hamid razi: boeing commercial group · list of challenges lack of consistent process for...

11/4/20151

Hamid Razi:Boeing Commercial Group

Background� Justthisyear,theaerospaceindustrywillspendseveralhundredmillion

dollarsonstructuraldesignandcertification

� Fromacademiatoindustry,largeeffortsareunderway(underseveralinitiatives)toadvanceanddevelopProgressiveFailureAnalysis(PFA)methodsandtools toPerformSmartTestingtoDecreaseCostofProduction

� Currentmethodandtooldevelopmentprocessoftendoesnotprovidetheend-usercommunitywithadequateinformationtovalidatemethodsandimplementthemintoproduction.Oftenmethodsprovetobeimpracticaltoimplement.

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CostCheck

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Industries with similar challenges are containing (even reducing) development costs

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ListofChallenges

� Lackofconsistentprocessforverificationandvalidationofprogressivedamageanalysismethods

� Lackofcomprehensivestandardbenchmarkproblemsformethodvalidation.

� Methodtodemonstratescalability(i.e.largermorecomplexstructures)

� MethodcompatibilitywithcommonCAEtoolsets(e.g.,Abaqus)

� Demonstratingmethodapplicabilitytomultiplematerialsystemsanddifferentdesignsandfabricationprocesses

� CompanyProprietarydatarestrictionslimitsharing

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Some But Not All

WhatDoweNeed

� Howdoweverifyandvalidatetheairframewithmoreefficientanalysisandsmarttests?

� Howdowebetterintegratedesignandanalysistoolstominimizechange,errorandrework?

� Howdoweminimizetheuseoflaborintensivetools/methods?

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ValidationApproach� Standard Bench Mark Verifications and Validation Example Depends

on Building Block Approach

Lamina Laminate Element Sub-Structure

Laminate Lamina Element Sub-Structure

•Residual process-induced thermal stress• Manufacturing state of quality• In-situ properties

Test (T., C., S)•Matrix• Fiber • Fracture

Prediction• Soft Layup•Quasi•Hard Layup

Prediction•OH• FH• Impact• Single Stringer

Prediction•Multi-stringer Panel

Test (T., C., S)• Laminate 1• Laminate 2• Laminate 3• Fracture

Determine (T., C., S) •Matrix• Fiber• Fracture

Prediction•OH• FH• Impact• Single Stringer

Prediction•Multi-stringer Panel

Option 1

Option 2

LessonsLearnedfromBottom-UpV&VApproach� Calibratedmodelsatonetierarenotalwaysextendibletonextbuilding-blocktier

� Uppertiersofthebuildingblocktypicallyrichinunknowns

� Falseconfidencegeneratedforpredictingupper-tierresponseleadingtoanunder-estimateofresourcerequirements/priorities.

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PossibleUncertainties

� Fabrication� Fabricationtolerance/variability� Materialpropertiesvariation� Fiber/layerwaviness� Thicknessvariations� Etc

� Test� Failureinitiationmode/mechanism� Damageprogressionmode

� Analysis� Idealization� Boundaryconditions� Inclusionofgeneralizedimperfection� Predictionofdamageinitiationandpropagations� Meshsizes

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Starnes’BottomupV&VImplementationApproach� Unstiffened FlatPanels

� Differentlaminates,knife-edgeBCs,Compression loaded, shearloaded,etc

� StiffenedFlatPanels� Differentstiffenergeometryandspacing, limitedtests,Skin-stringer separation

atbucklenodeline, singlepostbuckling analysisusingbucklingmodesasimperfections, etc

� GapsIdentified� Measuredsurfaceimperfections� Generalizedimperfections� Influence/interactionsofcombined loads� Impactdamagesimulation/modeling

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Boeing Proprietary Information

Typical laminate strain at failure

Adjusted to meet Criteria

Adjusted to B-basis

Adjusted to critical Environment

ε_typ=1

ε_ohc/BVID=0.42

ε_b.ohc=0.371

ε_b.ohc=0.33

Typical Composite Graphite laminateMaterialStrengthandDesignValue

Soccer Ball

Golf ball

Deterministic– Probabilistic� Thebiggestknockdowntodesignstrainiscomingfromdesigncriteria.

� Oftencriteriaareconservativeandresultaddingweightandunnecessarytesting

� Severalthousandin-factoryandin-servicedatahavebeencollectedlast20-30yearswhichcanbeusedtodevelopdesignrequirement

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