preparation of stress analysis reports (8594001)

8/8/2019 Preparation of Stress Analysis Reports (8594001)

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- AS RELEASED 12/22/2009

REVISION HISTORY

REV DESCRIPTION OF CHANGE DATE APPROVED

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

LYNDON B. JOHNSON SPACE CENTER HOUSTON, TEXAS

PREPARATION OF

STRESS ANALYSIS REPORTS

SCALE: NONE AOD, CC3 SHEET: 1 OF 14

SIZE CAGE CODE DWG NO REV

A 21356 -8594001


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8594001, Rev -

Preparation of Stress Analysis ReportsRev-, December 2009

-1.'*t

Approved By

/ 74"rqSon Nguyen

Lead, Aircraft Engineering

David McMahonAircraft Engineering

Chief, Aircraft Engineering Branch

Poge 2 of t4


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1.0 IntroductionThisdocumentestablishesrequirementsforformalstressanalysisreportspreparedfortheNASA

JohnsonSpaceCenter,AircraftOperationsDivision(AOD).Itplacesspecialemphasisontheimportance

ofwritingaccurate,concise,andreadablereportsthatstandaloneandcanserveasformal

documentationforthestrengthofthestructure.Awelldocumentedstressanalysisisonethatcanbe

readandunderstoodbyanyonethatisknowledgeableinthefieldofstructuresbutisnotfamiliarwith

thestructurebeinganalyzed.

2.0 ScopeThisdocumentisapplicabletostressanalysisreportspreparedfortheJohnsonSpaceCenterAircraft

OperationsDivision.Thisdocumentappliestotheanalysisofaircraftstructures,installedequipment,

payloads,andgroundsupportequipment.

3.0 Analysis3.1CoverageAllloadcarryingstructureswhosefailurecouldresultindamagetotheaircraftorinjurytopersonnel

shallbesubstantiatedbyastressanalysis.Theanalysisshallcoverthehardwareinanasbuiltandas

installedconfiguration.Includedinthisanalysisshallbeallstructures,fasteners,welds,orbondsinthe

primaryloadpath.

3.2DetailsEachpartshallbeanalyzedbasedonthedesignintentandloadenvironmentofthestructure.The

analyst

shall

ensure

that

all

failure

modes

and

worst

case

combined

stresses

have

been

examined.

Thefollowingisalistofexamplestressanalysiscategories.Note,thislistisprovidedforreferenceonly;

itistheresponsibilityofthestressanalysttodeterminewhattypesofanalysesshouldbeperformedfor

agivenstructure

a) Bending,flexuralshearand/ortorsionanalysisofabeam,frame,rib,shaft,orringofvariousopenorclosedsections

b) Plateandshellanalysisc) Beamonanelasticfoundationd) Pressurevesselanalysis(Note:pressurevesselanalysisrequiresreviewandapprovalbythe

NASAFracture

Control

Team.

Contact

NASA

Aircraft

Engineering

for

pressure

vessel

analysis

requirements)

e) Alltypesofstabilityanalysisincludinggeneralandlocalstabilityofplates,skins,webs,shells,webshearbucklingordiagonaltension,localbucklingorcripplingofcompositeshapes,column

stability,andbeamcolumnstability

f) Analysisofcomposite,honeycomb,andreinforcedmaterialsg) Largeelasticdeformations,geometricalnonlinearity,andgappinganalysis


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h) Nonlinearanalysisbeyondtheelasticrangeofthemateriali) Vibration/flutteranalysis

j) Dynamic,impact,andfatigueanalysisk) Stressconcentrationandfractureanalysisl) Crackgrowthanalysism) Machinecomponents(spring,gear,shaft,clutch,brake,ropes,belts,chains,cables,etc.)

analysis

n) ThermalstructuralandotheranalysisForfasteners,fittings,andconnections,thestressanalysismayfallintoanyofthefollowingcategories:

a) Boltedjoint,fitting,spliceplate,andboltgroupanalysisb) Rivetedjointandconnectionanalysisc) Lug,pin,andbushinganalysisd) Boltpreloadandinstallationtorqueanalysise) Weldedjointanalysisf) Bonding,adhesive,andfrictionanalysisg) Linearandnonlinearresidualstressanalysish) Tolerance,interference,mismatch,thermalandotherstructuralanalysis

4.0 ReportFormatThestressanalysisreportshallcontainthesectionsshowninFigure1.Allsectionsshallbeclearly

labeledandallreportpagesnumbered.Anexplanationofthecontentofthesesectionsfollows.

Figure1:StressReportOutline

TITLEPAGETABLEOFCONTENTSLISTOFSYMBOLSANDACRONYMS

1.0EXECUTIVESUMMARY2.0MINIMUMMARGINOFSAFETYSUMMARYTABLE3.0INTRODUCTION4.0MATERIALPROPERTIES&ALLOWABLESSUMMARY5.0COORDINATESYSTEMS6.0LOADSSUMMARY7.0CALCULATIONS8.0REFERENCES9.0APPENDIX


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TITLEPAGEThetitlepageofthereportshallincludeareportnumberandtitle.Itshallbespecific,unique,and

concise.Acronymsshallnotbeusedinthetitlewithoutdefinition.Thetitlepageshallincludearevision

blockforreportrevisions.AnexampletitlepageisshowninFigure4.

TABLEOFCONTENTSAtableofcontentsshallbeincludedinthereportlistingeachreportsectionandapplicablepagenumber.Itisacceptabletoomitthetableofcontentsforreportsshorterthanten(10)pages.

LISTOFSYMBOLSANDACRONYMSAllsymbolsandacronymsusedinthereportmustbedefinedandshowdimensionalunitsifapplicable.

Groupthesymbolsandacronymsseparatelyandarrangetheentriesinalphabeticalorderinthe

followingpriority.

a) Englishlettersb) Greeklettersc) Subscriptsd) Superscripts

EXECUTIVESUMMARYTheexecutivesummaryshallsummarizethemajorresultsandconclusionsinthereportsothatthe

readermaydeterminethesubstanceofthematerialanddecidewhethertoreadthereportfrom

beginningtoend.Thissectionshallclearlystatewhetherornotthestructuremeetsthedesign

requirements.Theexecutivesummaryshallalsoincludeanyrecommendationsbasedontheanalysis.

Thissectionshallcontainapictorialoverviewofthesystembeinganalyzedalongwithfiguresor

diagramsshowingasummaryofloadingandresults.Thisisprobablythemostreadsectionofthe

report.

MINIMUMMARGINOFSAFETYSUMMARYTABLEThissectionshallincludeatableshowingthecalculatedminimummarginsofsafetysummarizedina

tabularformat.Thistablegivesthereaderaquickreviewoftheresults.Exampletablesshowingthe

datathatshallbeprovidedisshowninFigure2andFigure3.Thesetablesmaybecustomizedtoadd

additionalrelevantdatabutshall,ataminimum,containthedatashown.Notethateachpartnumber

shallonlybelistedonceeventhoughtheremayhavebeenseveralmarginsofsafetycalculatedforeach

part.Therefore,thislistisaminimummarginofsafetysummaryandsignifiesthedesigncritical

condition.

INTRODUCTIONTheintroductionshallexplainthepurposeorobjectiveofthereport.Theintroductionshouldcontaina

listofthepartsbeinganalyzedandshouldalsoincludeanyhistoricalinformationthatwouldhelpthe

readerfurtherunderstandthecontextoftheanalysis.Ifthestructureisacomponentofalarger

assembly,thissectionshallindicatehowthecomponentbeinganalyzedfitsintotherestofthe

assembly.Otherrelatedanalysisreportsshallbereferencedinthissectiontoprovidethereaderwithan


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overallpictureofthecompleteanalysispackage.Thelengthoftheintroductionshouldbekeptasshort

aspossibleyetstillconveythenecessaryinformation.

MATERIALPROPERTIESANDALLOWABLESSUMMARYThissectioncontainsallthematerialallowablesthatareusedintheanalysistocalculatethestructure

marginsof

safety.

All

materials

used

in

the

analysis

shall

be

clearly

identified

(alloy,

heat

treat,

compositetype,etc.)alongwiththeapplicablematerialproperties.Thisisareferencesectionforthe

readersothathecaneasilydetermineifthecorrectallowablewasusedintheanalysistoobtainthe

marginofsafety.Thesourceoftheseallowableswillbeclearlyreferencedandreadilyobtainablebythe

reader.Reproducedpagesofmaterialmanualsandreferencesshowingtheallowableswillbe

acceptableprovidedthesepagesalsoshowthesource.

COORDINATESYSTEMSThecoordinatesystem(s)usedforloadsapplicationandcalculationsshallbedefinedinthissection.A

diagramshowingthecoordinatesystemorientationrelativetostructurebeinganalyzedandhowit

relatestotheaircraftcoordinatesystemshallbeprovided.

LOADSSUMMARYThissectionshallincludeasummaryofthecriticalloadsappliedtothecomponentbeinganalyzed.

Componentweightsandcentersofgravityshallalsobelisted.Dependingonthecomplexityofthe

structurebeinganalyzed,thissectionmayormaynotincludeadetailedloadsanalysis.Ifthestructureis

ofsubstantialcomplexityasdeterminedbytheanalyst,thedetailedloadsanalysisshallbeinaseparate

reportorintheappendix.Theloadsshallbelistedbyloadcaseinatabularformatshowingload

magnitudeanddirectionbasedonthespecifiedcoordinatesystem.Highlevelfreebodydiagrams

showingtheappliedloadsandreactionsforthegoverningloadconditionsshallbeprovidedinthis

section.Moredetailedfreebodydiagrams,ifapplicable,specifictoindepthanalysesshallbeprovided

inthe

calculations

section.

CALCULATIONSThissectioncontainsthedetailedanalysisofthestructuralcomponents.Allassumptionsusedinthe

analysisshallbeclearlydescribed.Inaddition,allcalculationunitsshallbeclearlyshown.Finalresults

shallshowmaximumstresses,deflectionsandotherpertinentdatalistedbyloadcase.

Sketches,Figures,andDiagrams

Thecalculationssectionshallincludesketches,figures,ordiagramstoillustratethepartsbeing

analyzed.Theanalysisshallbereadablewithoutreferencetodrawings.Thefollowinginformation

shallbeincluded:

a) Whatpartsarebeinganalyzedidentifyallpartsbypartnumberb) Wheretheyareintheaircraftorpayloadc) Wheretheexternalloadsared) Wherethereactionsare.Ifpractical,showafreebodydiagraminbalancewithappliedloads

andreactions

e) Showthepartdimensionsthatarereferencedintheanalysis


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f) LocatethesectionsanalyzedandreferenceaxesusingaconsistentcoordinatesystemAllAnalyses

Thefollowinginformationshallbeincludedforallanalyses:

a) Loadsandboundaryconditionsshallbeclearlydefined.Theloadpathasittravelsfromtheaircrafttothestructurebeinganalyzedshallbeclearlyidentified.

b) Allsketches,figures,diagrams,andplotsshallbeclearlydrawnandlabeled.c) Allcalculatedmarginsofsafetyshallbeclearlynoted(e.g.underlined,bold,boxed,etc.)All

resultsshallbepresentedusingaconsistentcoordinatesystem.Thecoordinatesystemshallbe

clearlyshownonallmodelandresultplots.

HandCalculations

Thefollowinginformationshallbeincludedforhandcalculations:

a) Everyequationshallbereferencedtoitssourcebysection/pagenumberandthesourcelistedinthereferencesectionofthereport.Itisacceptabletoomitreferencesforverybasicequations

thatwouldbecommonknowledgetoawideaudienceknowledgeableinstressanalysis.See

Figures5&6forexamplehandcalculations.

b) Componentloadsmaybeobtainedfromafiniteelementmodelandthenusedinhandcalculationstocomputestresses.Printoutsoftheinternalforcesobtainedfromthefinite

elementmodelshallbeprovidedintheappendix.

ComputerAnalyses

Thefollowinginformationshallbeincludedforcomputeranalyses:

a) ForFiniteElementAnalyses(FEA),thissectionshallincludeadescriptionofthemeshstrategy,boundaryconditions,loadapplication,andconvergencecriteria.

b) WhereFEAresultsareusedtocomputemarginsofsafety,astressplotshallbeprovidedwiththemaximumstresslocationandvaluenotedonthefigure.

c) FEAresultsshallbecrosscheckedviahandbookcalculationstoverifyFEAresultsarereasonable.ComponenttestingtoverifyFEAresultsisalsohighlydesirable.Thecrosscheck

processshallbeclearlydescribedinthereport.Thefollowingprovidesarecommendedchecklist

foritemstobereviewed:

a. Reactions(vs.handcalculatedfreebodydiagramvalues)b. Results(vs.handcalculatedstressesanddeflections)

Allrepetitiousandsimplecalculationsshouldbeomitted.Onesamplecalculationshallbeshownand

theremainingresultssummarizedbytabularorgraphicalform(suchcalculationsshouldbestatedas

typical).


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Acompletefileofunsubmittedbackupornotebookanalysesshallbemaintainedbythe

responsiblestressanalysispersonnelwithintheoriginatingorganization.Theseunsubmittedsupporting

analysesshallbesaveduntilthehardwarehascompleteditsdesignlife.

REFERENCESA

list

of

all

references

cited

in

the

report

shall

be

included

in

order

to

document

the

source

of

informationusedintheanalysis.Alldocumentsreferencedshallbereadilyobtainablebythereaderso

thattheycanbestudiedifadditionalinformationisrequired.ItcanbeassumedthattheNASAhas

accesstoallgovernmentspecifications,publishedtechnicalarticles,andpublishedbooks.However,it

shouldnotbeassumedthatNASAhasaccesstoContractors'internalletters,reports,orstressmanuals

sincetheseitemsareusuallyContractors'proprietaryinformation.Whenitemsofthistypeare

referencedinthestressanalysis,thepertinentdatashallbeincludedinthestressreport.Ifthisdata

cannotbeinsertedattheplaceinthereportwhereitisneeded(duetobulk)thenitshallbemadean

appendixtothereport.AsimplecurvetakenfromaContractors'stressmanualtoshowwherea

particularfactorcamefromisnotsufficientdocumentationtovalidatethefactorunlessthereis

sufficientinformation

written

directly

on

the

curve

to

show

how

it

was

generated;

i.e.,

boundary

conditions,assumptions,etc.

APPENDIXExamplesofitemsthatmaybeincludedintheappendix:

Drawingsandtechnicalinformation Technicalcorrespondence Finiteelementanalysismodelplots&results Stressmanualreferences Multiplecalculationresults Computerfiletable

5.0CheckingThestressanalysisreportshallbecheckedbyanapprovedrepresentativefromtheoriginating

organizationindependentofthereportauthor.Verificationofthefollowingshallbecompleted:

a) Numericalcalculations(equations,unitconversions,etc.)b) Methodofanalysis(analysistechniques,assumptions,etc.)c) Materialproperties(tensilestrength,yieldstrength,modulusofelasticity,etc.)d) Completenessofcoverage(allfailuremodesandloadconditionsinvestigated)e) FiniteElementAnalysis(analysisstrategy,geometry,mesh,mass,boundaryconditions,load

selection,loadapplication,reactions,&results)

f) Legibilityandreadabilityofanalysis


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6.0ReportSignaturesThereporttitlepageorsignaturepageshallinclude,ataminimum,thesignaturesbelow.Notethatthe

requiredsignaturesaredifferentforreportsgeneratedinternaltoNASAAircraftOperationsDivisionand

forreportsgeneratedbyorganizationsexternaltoNASAAircraftOperationsDivision.

RequiredSignatures

for

NASA

Aircraft

Operations

Generated

Reports

a) Author/Engineer(personwhopreparedreport)b) Stress(personwhocheckedstressanalysis)c) Authorization(personauthorizedtoapprovereportreleaseintoNASAconfigurationcontrol

system)

RequiredSignaturesforReportsGeneratedbyOrganizationsExternaltoNASAAircraftOperations

a) Author/Engineer(personwhopreparedreportfromoriginatingorganization)b) Checker/Stress(personwhocheckedstressanalysisfromoriginatingorganization)c) Approver(personauthorizedbyoriginatingorganizationtoapprovereportrelease)d) AODStress(NASAAircraftOperationsDivisionpersonwhoreviewedstressanalysis)e) AODAuthorization(NASAAircraftOperationsDivisionpersonauthorizedtoreleasereportinto

NASAconfigurationcontrolsystem)

ForreportsgeneratedbyorganizationsexternaltoNASA,theoriginatingorganizationshallsubmit

thereportwiththeAuthor,Checker,andApproverboxessigned.NASAshallthenreviewthereport

andsigntheNASAStressandNASAAuthorizationboxesforreleaseintoNASAsconfiguration

controlsystem.

7.0ReferencesThe

following

references

were

used

in

the

preparation

of

this

document:

1. InstructionsforthePreparationofStressAnalysisReports,JSC19652A,NASAJohnsonSpaceCenter,1987

2. CriteriaForPreloadedBolts,NSTS08307,NASAJohnsonSpaceCenter3. E.F.Bruhn,AnalysisandDesignofFlightVehicleStructures,19734. ThomasP.Sarafin,SpacecraftStructuresandMechanisms,FromConcepttoLaunch,2003


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Figure2:MinimumMarginofSafetySummaryTableDescription Analysis MinimumMargin

ofSafetyPartNumber Name Material FailureTheory AppliedLoad

(LoadCase) Yld.1 Ult.2

MSCZZD001001 Widget Ti6AL4V VonMises Fx=125lbs,

Tx=6000inlbs

(LoadCase1)

+.05 +.01

1 1M.S.

limit

strengthyield

ield =

y

2 1F.S.

M.S.limit

strengthultimate

ultimate

=

limit : thestresslimitiscalculatedbasedontheflightvehiclelimit

loads.Limitloadsarethemaximumloadsanticipatedontheflight

vehicleduringitslifetimeofservice.

F.S.: theFactorofSafetyvariesbasedonthetypeofaircraft,installed

location,material,

and

other

conditions.

Please

contact

NASA

Aircraft

Engineeringfortheapplicablefactorofsafetytouseinyourapplication.

ExampleChoices:

VonMises MaximumNormalStress Buckling Fatigue TsaiWu Other(describe)


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Figure3:FastenerMinimumMarginofSafetySummaryTableFastener Analysis FastenerForces Minimum

# FastenerLocation

FastenerPartNumber

Description Material

AppliedLoad Max

Tensile(lbs)

Max.Comb.Shear(lbs)

Tension S

1 XXXXXXX001

RearFlange

NAS670710 7/1620 UNFX1.3L A286 Fx=125lbs,

Tx=6000inlbs

(LoadCase1)

868 1830 +.36

1SeeNSTS08307,CriteriaForPreloadedBoltsandAnalysis&DesignofFlightVehicleStructures,ChapterD1.8,b

calculations.

1

2

3

45

6

7

8

X

Fastener

Number

C

CS

Y

ExampleFastenerPattern


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REVISION HISTORY

REV DESCRIPTION OF CHANGE DATE APPROVED

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

LYNDON B. JOHNSON SPACE CENTER HOUSTON, TEXAS

TITLE

SCALE: NONE ORG SHEET: X OF X

SIZE CAGE CODE REPORT NO REV

A XXXX -XXXXXX

SIGNATURES DATE

ENG (AUTHOR)

CH (CHECKER)

STRESS (NASA)

APP (APPROVER)

AUTH (NASA)

Figure4:ExampleTitlePageFormatmaybedifferentbasedonoriginatingorganizationstandards

buttitlepageshallcontainrequiredinformationoutlinedinSection4.0


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Figure5:ExampleHandCalculationLocker


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Figure6:ExampleHandCalculationFlap

preparation of stress analysis reports (8594001)

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