外文资料--Product modularization for life cycle engineering.pdf

RoboticsandComputerIntegratedManufacturing15(1999)387401ProductmodularizationforlifecycleengineeringP.Gu!,*,S.Sosale!DepartmentofMechanicalandManufacturingEngineering,TheUniversityofCalgary,2500UniversityDrive,Calgary,Alberta,CanadaT2N1N4ImperialRubber,Ltd.,Edmonton,CanadaReceived24January1999；receivedinrevisedform15July1999；accepted10August1999AbstractModularproductsconsistofdetachablemodules,whichcanbemanufactured,assembled,andservicedseparately.Someofthemodulesmaybereusable,recyclableorre-manufacturableuponproductretirement.Thus,modulardesigncanprovidebenetstomanyaspectsofproductlifecycle.Thispaperpresentsanintegratedmodulardesignmethodologyforlifecycleengineering.Themethodologyconsistsofthreephases:problemdenition,interactionanalysisandmoduleformation.Themethodologyidentiesthefactorsrelatedtothedesignobjectives,relatesthesefactorstodesigncomponentsthroughinteractionanalysis,andclusterscomponentsintomodules.Twocasestudiesalongwithdetailedanalysisareprovidedtoillustratethemethodologyandthealgorithms.(1999ElsevierScienceLtd.Allrightsreserved.1.IntroductionModulardesignaimstodevelopproductarchitectureconsistingofphysicallydetachableunits(modules).Therearemanyadvantagesformodularproducts.Forexample,bycarefullymodularizingaproduct,thede-signsfortheearliermodelscanbeusedinanewmodelwithoutanychanges.Modulardesigncanalsohelpincreatingarangeofproductswithminorvariances.Additionalandauxiliarymodulescouldbeaddedtoaproducttocreatenewmodels.Modulardesignalsoallowssomecomponentstobeusedacrossproductvariantsandproductlinesduetostandardizationofthefunctionsandinterfaces.Recentstudyindicatedthatafterproductsareretired,someofthemodulesmightbereusable,orremanufacturable.Infact,modulardesigncancreatebenetsformanyaspectsofaproductlifecyclesuchasdesign,assembly,servicesandrecycling1,2.Thus,thereisaneedfordevelopingasystematicap-proachformodulardesignrelatingtoproductlifecycleengineering.Researchinlifecycleengineeringandcon-currentengineeringhassuggestedthatthemostimpor-tantdecisionsbemadeatthedesignstages38.*Correspondingauthor.E-mailaddress:guenme.ucalgary.ca(P.Gu)Therefore,productdesign,modellingandintegrationhavereceivedsignicantattentions9,10.Theobjectiveofthisresearchistodevelopanewmodulardesignmethodologytoaddressproductlifecycleconcernsatthedesignstage.Toachievethedenedlifecycleengineeringobjectivesthroughmodulardesign,therelationshipsbetweentheobjectivesandthemodulesshouldbeestablished.Asproductfunctionsarerealizedbyphysicalstructures,therelationshipsbetweenfunctionsandphysicalsolutionsshouldalsobedetermined.Essentially,modulardesigndecomposesaproductorgroupscomponentsintosepar-atemodules.Specialcaremustbetakentoensurethatseparationormergerofcomponentsdoesnota!ecttheintendedfunctionsoftheproduct.Thisrequiresthecon-siderationoffunctionalandphysicalinteractionsamongcomponents.Functionalinteractionsareusuallyexpressedintheformoftheexchangeofmaterial,energyand/orsignal.Theycanbeextractedfromthefunctionalstructureoftheproduct.Whenmodulesthatexchangethefunctionoperandsareseparated,specialprovisionsareneededforinterfacing；otherwisetheexpectedfunctionsmaybea!ected.Physicalinteractionsrefertospatialandgeometricalrelationships.Theyincludeattachment(physicalcontacts,xationsandstops,joints,fasteners,couplings,weldsandthelike),positioning(relativedistanceoranglebetween0736-5845/99/$-seefrontmatter(1999ElsevierScienceLtd.Allrightsreserved.PII:S0736-5845(99)00049-6components,alignmentincludingcoaxial,collinear,par-allel,perpendicularand#ushalignments),motion(cam-controlledobjects,trajectoryofjointsandend-e!ectors,etc.)andcontainment(ponentscontainedwithinthesamehousing).Thesephysicalandstructuralcon-straintsmustbeconsideredwhencomponentsaregroupedintomodules.Forproductassembly,productarchitectureshouldbedesignedtoensuree$cientassemblyprocessandquality.Di!erentmodularizationofaproductwilldirectlya!ectassemblyprocedures,assemblye$ciencyandcosts,espe-ciallylargestructureassembly11.Modularizationwillallowmodulesproduced,assembledandtestedinconve-nientlocationswithequipment,toolsandexpertise.Forproductreuseandrecycling,di!erentcomponentsofaproductmayhavedi!erentlifeduration.Whenaproductretires,theremaybesomeusablecomponents,andsomecomponentsmayberecoveredbyre-manufac-turing.Modulardesigncangroupthesecomponentsintoeasilydetachablemodulessuchthattheycanbeeasilyreusedorremanufactured.Forrecycling,materialcompatibilityshouldbecon-sideredasdi!erentmaterialswhichmayrequiredi!erentrecyclingordisposalmethods.Amodularproductcanfacilitatetheseparationandsortingofdi!erentmaterialsforproperrecyclingordisposalprocesses.Asaconcept,modulardesignhasbeenexploredbymanyresearchers1113.Variousdesignmethodshavebeenproposed.Themethodsofusingfunctionalstruc-turesformodularizationcomposedmodulesbygroupingthefunction-relatedelementstogether1315.EppingerandPimmler16usedphysicalrelationsformoduledesign.Erixon17proposedtousequalityfunctiondeployment(QFD)tomodularizeaproduct.Hillstrom12applieddesignaxiomstoevaluatetheinterfacesamongmodules.Mistreeetal.18demonstratedwithanexamplethatthereisarelationshipbetweentheinde-pendenceamongmodulesandreducinginteractionsbetweenthem.KusiakandHuang19proposedanapproachformodularizingaproductbyconsideringthecostsandperformanceofaproduct.Tomodularizeaproduct,clusteringalgorithmsareoftenused.EppingerandPimmler16usedaheuristicswappingalgorithmtoclustercomponentsintomodules.Newcombetal.20usedtheclusteringalgorithmde-velopedbyKusiakandChow21toidentifymodulesinaproduct.Kusiakandco-workershavedevelopedsev-eralclusteringalgorithms,whichcanbeusedforcom-ponentclustering2224.Thispaperisorganizedasfollows:Thefollowingsectionintroducesthelifecycleengineeringobjectivesofmodulardesign.Theproposedmethodologyisthenprovided.Todemonstratethemethodologyandtheal-gorithms,twocasestudiesaregiveninthefollowingsection.Thenalsectionisthediscussionsandthecon-clusions.2.ProductlifecycleobjectivesofmodulardesignAproductlifecycleembracesanumberofissuesincludingdesign,manufacturing,assembly,testing,shipping,distribution,operation(use),services,reuse,re-manufacturing,recyclinganddisposal.Ideally,amodulardesigncanachievealltheselifecycleobjec-tivessimultaneously.Inreality,di!erentobjectivesmayrequiredi!erentmodulestobeformed.Consequently,con#ictsmayoccur.Acompromiseisoftenrequiredformakingdesigndecisions.Thefollowingisalistofthemodulardesignobjectivesrelatingtoproductlifecyclebenets.1.Dividingdesigntaskforparalleldevelopment.Designofcomplexproductsmayrequiredesignteamsconsistingofexpertsfromdi!erentdisciplines.Sequentialdevelop-mentofsuchproductsmaytakealongtime.Bybreakingdowntheoveralldesignanddevelopmenttaskintosimplersub-tasksandproperlydeningtheinterfacesbetweenthesub-tasks,designteamscancarryoutthesub-tasksinparalleltoreduceproductdesignanddevel-opmenttime.2.Productionandassemblyimprovement.Modulesareessentiallyindependententitiesforaproductwithde-nedinterfaceswithothermodulesandcomponents.Modulescanbemanufacturedseparatelyindi!erentlocationstofacilitateproductionprocessesandexpertise,andtooptimizeequipmentutilization.Productarchitecturea!ectsassemblye$ciencyoftheproduct.Di!erentscenariosofmodularitymayresultindi!erentassemblyprocedureswithdi!erentassemblytimesandcosts.Incomparisonwithintegralarchitec-turesofproducts,especiallyforlarge,complexproducts,modulararchitectureallowsseparatemodulestobeas-sembledinthemostconvenientlocationsandthenputtogethertoreducethetotalassemblytimeandcosts.3.Standardization.Variousmodelsofproducts(e.g.afamilyofproducts)mayhavesomeidenticalfunctionsintheirfunctionalstructures.Thesefunctionscanberealizedbysimilarorevenidenticalphysicalstructures(modules).Thesecommonmodulescanbestandardizedandproducedinlargerbatchsizestoimproveproduc-tione$ciencyandqualityandreducecosts.Italsoen-hancesthestandardizationofacompany.4.Services.Productsusuallyrequirebothpreventivemaintenanceandrecoveryrepairs.Di!erentcomponentsofaproducthavedi!erentmaintenancefrequenciesandrepairrequirements.Bygroupingcomponentsintoeasilydisassemblemodules,faultanalysisandmaintenanceoftheproductsaremoreeasilyfacilitated.Whenafailureoccurs,thefaultymodulecanbetemporarilyreplaced,thefaultypartswithinthemodulearerepaired,andthenthemoduleisreturnedtoservice.Themainconsider-ationsrequiredforserviceabilityarefrequencyoffailure,servicerequirements,meantimeofrepairs,frequencyofpreventiveservices,accessibilityofcomponents,costof388P.Gu,S.Sosale/RoboticsandComputerIntegratedManufacturing15(1999)387401replacements,andrepaircomplexityintermsofthespecialskillsortoolsrequired.5.Upgrading.Everyproducthasalifecycleandevent-uallyretires.Manyreasonscontributetotheretirementofaproductsuchascustomerdemandfornewmodelsandwearoftheproduct.Todayshighlycompetitivemarketandhighconsumerexpectationsdemandmanu-facturerstointroducenewmodelsinashortperiodoftime.Also,therapidlychangingtechnologyquicklymakesproductsobsolete,althoughtheyareusable(puters).Thetimeande!ortrequiredtointroduceanewproductmodelareusuallysubstantial.Onewaytofacilitaterapidintroductionofnewmodelsisthroughreuseoftheexistingdesignandproductionprocessesoftheoldmodelswithaslittlechangesaspossibleinordertoreducethetimeande!ortfornewmodeldevelopment.6.Reconxguration.Whenfunctionsoftwoproductsaresosimilar,onecanbeconvertedtotheotherbysmallmodications.Oftentheusersdonotneedorcannota!ord(cost,space,etc.)aspecialproductforaparticularfunction.Thecongurableproductscanaccommodatetheneeds.Bychangingthearrangementofafewmodulesoraddingoneormoremodules,therequiredfunctionsmayberealizedbytheexistingproduct.Anexampleofthistypeofmodularityisrecongurablemachinetools.Byaddinganauxiliaryattachment,averticalmillingmachinecanbeusedforhorizontalmillingoperations.7.Recycling,reuseanddisposal.Di!erentcomponentsofaproductmayhavedi!erentlifeduration.Whenaproductretires,theremaybesomeusablecomponents.Modulardesigncangroupthesecomponentsintoeasilydetachablemodulessuchthattheycanbeeasilyreused.Forrecycling,materialcompatibilityshouldbeconsideredasdi!erentmaterialsmayrequiredi!erentrecyclingordisposalmethods.Amodularproductcanfacilitatetheseparationandsortingofdi!erentmaterialsforproperrecyclingordisposalprocesses.8.Productvarietyandcustomization.Customersusu-allyhaveindividualtastesandpreferences.Itisdi$culttodesignandmanufactureasinglemodelofproductsthatcansatisfyallcustomers.Oftenaproductentersthemarketinvariousmodelswithslightlydi!erentfeaturesandoptionstosatisfycustomerdemands,whilethemainfunctionremainsthesame(e.g.camcorders).Thistypeofmodelvarietyisusuallyo!eredbymanufacturers(e.g.choiceofsedanorstationwagonforcars).Manufacturerscanalsocreatemodelsforindividualcustomers(e.g.custom-madebicyclesandcomputers).Amodularprod-uctcanprovidecustomerswithchoiceofmodelsthroughre-arrangingafewoptionalmodules.Theaboveisalistofproductlifecycleobjectivesandbenetsthatmodularproductscanprovide.Mostlikely,itisnotpossiblethatallofthebenetscanbeachievedsimultaneously.Productdesignersanddevelopersshouldidentifythemostimportantcharacteristicsoftheproductsandusethefollowingmethodologytoachievethem.3.TheproposedmethodologyAnewmodulardesignmethodologyisdevelopedthatconsidersvariouslifecycleengineeringobjectivessuchasassembly,maintenance,reuseandrecycling.Itisidealifamodularcongurationcanachieveallobjectives.How-ever,itisexpectedthatcon#ictsarise.Itisthedesignersresponsibilitytomaketrade-o!decisions.Modularde-signcanbeapproachedintwoways:(1)formmodulesbasedoneachobjectiveseparatelyandthenmaketrade-o!decisionsbetweendi!erentmodularcongurations,or(2)modularizeaproductbasedonaweightedaverageobjective.Theproposedmethodologycanbeusedforthebothways.Themethodologyconsistsofthreemainphases:problemdenition,interactionanalysisandmoduleformation.3.1.Phase1:problemdexnitionTheproblemdenitionincludesidentifyingthetypeandcharacteristicsofthedesignproblem,decomposingtheoverallproblemintosub-problems,anddeterminingtheobjectivesofmodularization,oneormoreoftheobjectivesasdiscussedintheprecedingsection.3.1.1.IdentixcationoftypeandcharacteristicsofthedesignproblemManydecisionsmadeduringdesignprocessdependonthetypeofdesigntasks.Thedesigntaskscanbedi!erentintermsofthedegreeoforiginalityofthedesign,thevarietyoftheproducts(asingleproductversusafamilyofproductswithsimilarfunctions),lifespanofdi!erentmodulesoftheproduct(e.g.existenceoflong-lastingandshort-lifemoduleswithintheproduct),andthescaleofthedesignproject(budget,productionrate).Fortheoriginaldesign,designknowledgeisintheformoffunctionsandthusthedecompositiondeterminesthefunctionalstructureoftheproduct.Foradaptivedesign(re-design)wherethephysicalsolutionisalreadyknown,thedecompositionistheidenticationofphys-icalcomponentsorsub-systemswithintheproduct(physicalstructure).Thedecompositionofaproductde-signintofunctionalandphysicalstructuresisaprerequi-siteformodularizingaproduct.3.1.2.IdentixcationofmodulardesignobjectivesAsmentionedintheprevioussection,aproductismodularizedforvariousobjectives.Forexample,foralargeandcomplexproductassemblythatconsistsofthousandsofpartsandhasashortdeliverytime,modularizationforassemblyisimportant.P.Gu,S.Sosale/RoboticsandComputerIntegratedManufacturing15(1999)387401389Fig.1.Thehierarchyofobjectivesandrelevantfactors.Table1StandardrelationshipfortwocomponentsNo.TypeofrelationshipInteractionvalueRelationship(forparticularobjective)1Verystrong10Firmconnectionandhighrelationship(functionallyinseparable)2Strong8Mediumconnectionbuthighrelationship3Mediumstrong6Firmconnectionandmediumrelationship4Medium5Mediumconnectionandmediumrelationship5Mediumweak4Looselyconnectedandmediumrelationship6Weak2Notadjacentrelationshipwithitsadjacentcomponent7No0NorelationatallSub-assemblies(modules)canbepreparedinparallelandthenassembledintothenalproduct.Inanothersituation,whenafamilyofsimilarproductsistobemade,modulardesignforstandardizationcanhelpcreatecommonmodulestoreducecomponentvarietyandcostsofproductdesignandmanufacturing.Also,modulardesignobjectivesmaybepursuedindividuallyorintegratedassingleobjectiveusingtheweightedaver-ageapproach.3.2.Phase2:interactionanalysisAllmodulardesignapproachesattempttoclustercomponentsintomodulessuchthatinteractionsarelo-calizedwithineachmoduleandinteractionsbetweenmodulesareminimized.3.2.1.IdentixcationofrelevantfactorsEachobjectiveofmodulardesigndemandsasetoffactorstobeconsidered.Checklistshavebeendevelopedtohelpdesignersidentifyrelevantinteractionfactorsforeachoftheobjectives.Forexample,thelifeexpectancyofcomponentsisamainfactorforreuse.Eachinteractionfactorcanbedecomposedintosub-factors.Forexample,thephysicalfactorincludessub-factorsofcontact,alignmentandcontainment.Toevaluatetheinteractionsfortheobjective,valuesforeachinteractionareassigned.Thisformsahierarchyofobjec-tives,factorsandsub-factorsforinteractionanalysis(Fig.1).Atthelowestlevelfortheobjectives-factors-sub-factorsahierarchy,thevaluesofinteractionsamongallcomponentsmustbedetermined.Thesevaluesaretabulatedi