2.70/2.77 Week 1 - MIT - Massachusetts Institute of Technologyweb.mit.edu/2.70/Lecture...

2.70/2.77Week1Spring2017

AlexanderSlocumPappalardoProfesorofMechanicalEngineering

[email protected]

IntroducContotheclass

•  ReviewSyllabus–  Thefinalexamcanbeeasy!

•  Andifyouwillbelookingforajob,youwantit!

•  Mostgoodemployersthesedaysusetechnicalinterviews!

•  IntroducConslidestosetphilosophyofcourse

•  Diveintoprecisiondesign!–  WewillbeusingOMAXAbrasive

WaterjetMachiningCentersasacasestudythroughouttheclass•  AlexhelpedstartOMAXandhasdonealotofdesignworkon… J

ThisWeek1Theme:FoundaCons

•  Week1:•  Reading:FUNdaMENTALSTopics1,2,3,PMDChapter1•  Brainware:

–  Createyourwebsite(ifyouhavenotalready)•  Itshouldhavesec<onswhereyoupostyourweeklyBrainwareandHardwareassignments

–  FacebookorLinkedinareNOTacceptable.IfIhavetodealwithadver<sementsandworktogettheinfo….YOURFIRED!

•  Wordpress,GoDaddy,WIX…•  ExampleofasuperduperA++… hTp://aeram00.scripts.mit.edu/index/2-77/

–  Createaonepage“whitepaper”onthemachineyouwilldesign,build,testthissemester.–  Designasimpleplanarexactconstraint(EC)systemtoletauserexploresensiCviCesinfixturingaplanarobject

•  Youcannotjust“printit”:youhavetomakeit!–  Seek&GeekExploraCon

•  Hardware:–  Makewebsitefortheworkyouwilldointhecourse(itcanbeanewtabinyourcurrentpersonalwebsite)andsubmit

theURLtocoursestaff–  Makeyourplanarexactconstraint(EC)systemfrommaterialsyoucanobtainyourselfandgettogetherwithyour

peergrouptoplaywitheachother’ssystemsanddiscuss.•  Thissimpledeviceissomethingtokeepandcherish,andbringtointerviews….

–  YoushouldbeabletodemonstratefuncConingofyourArduinoboard,powersupply,andturnonalight,andideallybemovingasteppermotor(orgetonethisweekfromcoursestaffandhaveitrunningbynextweek).

–  Seek&GeekExploraCon

MakesureyoudothereadingsBEFOREclass(in

thisandallcourses)

NextWeek2Theme:FUNdaMENTALSofdeterminisCcdesign

•  Week2:•  Reading:FUNdaMENTALSTopics4,5,6,PMDChapter2•  Brainware:

–  DeterminisCcdesignbasedonsimplecheapelements(buildablefromstuffyoucanobtainyourself(thereisnobudgetormaterialssupplied):•  Structure,bearings,andcarriageforsimple“precision”linearmoConaxis.

–  Makesuretoleaveroomfortheactuator!–  Usespreadsheetstoassignerrors(errorapporConment)andcreatepreliminaryerrorbudgetsfor“best”

concepts…–  Usespreadsheetstoanalyzestructuralandmachineelementsyouplantousetoensuretheycanhandlethe

loads…•  Design(usethespreadsheet)athreegroovekinemaCccouplingtocoupleanythingyouwant(see

web.mit.edu/2.75forexamples)–  Youcannotjust“printit”:youhavetomakeit!

–  Seek&GeekExploraCon–  Updatewebsite

•  Hardware:–  MakesureyoureallyknowhowtocontroltheArduinocardfromyourlaptopandmakethe

steppermotormove–  MakeyourkinemaCccouplingandusealaserpointeracachedtoitthatprojectsdownthe

halltomeasurerepeatability.

Lesson1

•  Everythinghappensforareason…–  Ignoranceofthelaws(andpartsavailable)isnoexcuse

•  Hope&prayercanbegreatforpersonallife…–  BUTphysicsdoesnotcare…

"Iwishitwoulddawnuponengineersthat,inordertobeanengineer,itisnotenoughtobeanengineer"

SpanishphilosopherJoseOrtegayGassetin1939.

hcp://en.wikipedia.org/wiki/Jos%C3%A9_Ortega_y_Gasset

FromadverCsementforAlphasizingsolwareforgearboxes

2/8/17 ©2000AlexanderSlocum 6

“Youcan’talwaysgetwhatyouwantButifyoutrysome5meswellyoumightfind

Yougetwhatyouneed”

MickJagger&KeithRichards1969hcp://lyrics.all-lyrics.net/r/rollingstones/leCtbleed.txt

Get a clear notion of what you desire to accomplish, then you will probably get it �

�Keep a sharp look-out upon your materials: get rid of every pound of material you can do

without. Put yourself to the question, ‘What business has it there?’ � �

Avoid complexities and make everything as simple as possible ��

Remember the get-ability of parts

HenryMaudslay(1700’s,thefatherofmodernmachinetools)

♥Passion♥isaCatalystFOCUS:KeepYourEyeonthePrize


Maximize aquatic Avian linearity��

Maximize avian termination with a minimum number of projectiles ��

Lacerate Bovine growth byproduct ��

Minimize deceased Equine flagellation ��

Impactus maximus ad gluteus maximus ��Alex Slocum

♥Passion♥isaCatalystFOCUSYourEffort

“RandomResultsaretheResultofRandomProcedures” Geoffe Portes

♥Passion♥NeverStopBeingaKid!

2/8/17 ©2016AlexanderSlocum 1-8

"Enthusiasm is one of the most powerful engines of success. When you do a thing, do it with all your might. Put your whole soul into it. Stamp it with your own personality. Be active, be energetic, be enthusiastic and faithful and you will accomplish your object. Nothing great was ever achieved without enthusiasm"Ralph Waldo Emerson

Gen1

Gen2Gen3Topsecretdesigndevelopment!

GuardUnits

•  ANDyouCANhavefamily,career,fun!–  Bigsheetsofpaperandcrayons…

•  Createtogether!

Teamwork!

•  TeamsarecriCcal!(peerreviewgroups)

•  IndividualsarecriCcal!(yourproject)•  SolveChallengeswithPREPprocess

•  Individualsthenthinkandwrite/sketchideasinnotebooks•  IncludingapplyPREPtoidenCfying

problemtobesolved!•  Notebookstradedandeveryone

reviewseachothersworkandwritesconstrucCvecomments…

•  THENbrainstorm!•  TheChallenge:

•  Eachpersonin2.007willdesign,buildandtestaCNCdesk…•  Formpeerteamsof2-4…•  BecauseeachpersoncreaCngthe

samething,peerreviewwillworkreallywell…

92/8/17 ©2016AlexanderSlocum

FuncConalRequirements

(what)

DesignParameters

(How)

Analysis(Physics)

References(History)

Risks(Ouch!)

CounterMeasures(Ahhh!)

DeterminisCcDesignCycle:MANYdesignersareADHD&CDO…

Needameanstoorganizethoughtsyetbefreetozoomabout…


THEmostimportantkeytoPMD:ErrorApporConment:APrecisionHunCngLicense•  Axis_error_apporConment_esCmator.xls•  Beforeadesignerevenstartssketchingideasforamachine,idenCfy

thelevelofgoodnessrequiredofeachaxisandthecomponents

–  SavesalotofCmethinkingaboutcreaCveideasthatarenotlikelyviable


PrecisionMachineDesign(akaDeterminisQcDesign)Roadmap


DetermineFuncConal

Requirements

• Interfaces• Loads• Powerflows(I/O)

ErrorApporConmen

t

DevelopDesign

SCckFigurestodescribestrategiesandconceptsIdenCfyStructuralLoopsAppropriateAnalysisofelements

ErrorAnalysis

Error_Budget_Spreadsheet

Axis_error_apporConment_esCmator

Detaileddesign

Update&NewAnalysis

FuncConalRequirements•  CreateatableoftheFUNCTIONSthatneedtobeaccomplished

–  ItcanincludespecificaCons,butgenerallywordspreferred–  Listjustthemajoronestostart…

•  Donotfretoverdiscoveringeveryonetostart•  Thetablecanbeappended(peelingtheonion)

–  Itsimportanttousethetableasacatalysttogetmoving!•  Ideaswillcatalyzemoreideasandtableamendments…

–  Example:ThestartFRDPARRCtocreateabecer3Dprinter(FDM)•  Listapproachesthatcometomindasyoubegintofilloutthetable…


Strategies(thatcometomind)

FR DP A Ref Risk CM

Stackedmodularaxes

Desktop(lowcost)

footprint ExisCngprintersdieyoung

overconstraint

5yearlife F=kx overconstraint KinemaCcdesign

Cube,PKM .03m3workvolume

Smallfootprint,,goup

Skyscrapers,PKMs

Cube,PKM 0.1mmaccuracy

Abbe “Cube”designs

DeterminisCcDesign:AProcesstoDevelopaDesign

•  Faithandprayermaybegreatforpersonallife…..–  Peoplecare,physicsdoesnot!

•  HOWEVER,Forproducts:–  Everythinghappensforareason–  Physicsdoesnotgiveadamn–  Ergonomicsdoesnoteither!–  MarkeCng,service…alsohastobewellthoughtout

•  The“scienCfic”methodcanbethoughtofasthe“DeterminisCcMethod”–  Observe–  Postulate/hypothesis–  Designexperiment/soluCon–  Thoughts,sketchesdrivenbyobservaCons,analysis…–  Buildandtest–  Checkagainsthypothesis–  Iterate

•  IdeallyasfewCmesaspossible•  Bewarebudgets!

–  Time,money…


Hackathons


DeterminisCcDesign:Coarse-to-Fine:StrategiesConceptsModulesComponents

•  DeterminisQcDesign:Everythinghappensforareason

•  DeterminisQcDesignleavesLOTSofroomforthewildfreecreaCvespirit,andLOTSofroomforexperimentaConandplay

•  DeterminisQcDesignisacatalysttofunnelcreaCvityintoasuccessfuldesign

•  ItisOKtoiterate…

–  Agoalistoneverhavetobacktrack•  Agoodengineerknows

whenitsCmetoletgo…

Strategy:Overallapproachtoaccomplishthegoal

Concept:Designtoimplementthestrategy

Module:AmajorpartofthedesignthatexecutesacertainfuncCon

Component:Anindividualelement

FuncConalRequirements

(what)

DesignParameters

(How)

Analysis(Physics)

References(History)

Risks(Ouch!)

CounterMeasures(Ahhh!)

FRDPARRCDeterminisCcDesignCycleYoucanstartthecycleanywhere,BUTyoumustvisiteachnode!

Coarse-to-fineandsomeQmesnodesblankunQllaterincycle!

“FredPark”J


2/8/17©2016AlexanderSlocum 1-17

DeterminisCcDesign:FRDPARRCFunctional Requirements (Events) Words

Design Parameters (Idea) Words & Drawings

Analysis Experiments, Words, FEA, Equations, Spreadsheets…

References Historical documents, www…

Risk Words, Drawings, Analysis…

Counter-measures Words, Drawings, Analysis…

A list of independent functions that the design is to accomplish.

Different ways to accomplish each FR.

Physics, Economics… EACH DP’s FEASABILITY MUST BE PROVEN. Analysis can be used to create DPs!

Anything that can help develop the idea including personal contacts, articles, patents, web sites….

High, Medium, Low (explain why) risk of development assessment for each DP

Ideas or plan to mitigate each risk, including use of off-the-shelf known solutions

• ToactuallyusetheFRDPARRCTable:• Createtablesforstrategies,concepts,modules,components…• Theprocessrepeats!

TheFRDPARRCtableisanpowerfulcatalysttohelpmakesureyoudonotgooffonwildshinysquirrelchases!

UseReciprocity:1/R=CM1/L=J


PMDPhilosophy:Coarse-to-FineDeterminisQcDesignProcessStrategy 1 – All axes linear

Strategy 2 – All axes rotary

Strategy 3 - Hybrid

Concept 3 – stacked axes (work fixed)

Concept 2 – PKM (work fixed)

Concept 1 – stacked axes (work & print head move)

Module 2 – overall structure

Module 1 – linear axes

Module 3 – enclosure/environment

Module Idea 1 – screw driven

Module Idea 2 – belt driven

Module Idea 1 – open frame

Module Idea 2 – closed frame (cube)

Module Idea 1 – light curtains

Module Idea 2 – doors

Component 1 – bearings: type and arrangement

Component 2 – actuator: belt, motor, gearbox

Component 3 – structures: stock or custom extrusion

Component 4 – sensors: linear or rotary encoder, T...

Element 1 – linear (carriage)

Element 2 – rotary (actuator)

DesignaFDM3Dprinter

ErrorA

pporCo

nmen

thun

Cnglicen

se


FRDPARRCandFunnelingExample:DinnerFunctional

Requirements Design

Parameters Analysis References Risk Counter -

measures Within budget < $20 Weekly salary -

total already spent Wallet Can't buy new CDs

Eat cheaper or at home

Easy to get to Within 3 miles Bikable distance in 10 minutes Past experience No bike parking Walk, order in or

eat at home Fast Within 1 hour Time now - work

left to do Watch Won't finish homework

Ask friend for help

Tasty Eat at home

Take Out Delivery Eat Out

Brain storm for ideas

Online menus, refrigerator

contents Nothing tasty at

home Eat out!

In-ClassPersonalAssesment

•  2.001(mechanicsofsolids)iscriCcaltoallmachinedesign–  Tounderstandhowmuchfolksremember/canfigureout

•  EachstudentpleaseanswerquesConstobestofability–  Workproductwillbecollectedattheendofclass,graded,returned,andshouldhelpthestudentidenCfyareastostudy…

•  ThequesConswillhelpyoustartthinkingaboutyourtermproject–  Stresses&deflecConsinthesupportstructureofaplaxormthatsupportsaworksurface…

The“opportunity”

•  Deskacachedtowall–  StructurecanClevered–  Definepointforceload(elbows!)–  Definedistributedload(stuffpiledon)–  DrawFreeBodyDiagram–  Determine

•  forcesandmoments•  Stresses•  deflecCons

Wall

Supp

ort

structure

(with

verCcal

linear

moC

on)

Hint:forfirstorderassessment,whatshouldtheconstraintsbeconservaQvely

modeledas?

2.70/2.77 Week 1 - MIT - Massachusetts Institute of Technologyweb.mit.edu/2.70/Lecture...

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Transcript of 2.70/2.77 Week 1 - MIT - Massachusetts Institute of Technologyweb.mit.edu/2.70/Lecture...