Chapter 1 - INTRODUCTION TO ENGINEERING DESIGN PROCESS - PART 1.pdf

Engineering Design

1. INTRODUCTIONTO
ENGINEERINGDESIGNPROCESS
CHAPTER1

2. COURSELEARNINGOUTCOMES(CLO) :
Uponcompletionofthiscourse,studentsshouldbeableto:
1.CLO1:Applytheconceptofdesignprocess,stressanalysisandmechanical
jointinanengineeringproduct.(C3,PLO1)
2.CLO2:Implementengineeringdesignprocessonprojectdesigntakinginto
designconsideration,ergonomicfactorsandmaterialselection.(C3,PLO3)
3.CLO3:Buildsapartorproductin3Dmodellingbasedonprojectdesign.(P4,
PLO5)
4.CLO4:Adoptdesignregardingtotheenvironmentandsustainability.(A3,
PLO7)

3. WHATISENGINEERINGDESIGN?
•AccreditationBoardforEngineeringandTechnology(ABET)definition:
•“Engineeringdesignistheprocessofdevisingasystem,component,orprocess
to meetdesiredneeds.”
•Itisadecision-makingprocess(ofteniterative),inwhichthebasicsciences,
mathematics,andengineeringsciencesareappliedtooptimallyconvertresources
tomeetastatedobjective
•thefundamentalelementsofthedesignprocessistheestablishmentofobjectives
andcriteria,synthesis,analysis,construction,testing,andevaluation.

4. DESIGNLEVELS
3stagesofdesign:
1.Adaptivedesign
2.Developeddesign
3.Newdesign

5. ADAPTIVEDESIGN
Thedesigner’sworkwillbeconcernedwiththeadaptationofexistingdesigns.
Therearebranchesofmanufacturinginwhichdevelopmenthaspracticallyceased,
sothatthereishardlyanythingleftforthedesignertodoexceptmakeminor
modifications,usuallyinthedimensionsoftheproduct.
Designactivityofthiskinddemandsnospecialknowledgeorskill,andthe
problemspresentedareeasilysolvedbyadesignerwithordinarytechnicaltraining.
Example:washingmachine.
Thishasbeenbasedonthesameconceptualdesignforthelastseveralyearsand
variesinonlyafewparameters,suchasitsdimensions,materials,anddetailed
powerspecifications.

6. DEVELOPMENTDESIGN
•Thedesignerstartsfromanexistingdesign,butthefinaloutcomemaydiffer
markedlyfromtheinitialproduct
•Example:television
•Traditionaltube-basedtelevisiontothemodernplasmaandLCDversions

7. NEWDESIGN
themostdifficultlevelinthatgeneratinganewconceptinvolvesmasteringallthe
previousskillsinadditiontocreativityandimagination,insight,andforesight
Example:automobile,airplane

8. CHALLENGESOFENGINEERINGDESIGN
well-publicizeddisastersassociatedwithengineeringsystemsareasfollows:
1.TheChernobylnuclearpowerplantdisasteroccurredin1996.Accordingtothe
WorldHealthOrganization(WHO),thisleadtotheevacuationandresettlement
ofover336,000people,56directdeaths,4000thyroidcancercasesamong
children,andapproximately6.6millionpeoplehighlyexposedtoradiation.

9. CHALLENGESOFENGINEERINGDESIGN
well-publicizeddisastersassociatedwithengineering
systemsareasfollows:
TheChallengerspaceshuttleexplodedin1986afteranO-
ringsealinitsrightsolid-rocketboosterfailed.Thiscauseda
flameleak,whichreachedtheexternalfueltank.Thespace
shuttlewasdestroyedin73secondsaftertakeoff,andall
crewmembersdied.

10. REASONOFFAILURESINMOST ENGINEERING
DESIGN
1.Incorrectoroverextendedassumptions
2.Poorunderstandingoftheproblemtobesolved
3.Incorrectdesignspecifications
4.Faultymanufacturingandassembly
5.Errorindesigncalculations
6.Incompleteexperimentationandinadequatedata
collection
7.Errorsindrawings
8.Faultyreasoningfromgoodassumptions

11. SYSTEMATICDESIGNPROCESS
1.Requirements
Identifyingcustomerneeds
Marketanalysis
Defininggoals
2.Productconcept
Establishingfunctions
Taskspecification
3.Solutionconcept
Conceptualization
Evaluatingalternatives
4.Embodimentdesign
5.Detaileddesign
6.Experiment
7.Marketing

12. WAYSTODESIGNADEVICE
1.Evolutionarychange
Aproduct isallowedtoevolveover aperiodoftimewithonly slightimprovement.This
isdonewhenthereisnocompetition.Thecreativecapabilitiesofthedesignerare
limited.
2.Innovation
Rapidscientificgrowthandtechnologicaldiscoveriesaswellascompetitionamong
companiesfortheirsliceofthemarkethaveplacedagreatdealofemphasisonnew
products,whichdrawheavilyoninnovation.Thecreativeskillsandanalyticalabilityof
thedesignengineerplayanimportantrole.
3.Invention

13. DESIGNPROCESSMAP

14. REQUIREMENTS
IdentifyingCustomerNeeds
Sourcesoftheneedfornewdesign
Clientrequest
Modificationofexisting design
Generationofa newproduct
Example:Compressionratio

15. REQUIREMENTS
Marketanalysis
Sourcestodeterminemarketavailability
Technicalandtradejournals
Abstracts
Researchreports
Technicallibraries
Catalogueofcomponentsuppliers
The internet

16. REQUIREMENTS
DefiningGoals
Thedesignerdefineswhatmustbedonetoresolvetheneeds
Customerneedsdoesnotequaltoproductspecification
Thedesigner’sfunctionistoclarifythecustomerdesignrequirements
Example

17. PRODUCTCONCEPT
Establishingfunctions
Recognizethegeneralityoftheneedstatementandwheretheproblem/need
standsinthewholesystem
Oftenthefunctionwillbedividedintosubfunctionandtheywilldefinethe
requirementsoftheartifact.

18. PRODUCTCONCEPT
Taskspecification
Requiresthedesignertolistallpertinentdataand
parametersthattendtocontrolthedesignandguide
ittowardsthedesiredgoals
Italsosetslimitsontheacceptablesolutions
Itshouldnotbedefinedtoonarrowly,anditcannot
betoobroad

19. SOLUTIONCONCEPT
Conceptualization
Theprocessofgeneratingalternativesolutionstothestatedgoalintheformof
conceptsrequirescreativeability
Theconceptualizationstartswithgeneratingnewideas

20. SOLUTIONCONCEPT
Evaluatingalternatives
Inthisstage,thedesignermustreviewthemarketanalysisandthetask
specificationsasheorsheengagesintheprocessofinnovationandcreativity
Thisactivityusuallyrequiresfree-handsketchesforproducingaseriesof
alternativesolutions

21. SOLUTIONCONCEPT
•Embodimentdesign
Oncetheconcepthasbeenfinalized,thenextstageisknownastheembodiment
design
Thiswheretheproductthatisbeingdesignedbeginstotakeshape
Thisstagedoesnotincludeanydetailsyet(nodimensionsortolerances,etc.)but
willbegintoillustrate:
acleardefinitionofapart
howitwilllook
howitinterfaceswiththerestofthepartsintheproductassembly
Thisstageisseparatedfromboththeconceptualdesignandthedetailed
design inthatnewtechnologiescanreplaceoldonesbasedontheexactsame
concept

22. SOLUTIONCONCEPT
•AnalysisandOptimization
Onceapossiblesolutionforthestatedgoalhasbeenchosen,thesynthesisphase
ofthedesignhasbeencompletedandtheanalysisphasebegins
Thisisalsoknownas“detaileddesign”
Thisstageisputiniterativesequencingwiththeoriginalsynthesisphase
Analysisstartswithestimationandisfollowedbyorderofmagnitudecalculation
Estimationisaneducatedguessbasedonexperience

23. SOLUTIONCONCEPT
Experiment
Mock-up:
Themock-upisgenerallyconstructedtoscalefromplastics,wood,cardboard,andso
forth
Themock-upisoftenusedtocheckclearance,assemblytechnique,manufacturing
considerations,andappearance
Itistheleastexpensivetechnique,providestheleastamountofinformation,andis
quickandrelativelyeasytobuild
Model:
Thisisarepresentationofthephysicalsystemthroughamathematicalsimilitude

24. SOLUTIONCONCEPT
Experiment
•Fourtypesofmodelsareusedtopredictbehavioroftherealsystem:
a)Atruemodelisanexactgeometricreproductionoftherealsystem,builttoscale,and
satisfyingallrestrictionsimposedinthedesignparameters.
b)Anadequate modelissoconstructedtotestspecificcharacteristicsofthedesign.
c)Adistortedmodelpurposelyviolatesoneormoredesignconditions.Thisviolationis
oftenrequired whenitisdifficulttosatisfythespecifiedconditions.
d)Dissimilarmodelsbearnoapparentresemblancetotherealsystem,butthrough
appropriateanalogies,theygiveaccurateinformationonbehavioralcharacteristics.

25. SOLUTIONCONCEPT
Experiment
Prototype:
Thisisthemostexpensiveexperimentaltechniqueandtheoneproducingthegreatest
amountofusefulinformation
Theprototypeisthe constructed, full-scaleworkingphysicalsystem
Herethedesignersees:
iii.
i.hisorherideacometolife
ii.learnsaboutsuchthingsasappropriateconstructiontechniques,assemblyprocedures,work
ability,durability
performanceunderactualenvironmentalconditions

26. SOLUTIONCONCEPT
Marketing
Thisstagerequiresspecificinformationthatdefinesthedevice,system,or
process
Herethedesignerisrequiredtoputhisorherthoughtsregardingthedesignon
paperforthepurposeofcommunicationwithothers
Communicationisinvolvedinsellingtheideatomanagementortheclient,
directingtheshoponhowtoconstructthedesign,andservingmanagementin
theinitialstagesofcommercialization

27. SOLUTIONCONCEPT
•Marketing
•Thedescriptionshouldtaketheformofoneofthe
following:
Areportcontaining:adetaileddescriptionofthedevice,howit
satisfiestheneedandhowit works,adetailedassembly
drawing,specificationsforconstruction,alistofstandardparts,
a costbreakdown, andanyotherinformationthatwillensurethat
thedesignwillbeunderstood andconstructedexactlyasthe
designerintended.
Aflyercontainingalistofthespecialfeaturesthatthedesign
canprovide,advertisements, promotionalliterature,market
testing,andsoforth.

28. PROFESSIONALISMANDETHICS
Professionalengineers
•Engagesinanactivitythatrequiresaspecializedandcomprehensiveeducation
•Motivatedbyastrongdesiretoservehumanity
•Providesserviceswithhonesty,integrity,andmorality

29. PROFESSIONALISMANDETHICS
NationalSocietyofProfessionalEngineersCodeofEthics:MainSections
•RulesofPractice
1.Engineersshallholdparamountthesafety,health,andwelfareofthepublic.
2.Engineersshallperformservicesonlyintheareasoftheircompetence.
3.Engineersshallissuepublicstatementsonlyinanobjectiveandtruthfulmanner.
4.Engineersshallactforeachemployerorclientasfaithfulagentsortrustees.
5.Engineersshallavoiddeceptiveacts.