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5/28/2018 Stress Analysis Report NASA
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- AS RELEASED 12/22/2009
REVISION HISTORY
REV DESCRIPTION OF CHANGE DATE APPROVED
NATIONAL AERONAUTICS AND SPACE ADMINISTRATIO
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 RE
A 2135 -8594001
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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
analystshall
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)
Welded
joint
analysis
f) Bonding,adhesive,andfrictionanalysisg) Linearandnonlinearresidualstressanalysish) Tolerance,interference,mismatch,thermalandotherstructuralanalysis
4.0 ReportFormatThestressanalysisreportshallcontainthesectionsshowninFigure1.Allsectionsshallbeclearly
labeledandallreportpagesnumbered.Anexplanationofthecontentofthesesectionsfollows.
Figure1:StressReportOutline
TITLEPAGETABLEOFCONTENTSLISTOFSYMBOLSANDACRONYMS
1.0EXECUTIVESUMMARY2.0MINIMUMMARGINOFSAFETYSUMMARYTABLE3.0 INTRODUCTION4.0MATERIALPROPERTIES&ALLOWABLESSUMMARY5.0COORDINATESYSTEMS6.0LOADSSUMMARY7.0CALCULATIONS8.0REFERENCES9.0APPENDIX
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TITLEPAGEThetitlepageofthereportshallincludeareportnumberandtitle.Itshallbespecific,unique,and
concise.Acronymsshallnotbeusedinthetitlewithoutdefinition.Thetitlepageshallincludearevision
blockforreportrevisions.AnexampletitlepageisshowninFigure4.
TABLEOFCONTENTSAtableofcontentsshallbeincludedinthereportlistingeachreportsectionandapplicablepage
number.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
shall
be
included:
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)
Every
equation
shall
be
referenced
to
its
source
by
section/page
number
and
the
source
listed
in
thereferencesectionofthereport.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 MinimumMar
ofSafetyPartNumber Name Material FailureTheory AppliedLoad
(LoadCase) Yld.1 U
MSCZZD001001 Widget Ti6AL4V VonMises Fx=125lbs,
Tx=6000inlbs
(LoadCase1)
+.05 +
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 MaximumNormalStre Buckling Fatigue TsaiWu Other(describe)
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Figure3:FastenerMinimumMarginofSafetySummaryTablFastener Analysis FastenerForces Minimu
# FastenerLocation
FastenerPartNumber
Description Material
AppliedLoad Max
Tensile(lbs)
Max.Comb.Shear(lbs)
Tension
1 XXXXXXX001
RearFlange
NAS670710 7/1620 UNFX1.3L A286 Fx=125lbs,
Tx=6000inlbs
(LoadCase1)
868 1830 +.36
1SeeNSTS08307,CriteriaForPreloadedBoltsandAnalysis&DesignofFlightVehicleStructures,ChapterD1.8
calculations.
1
2
3
45
6
7
8
X
Faste
Numb
Y
ExampleFastenerPattern
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REVISION HISTORY
REV DESCRIPTION OF CHANGE DATE APPROVED
NATIONAL AERONAUTICS AND SPACE ADMINISTRATIO
LYNDON B. JOHNSON SPACE CENTER HOUSTON, TEXAS
TITLE
SCALE: NONE ORG SHEET: X OF X
SIZE CAGE CODE REPORT NO RE
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