FEM Impact Simulation: Fan Blade Out Event for a Composite Fan Containment Case

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FEM Impact Simulation: Fan Blade Out Event for a Composite Fan Containment Case

FEM Impact Simulation: Fan Blade Out Event for a Composite Fan Containment Case

Dr. Clara Schuecker, Dr. Mathias Luxner, Dr. Clara Schuecker, Dr. Mathias Luxner, Dr. Martin Fleischmann, DI(FH) Jürgen TauchnerDr. Martin Fleischmann, DI(FH) Jürgen Tauchner

2014 European Altair Technology Conference (EATC)2014 European Altair Technology Conference (EATC)

June 26, 2014June 26, 2014 2014 European Altair Technology Conference (EATC)2014 European Altair Technology Conference (EATC) 22

Luxner Engineering ZT GmbHLuxner Engineering ZT GmbH

Engineering consulting firm

Organisation

Founder & Owner: DI Dr.techn. Mathias H. Luxner

Locations: Imst & Vienna, Austria

Expertise

Finite Element Analysis

Lightweight design & composite materials

Methods development

Software implementations

Focus: Research and Development

„Bringing Science and Engineering together“

Imst

Wien


DefenCE ProjectDefenCE Project

3 Year Research ProjctFunded by FFG – Austrian Research Promotion Agency

3 Project Partners FACC AG

Luxner Engineering ZT GmbH

Vienna University of TechnologyInstitute of Light Weight Design and Structural Biomechanics

Goals: develop composite fan containment case

reliable analysis methods for composite impact simulation

Fan-Blade Off (FBO)


FBO – problem definitionFBO – problem definition

Geometry Material Parameters Boundary conditions Load application

Mounting

Composite casing

Titanum blade

Rotation Contact


Results FBO analysisResults FBO analysis


Different results FBO analysisDifferent results FBO analysis


??

so which one is correct?

So which one's realistic?


Analysis ingredientsAnalysis ingredients

Blade material damage degradation

Casing material(s) damage degradation, element deletion

...for each direction

failure criteria

Property formulation hourglassing, shell formulation, …

Contact formulation gap definition, penalty stiffness, …

Modeling approach UD-analogy, Solid vs Shell, CZE, ADM, …

Mesh refinement

numerical parameters physical parameters


Simplified test problemSimplified test problem

Standard droptower testISO 6603-2, ASTM 3763

impactor adjusted to blade-like geometry


Mesh density effectMesh density effect

coarse(3750 el)

fine(15000 el)

extra fine(60000 el)


Sources of mesh density effectSources of mesh density effect

resolution of stress distribution(geometry / contact)

→ convergence

damage material law

softening leads to localization(ill-posed problem)

no convergence →(without regularization) localization

in 1 element row


Damage mechanics and localizationDamage mechanics and localization

fracture mechanics: dissipation related to crack formation energy release rate („toughness“)→… energy dissipated per cracked area

damage mechanics: homogenized material law… energy dissipated per volume element

micro cracking

crackpropagation

fullycracked

fracture

damage

homogenizeddamage

law


Softening with characteristic lengthSoftening with characteristic length

Bažant crack band model[Materials and Structures 16, pp.155-177, 1983]

adjusted material law /Mat/Law25

with

...area associated with integration point

...constant dependent on element type

...characteristic length

for quadratic elements (reduced integration):

general formulation brittle material

requirement for minimum element size:


Results including characteristic lengthResults including characteristic length

adjusted damage law gives (almost) mesh independent result

coarse(3750 el)

fine(7500 el)


Conclusions – mesh size dependencyConclusions – mesh size dependency

issue of mesh size dependency has beed identified adjustment with characteristic length gives objective results for full scale analysis an automated solution is required

(mesh size & mesh type dependent ) varying mesh sizes→ adaptive meshing→

εm = f (Gc, Lch)e.g. /Fail/user


mesh pattern dependencymesh pattern dependency

cracks tend to follow mesh pattern

→ aligned mesh if crack direction is known a-priori

→ random mesh to allow for realistic crack pattern

Consistent (~15.000 elem) Locally refined (~17.000 elem) Random (~19.000 elements)

t=0.6ms

t=0.9ms

t=0.6ms

t=0.9ms

t=0.6ms

t=0.9ms


modeling strategiesmodeling strategies

solids / shells Composite model

UD-analogy

CZE / delamination

adaptive meshing X-FEM


sensitivity analysessensitivity analyses

sensitivity analyses: element formulation / deletion options

number of thickness integration points

interface formulations

IOFF=4 IOFF=5 IOFF=6

Note: dissipated energy shown for fabric material modeleffect much more pronounced for UD-material!


Further workFurther work

quantitative evaluation of modeling approaches

→ determine which mechanisms need to be captured for reliable prediction

→ determine how these mechanisms can be modeled efficiently on a structural level

verification by experiments material tests

small scale tests

full scale prototype test

development of feasable analysis strategies for full scale simulation