Engineering Design and Applications (MAEG3920)

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EngineeringDesignandApplications

Prof.LiZhang

DepartmentofMechanicalandAutomationEngineering

TheChineseUniversityofHongKong

Engineering Design and Applications (MAEG3920)

Chapter 5

Generating and Evaluating Design Alternatives

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Learningobjectives

Learnhowtogeneratedesignalternatives Learnhowtoevaluatedesignalternatives

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Review

Whatwehavelearnt? Thedesignprocess(Chapter2)

Definingthedesignproblem(Chapter3)

Attributelist Objectivelist Objectivetree Metricsofobjectives Constrainsofobjectives

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Review

Whatwehavelearnt? Definingthefunctionsandrequirementsofthedesign(Chapter4)

Functionexpression(transformationofenergy,materialsandinformation)

Functionanalysis(inputandoutputrelationship) Blackbox Openbox

Specifyingfunctions Functionvalues Interface

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Generatedesignalternatives

Whatwewilllearninthischapter?

Generativedesignalternatives

Evaluatedesignalternatives

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Generatedesignalternatives Wecangeneratedesignalternativesusing

morphologicchart Creatingamorphchart

Foreachdesignfunction,wecangeneratealistofdesignalternatives

Anexample:Beveragecontainer Objective:promotesales

Containbeverage Materialforbeveragecontainer Provideaccesstojuice Displayproductinformation Sequencemanufactureofjuiceandcontainer

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Generatedesignalternatives Anexample:beveragecontainer(continue)

Designoptions

Function Alternatives

Containbeverage Can,Bottle,Bag,Box

Material forbeveragecontainer Aluminum,Plastic,Glass,Waxedcardboard,Linedcardboard, Mylarfilms

Provide accesstojuice Pulltab, Insertedstraw,Twisttop,TearCorner,Unfoldcontainer,Zipper

Displayproductinformation Shapeofcontainer,Label,Color

Manufacturing Sequenceofjuiceandcontainer

Concurrent,Series

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Generatedesignalternatives Anexample:Beveragecontainer(continue)

Morphologicchart(Possiblealternatives:4x6x6x3x2=864)

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Morphologicchart:feasible andinfeasiblesolutions

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Morphologicchart:feasibleandinfeasible solutions

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Generatedesignalternatives

Notesingeneratingamorphologictree Thefunctionsshallbeatthesamelevel(forthebeveragecontainer,wewouldnotincludemeansofresistingtemperatureandmeansforresistingforcesandshockswithinthemorphchartinthelastslide,becausetheyaremoredetailedfunctionsthatderivefromsubgoals thataremuchfurtherdownintheobjectivetree.) Themorphchartcanalsobeusedtoexpandthedesignspaceforlarge,complexsystemsbylistingprincipalsubsystemsinastartingcolumnandthenidentifyingvariousmeansofimplementingeachofthesubsystems.

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Anotherexampleofmorphologictree:singleboardcomputerdesign

Onesubsystemcouldbecooling,thatneedsfurtherdetaileddesign

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Generatedesignalternatives Largedesignspacesarecomplexbecauseofthecombinatorial

possibilitiesthatemergewhenhundredsorthousandofdesignvariablesmustbeassigned.

Moreover,oneaspectofdesigncomplexityisthatcollaborationwithmanyspecialistsisoftencritical teamspirit.

Decomposingcomplexdesignspaces Basicidea:divideandconquer Ineachsubsystem

Thenumberofpotentialdesignsislimited Thenumberofdesignvariablesissmall Thedesignvariablescantakeonlylimitedrange

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Generatedesignalternatives Limitingthedesignspacetoausefulsize

Availabletechnologies(majorinfluence:theuserneeds) Availablematerials Thechoiceofmaterialsaffectappearanceofaproduct,itsmanufacture,anditsprice.

Otherexternalconstraints(e.g.theavailabilityofmanufacturingcapabilities).

Toavoidthelistofissuesandofcandidatedesignsbecometoolarge(ortoosilly),wecould:(i)invokeandapplyconstraints.(ii)freezethenumberofattributesbeingconsideredtoavoiddetailsthatareunlikelyseriouslytoaffectthedesignatthispoint(e.g.thecolorofabike)

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Expandandprunedesignspace

Designgenerationisacreativeactivitytowardsagoal Takingadvantagesofdesigninformationthatisalready

available Informationsources

Google ThomsonReuters,

Approaches Benchmarking Reverseengineering(What/how/whydoesthisdo? theprocessissimple:webeginwithameansthathasbeenusedbyapreviousdesigner,thendeterminewhatfunctionsarerealizedbythatgivenmeans.Wethenexplorealternativewaysofdoingthesamething.

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Expandandprunedesignspace

Expendingadesignspacewithoutreinventingthewheel (patentsearch) Patentsandcopyrights U.S.PatentOffice(USPTO)

DesignPatents UtilityPatents

Whendothepatentandcopyrightsexpire?

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AnintroductiontoUSpatentsystem

http://www.youtube.com/watch?v=vZ1SBP8ul1s

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Expandandprunedesignspace

Expandingthedesignspaceinnovativethinking Divergentthinking(whenwetrytoexpandthedesignspaceandgeneratedesignalternatives):

Outsidethebox Stretchtheenvelope

Convergentthinking:focusonthebestalternative(s)afterwehaveopenedupthedesignspacesufficiently.

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Expandandprunedesignspace

The635method 6 teammates,eachwritedown3 designsandpasstotheother 5teammatesforevaluation(nocrosstalk).

Comeupadesignbasedontheevaluations. Themethodcanbegeneralizedtothem3(m1)methodbystartingwithm teammembers.

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Expandandprunedesignspace

TheCsketchmethod Eachteammatemakesasketchwithannotations,andfollowsthe635method

Anexample:twosketchesoftheDanburyarmsupport

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Expandandprunedesignspace

TheCsketchmethod(continue) Importantnotes

Onannotation:clearandeasyreadnotes

Onproportion:sketchongraphpaper

Typeofsketches Orthographic(A) Axonometric(B) Oblique(C) Perspective(D)

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Expandandprunedesignspace

TheCsketchmethod(continue) Anexample:theDanbury

armsupport

Thesedrawingcanprovideagreatdealofinformationandareniceforpresentingtheworktoclients.

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Expandandprunedesignspace

Thegallerymethod Teammembersdeveloptheirindividual,initialideas,andposttheideasonboard.

Teammemberscommentontheideasinanopendiscussionforum.

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Expandandprunedesignspace Thinkingdivergently

Usesimilarity(bioinspired): Velcro: Velcrofastener plantseedsinnature

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Expandandprunedesignspace Thinkingdivergently(continue)

Usenewtechnologies: CT,MRI Anexample:theexpandablecoronarystent(thestentclearlyissimilarinbothintentandfunctiontothescaffoldingerectedtosupportwallsinminesandtunnelsastheyarebeingbuilt.

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Selectthepreferreddesign

Aftergettingseveralfeasibledesigns,weneedtochoosethebest

Anumberofmethodsareavailable,suchas Pughselectionchart(numericalevaluationmatrices) Theweightedbenchmarkchart Thebestofclasschart

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Selectthepreferreddesign Thenumericalevaluationmatrices

Thebeveragecontainerexample Usexasviolationofconstraints Usenumericalnumberasobjectivescore

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Selectthepreferreddesign Theprioritycheckmarkmethod

Useasprioritymarks 0=lessthan50marksand1=morethan50marks

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Selectthepreferreddesign Thebestofclasschart

Use1asthebest Use2asthesecondbest

(Foreachobjective,weassignincreasingscorestoeachdesignalternativethatrangefrom1forthealternativethatmeetsthatobjectivebest,2tosecondbest,andsoon,untilthealternativethatmettheobjectiveworstisgivenascoreequaltothenumberofalternativesbeingconsidered.)

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Designexample TheDanburyarmsupportexample

Morphchart

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Designexample TheDanburyarmsupportexample

Morphchart2

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Designexample TheDanburyarmsupportexample

Thetwodesignprototypes

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Questions?

Chapter 6: Design Modeling, Analysis, and Optimization(Learning objectives)

- Learnhowtomodeladesign- Learnhowtooptimizeadesign