign

  • ParameterOptimizationMinimize(ormaximize): F(x1,x2,,xn)

    suchthat: Gi(x1,x2,,xn)

  • ParameterOptimizationObjective:Searchtheperformancedesignlandscapetofindthehighestpeakorlowestvalleywithinthefeasiblerange

    Typicallydontknowthenatureofsurfacebeforesearchbegins

    Searchalgorithmchoicedependsontypeofdesignlandscape

    Localsearchesmayyieldonlyincrementalimprovement

    Numberofparametersmaybelarge

  • SelectinganOptimizationMethod

    DesignSpacedependson:

    Number,typeandrangeofvariablesandresponses

    Objectivesandconstraints

    GradientBased Simplex Simulated

    Annealing

    ResponseSurface GeneticAlgorithm Evolutionary

    Strategy

    Etc.

  • DesignOptimizationProcedureUsingANSYSy Theoptimizationmodule(OPT)isanintegralpartoftheANSYS

    programthatcanbeemployedtodeterminetheoptimumdesign.

    y Whileworkingtowardsanoptimumdesign,theANSYSoptimizationroutinesemploythreetypesofvariablesthatcharacterizethedesignprocess:

    y designvariables,y statevariables,andy theobjectivefunction.

    y ThesevariablesarerepresentedbyscalarparametersinANSYSParametricDesignLanguage(APDL). TheuseofAPDLisanessentialstepintheoptimizationprocess.

    y Theindependentvariablesinanoptimizationanalysisarethedesignvariables.

  • DesignOptimizationProcedureUsingANSYSOrganizeANSYSprocedureintotwofiles:y Optimizationfiledescribesoptimizationvariables,andtriggertheoptimizationruns.y Analysisfileconstructs,analyses,andpostprocessesthemodel.y TypicalCommandsinanOptimizationFile

    01020304050607080910111213

    /CLEAR ! Clear model database... ! Initialize design variables/INPUT, ... ! Execute analysis file once

    /OPT ! Enter optimization phaseOPCLEAR ! Clear optimization databaseOPVAR, ... ! Declare design variablesOPVAR, ... ! Declare state variablesOPVAR, ... ! Declare objective functionOPTYPE, ... ! Select optimization methodOPANL, ... ! Specify analysis file nameOPEXE ! Execute optimization runOPLIST, ... ! Summarize the results... ! Further examining results

  • DesignOptimizationProcedureUsingANSYS

    010203040506070809101112

    /PREP7... ! Build the model using the

    ! parameterized design variablesFINISH

    /SOLUTION... ! Apply loads and solveFINISH

    /POST1 ! or /POST26*GET, ... ! Retrieve values for state variables*GET, ... ! Retrieve value for objective

    function... FINISH

    TypicalCommandsinanAnalysisFile

  • DesignOptimizationProcedureUsingANSYSANSYSOptimizationAlgorithmsTwobuiltinalgorithmsinANSYS:y Firstordermethody Subproblemapproximationmethod(Zeroordermethod)

    OtherOptimizationToolsProvidedbyANSYSy SingleIterationDesignTooly RandomDesignTooly GradientTooly SweepTooly FactorialTool

  • Summary

    y Designvariables:variableswithwhichthedesignproblemisparameterized:y Objective:quantitythatistobeminimized(maximized)Usuallydenotedby:(costfunction)y Constraint:conditionthathastobesatisfiedy Inequalityconstraint:y Equalityconstraint:

    ( ) 0g x( ) 0h =x

    ( )f x

    ( )1 2, , , nx x x=x K

  • Summaryy Generalformofoptimizationproblem:

    ( )xxxxxhxg

    xx

    =

    nX

    f

    0)(0)(

    )(

    :to subject

    min

  • Summaryy Optimizationproblemsaretypicallysolvedusinganiterativealgorithm:

    Model

    Optimizer

    Designvariables

    Constants Responses

    Derivativesofresponses(designsensitivities)

    hgf ,,

    iii xh

    xg

    xf

    ,,

    x

    Engineering Optimization Course Objective Course outlineCourse outlineReference MaterialsPrerequisites Lecture outline IntroductionIntroductionHistorical perspectiveHistorical perspectiveHistorical perspectiveWhat can be achieved by optimization ?What can be achieved by optimization ?Basic Terminology, notations and definitionsNorm/Length of a vectorNorm/Length of a vectorBasic Terminology and notations Basic Terminology and notations What is mathematical/Engineering Optimization ? What is mathematical/Engineering Optimization ? Objective and Constraint functions Elements of optimizationOptimization in the design processOptimization in the design processOptimization MethodsComparison of Conventional and Optimal DesignOptimization popularityOptimization pitfalls!Structural optimizationStructural optimizationSizing optimizationShape optimization Shape optimization Topology optimizationTopology optimizationTopology optimization examplesWhy Design Optimization ?Classifications Typical Design ProcessA General Optimization SolutionAutomated Design OptimizationAutomated Design OptimizationAutomated Design OptimizationAutomated Design OptimizationAutomated Design OptimizationCAE PortalsTangible Benefits*Return on InvestmentSlide Number 50When to Use Topology OptimizationDesign of ExperimentsWhen to Use Design of ExperimentsParameter OptimizationParameter OptimizationSelecting an Optimization MethodDesign Optimization Procedure Using ANSYSDesign Optimization Procedure Using ANSYSDesign Optimization Procedure Using ANSYSDesign Optimization Procedure Using ANSYS Summary Summary Summary