composites dalal

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Composite Materials GroupComposites on meso–macro level

Stepan V. Lomov

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Contents

• Research objectives• State-of-the-art 2010• Research perspectives 2011 and beyond

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4

Hierarchy of structural levels in composite materials: nanooP icro

Chowdhury 2007

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Hierarchy of structural levels in composite materials: Picroomeso

Mishnaevsky 2009

Goyal 2008

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Hierarchy of structural levels composite materials: mesooMacrooMEGA

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Composites on meso-Macro level: Research objective

1. Theoretical understanding, experimental study and formalisation into models and design tools of the mechanical behaviour of (nano-engineered) fibrereinforced composites (n)FRC:

• during manufacturing

• in-service performance

2. Optimisation of (n)FRC and development of novel materials with high mechanical properties, toughness and damage tolerance.

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Composites on meso-Macro level: Subject definition

Structural levels: (nano) – micro – meso – Macro

Materials:

1. Fibre reinforced composites (FRC) in general, including nano-engineered (nFRC) with the emphasis on:• Textile composites• Random fibre reinforced composites

2. Heterogeneous materials in general, with forays towards porous and biomaterials

Properties:

1. Internal architecture/structure/geometry, hierarchial organisation

2. Mechanical properties and behaviour, including:• Quasi-static response (elastic properties, non-linearity)• Fatigue• Damage initiation, progression, resistance and tolerance

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Composites on meso-Macro level: Materials of special interest

Cheap and formableRandom fibrecomposites

No delaminationsStructurally stitched

Typical structureMotivationMaterial type

CheapBest realisation of fibre properties

Non-crimp fabrics (NCF)

BeamsEnergy absorption

3D braids

Net shapeNo delaminationsEnergy absorption

3D woven: angle interlock

Best realisation of fibre propertiesNo delaminations

3D woven: non-crimp

Quasi-isotropicCrash resistant

Tri-axial braids

“Guinea pig” for new developments in matrices, fibres, nano-reinforcements …

Woven laminates

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Composites on meso-Macro level: Research philosophy

1. Focus on the material; applications via partnerships.

2. Behaviour of a composite can be understood only if research spans several structural levels.

3. Performance of a composite can be understood only if manufacturing is considered as well.

4. Experimental study should lead to a descriptive, better predictive model.

5. Model development should lead to a numerical tool.

6. Fundamental studies should understand about real behaviour and applications.

7. Applied studies should understand about fundamental phenomena.

11S.V.Lomov - Singapore - May 2010 11

Integrated design tool for textile composites

x

z

p

h z(x)

Q

Q

d2

d1 �Z

A

B

Internal architecture of the reinforcement

Deformation resistance and change of geometry

Compr. Shear Tension Bending

Permeability

M

R=1/K

Drapeability and formability

Impregnation

Production

Mechanical properties and damage

Performance

Structural analysis

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• Research objectives• State-of-the-art 2010

1. Models of textile composites:– WiseTex– Method of inclusions– Integration with PAM-SYSPLY– meso-FE modelling: homogenisation and damage

2. Textile reinforcements:– Internal geometry– Deformability– Permeability

3. Mechanical properties and damage:– Methodology of damage monitoring during test and post-mortem investigation– Fatigue

4. Materials of special interest:– 3D non-crimp woven composites– 3D angle interlock composites– Non-crimp fabrics– Structurally stitched composites– Random fibre reinforced composites

• Research perspectives 2011 and beyond

13S.V.Lomov - Singapore - May 2010 13

WiseTexsoftware package: Virtual textiles and textile composites

• commercialised by K.U.Leuven R&D

• integrated in SYSPLY package of ESI Group

5 industrial licenses

20+ university licenses

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Method of inclusions

G. Huysmans 2 0 0 0 … G. Per ie 2 0 0 9

1C m s s s

m s m sc c c c�ª º ª º � �¬ ¼ ¬ ¼C C C A I A

Eshelby solution

Mori-Tanaka homogenisation

Excellent results for complex textile composites (and random fibre composites)

TexComp

Iso-strain

1515

Integration WiseTex–SYSPLY

WiseTex

Local deformation parameters (thickness, shear…)

Forming: QUIKFORM

Internal geometry

Local stiffness [Q]

FE analysis: SYSPLY

Stress/strain fields

TexComp

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meso-FE: Road map

Geometric modeller

Geometry corrector

Meshing

Assign material properties

Boundary conditions

FE solver, postprocessor

Homogenisation

Damage analysis

N+1 N

N+2

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SACO M ,

ABAQ U S,

AN SYS…

M e sh Te x

W ise Te x

WiseTex–MeshTex/SACOM –commercial FE packages

State-of-the-art numerical tool for preparation of FE models and FE analysis of textile composites on meso-structural level

Geometric modeller

Geometry corrector

Meshing

Assign material properties

Boundary conditions

FE solver, postprocessor

Homogenisation

Damage analysis

Univer sit y of Osaka , Pr of M . Zako

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Damage in textile composites: Standard stiffness degradation schemeStiffness degradation scheme: generally accepted …

real damage: transverse cracks, propagating along braiding yarns … leads to unphysical direction of

propagation of damage: across the fibres inside the yarns

damage zone

D. Ivanov, L. Gor bat ikh 2 0 0 7

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Advanced damage model …

1) Elementary damaged entity: segment

2) Orientation of the failure plane: Mohr-Hashin-Puck concept

3) Degradation scheme

4) Damage evolution law:

5) Combination: micro/plasticity and damage

Crack plane defines the orientation of degradation

¸̧¹·

¨̈©§

crG

Ydd ~

2

Yarn segment: fibre orientation is constant

Damage �l energy release rate

)12(

)11(2

12

122

d

dd ��

�� 2d

12d

22

022 )1( dEE �� )1( 12

01212 dGG ��

)1( 201212 dvv �� )1( 2

02323 dvv �

D. Ivanov, 2 0 0 9

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…brings good predictions (example: 3-axial braid)

experimental damage initiation

Damage development (shear degradation parameter d12) in MD tensile test

Principal levels of applied strain and stress at failure: 1 - damage initiation; 2 –crack density increase (delamination onset); 3 – ultimate failure;

D. Ivanov, 2 0 0 9

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Internal geometry of textile reinforcements: WiseTex

S.V.Lomov, 1 9 9 9 …

x

z

p

h z(x)

Q

Q

d2

d1

�Z

A

B

� � � �min

,,,

� ��

��

� ��

��

� ¦¦�klj

Wejlk

Wejl

Wejlk

Wejlk

Wejlk

kiWaik

Waik

Waik

Waik

Waik

p

hF

p

B

ph

Fp

BW ��

minimum of bending energy + compressibility of yarns

decomposition of the problem + characteristic functions

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Internal geometry of textile reinforcements: Experimental studies

D. Ivanov, 2 0 0 7

Nesting, yarn dimensions and distribution of the fibres

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Materials studied 2000 –2010: internal geometry

Text Res J 72: 706 (2002)Bi- and tri-axial braids

Comp Sci Techn 65: 1920 (2005)3D woven 3Tex

Comp Sci Techn 63: 993 (2002)

Comp Sci Techn 60: 2083 (2000)Plain weaveglass/epoxy

NCF tufted with carbon yarn

Comp A 41: 1301 (2010)3D woven 3Tex

Fibres/matrix Reinforcement Publication

carbon/epoxy NCF 0/90, ±45 Comp A 33: 1171 (2002)

Adv Comp Lett 15: 87 (2006)

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Deformability of textile reinforcements: WiseTexmodels

S.V.Lomov, 2 0 0 1 …

Compression

Uni-and Biaxial tension

Shear

(un)bending + compression of yarnswork of compressive force Q on change of thickness db = change of bending energy of yarns dW

d2Wa

d2We

q

d1Wa

d1We

Qij

TTT

QhWa

p

• Friction between the yarns• Lateral compression of the yarns• (Un) bending of the yarns• Torsion of the yarns• Vertical displacement of the yarns T

T Q

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Deformability of textile reinforcements: Experimental studies

Biaxial tensile tester

0

0.004

0.008

0.012

0.016

0 0.5 1 1.5 2Elong [%]

Forc

e [k

N/m

m]

1:1 2:1

5:1

1:2

1:5

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0 10 20 30 40 50

Shear angle, °

She

ar f

orce

, N/m

m

shear

optical (DIC) registration of the fabric shear

S.V.Lomov, A. W il l ems 2 0 0 4 …

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Shear: Benchmarking exercise

plain weave Twintex

picture frame

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Draping, formability and modelling

FEkinematic

K. Vanc l oost er 2 0 0 8

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Forming diagram for multi-layered preforms

K. Vanc l oost er 2 0 0 9

Formability of multi-layered composites– Depends on the relative orientation between neighbouring plies– Depends on friction between the plies (PP-interlayer thickness)

measurement of interply friction for thermoplastics and FE modelling

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Materials studied 2000 –2010: Deformability

Comp Sci Tech, acceptedTexComp 2010

Twill weave with grafted carbon nanotubes

Comp Sci Techn 65: 1920 (2005)Comp Sci Techn 68: 807 (2008)Comp A 39: 1037 (2008)

Plain weaveTwill

Twintex

J Reinf Plast Comp 19: 1329 (2000)Comp Sci Techn 66: 919 (2006)Text Res J 76: 243 (2006)

Plain weaveglass/epoxy


carbon/epoxy NCF 0/90, ±45, 0/45/-45/90 Comp A 34: 359 (2003)Comp A 36: 1188 (2005)

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Permeability of textile preforms: Simulations

²¢�� ²¢ pgradvP

p = 0

<u>

<u>

p = 'p

A

A´

B. Ver l eye 2 0 0 8

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Permeability of textile preforms: International benchmark

Large scatter of permeability measured in different labs and using different techniques

2nd exercise started 2010

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Materials studied 2000 –2010: Permeability

SAMPE Europe 2003NCF 0/90, +45/-45carbon

Adv Comp Lett 18: 121 (2009)NCF 0/90

Comp A 40: 244 (2009)Stereolithographic reference mediumn/a

Comp A 35: 1407 (2004)Plain weaveglass

Fibres Reinforcement Publication

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3. Mechanical properties and damage:– Methodology of damage monitoring during test and post-mortem

investigation– Fatigue



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Motivation: early damage initiation in textile composites

stress

AE

strain, %No stiffness reduction up to failure

Early damage initiation

Design strain at 0.3 ... 0.4%

Ratio Ultimate strain / Design strain of 4...5

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AE and DIC monitoring of damage

S.V. Lomov 2 0 0 8

objective characterisation of teprogressive damage

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Experimental road map

Textile preparation (shear...), measurements

Impregnation(RTM...)

X-Ray of the unloaded samples

Tension test with AE, strain-mapping

Identification of � 1, � 2, � 3

Tensile tests till � 1, � 2, � 3

C-scan

X-Ray

Cutting according to the crack pattern

Analysis of the cracks on micrographs

Tension diagrams

AE diagrams

Strain maps

Dynamics of damage extent

Damage periodicity

Cracks placement and orientation

Crack length distribution

Damage initiation threshold

Cutting the samples in characteristic directions

Thermal/cure damage characterisation

Architecture of the textile

Fine structure of damage

SEM at the selected positionsMicro-characterisationof damage modes

Study of the reinforcement geometry

S.V. Lomov 2 0 0 8

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Materials studied 2005 –2010: Progressive damage

in writingAutomated tow placement

Comp A submitted3D woven 3Tex

ICCM-17 (2009)Woven twill 2/2


Experimental methodology in general Comp Sci Tech 68: 2340 (2008)

carbon/epoxy NCF 0/90, ±45, 0/-45/90/45 Comp A 36: 1207 (2005)

NCF ±45, sheared Comp A 39: 1380 (2008)

NCF 0/90, ±45, toughened resin Comp A 40: 251 (2009)

NCF tufted with carbon yarn Comp Sci Tech 69: 2701 (2009)

3-axial braid Comp Sci Tech 69: 1373 (2009)

Uniaxial braid Comp Sci Tech 68: 2340 (2008)

Uniaxial weave tufted with carbon Plast Rubb Comp 38: 98 (2009)

3D braided 3Tex ECCM-14 (2010)

glass/epoxy Plain weave Comp A 40: 1134 (2009)Comp A 40: 1144 (2009)3D woven 3Tex

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Tension-tension fatigue: S-N curve and progressive damage

0

50

100

150

200

250

300

350

400

450

500

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07

I

II

III

stress, MPa

number of cycles

time

stre

ss

Vmax

Vmin K. Va l l ons, 2 0 0 7 …

in col l abor a t ion w it h V. Car vel l i, M il ano

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Fatigue limit vs damage initiation threshold

V_min: first AE event

V_1: damage initiation

V_2: initiation of high energy damage events

V_ULT: failure

NCF carbon/epoxy, stitched

NCF carbon/epoxy

NCF carbon/epoxy, unstitched

plain weave glass/epoxy

3D glass/epoxy

carbon/epoxy braid

3D carbon/epoxy

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Materials studied 2007 –2010: Fatigue

NCF tufted with carbon yarn

Comp A submitted3D woven 3Tex

ICCM-17 (2009)Woven twill 2/2


carbon/epoxy NCF 0/90 Comp A 38: 1603 (2007)

NCF 0/90, ±45, toughened resin Comp A 40: 251 (2009)

NCF 0/90 Comp Sci Tech 70: 2216 (2010)

3D braided 3Tex ECCM-14 (2010)

glass/epoxy Plain weave Comp Sci Tech 70: 2216 (2010)

3D woven 3Tex

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3D woven non-crimp composites: Glass/epoxy

in col l abor a t ion w it h A. Bogdanovic h, 3 Tex and V. Car vel l i, M il a no

comparative study: plain weave laminate vs 3D woven composite

3D2D

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3D woven non-crimp composites: Carbon/epoxy

in col l abor a t ion w it h A. Bogdanovic h, 3 Tex, M . Kar ahan, Bur sa and V. Car vel l i, M il ano

detailed study of internal geometry

non-Hookean tensile behaviour

0

100

200

300

400

500

600

700

800

900

1000

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

strain, %

stre

ss, M

Pa

0

10

20

30

40

50

60

70

80

90

100

E, G

Pa

stress, fillE, fill

damage progression and fatigue

AE

S-N

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3D woven non-crimp composites: FE modelling

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• correct modelling of degradation of stiffness

• reasonable evaluation of damage initiation threshold

• qualitative representation of intensity of damage

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3D angle interlock composites

G. Per ie, 2 0 1 0

WiseTex model: excellent predictions of the stiffness

1 m

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3D textiles 1995 –2010

ICCM-17 (2009)Text Res J 81: 1 (2011)

Internal geometryStiffness

3D angle interlock, carbon/epoxy

Comp A, submittedFatigue

Comp A, submittedDamage

Comp A, submittedStiffness, strength

Comp A 41: 1301 (2010)Internal geometry3Tex, carbon/epoxy

Comp Sci Tech, in printFatigue

Comp A 40: 1144 (2009)Damage

Comp A 40: 1134 (2009)Stiffness, strength

Technische Text 38: 20 (1995)Coding of the weaveGeneral 3D weave

Material Properties Publication

3D woven, carbon/epoxy Stiffness Comp Sci Tech 60: 2083 (2000)

3Tex, glass/epoxy Internal geometry Comp Sci Tech 65: 1920 (2005)

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NCF: Internal geometry

S.V. Lomov, 2 0 0 2 ; R. Loender sl oot , 2 0 0 5

Distortions of fibrous plies due to stitching

change of geometry in a sheared fabric

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NCF: Deformability and permeability

Biaxial -45/+45 MD/CD

0

0.004

0.008

0.012

0.016

0.02

0 0.5 1 1.5 2Elong [%]

For

ce [k

N/m

m]

forming

shear (picture frame) and biaxial tension

permeability

S.V. Lomov, 2 0 0 2 , 2 0 0 5

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NCF: Mechanical properties, damage and fatigue

Tr uong, 2 0 0 5 , 2 0 0 8 ; M ikha l uk 2 0 0 8 ; Va l l ons 2 0 0 8 , 2 0 0 9 , 2 0 1 0

MD

Damage initiation and development is linked to the stitching sites

S-N fatigue curves and development of cracks during fatigue

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Structurally stitched reinforcements

Koissin 2 0 0 6 , 2 0 0 9

internal geometry and WiseTexmodel

correlation between damage

and stitching

sites

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A book @ Woodhead Publishers, 2011

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NCF and structurally stitched 2000 –2010

Comp Sci Tech 70: 2216 (2010)Fatigue

Plast Rubb Comp 38: 98 (2008)Comp Sci Tech 69: 2701 (2009)

Mechanical properties, damage, FE damage

Adv Comp Lett 15: 87 (2006)Internal geometryStructurally stitched

Comp A 41: 1019 (2010)Impact and post-impact

Eng Fract Mech 75: 2751 (2008)Comp A 39: 1380 (2008)

FE modelling

Comp A 38: 1633 (2007)Comp A 40: 261 (2009)Comp A 42: 16 (2011)

Fatigue

Comp A 36: 1207 (2005)Comp A 39: 1380 (2008)

Mechanical properties, damage

Comp A 33: 1171 (2002)Comp A 37: 103 (2006)

Internal geometryCarbon/epoxy NCF

Material Properties Publication

Deformability Comp A 34: 359 (2003)Comp A 36: 1188 (2005)

Permeability SAMPE-Europe 2003

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Random fibre reinforced composites

Jao Jul es 2 0 0 5

5%431 2

Successful use of inclusions method for prediction of stiffness and onset of debonding

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1. Integrated Design Tool: – WiseTex: integrations– meso-FE modelling– Fatigue

2. Manufacturing– Compression– Deformability– Permeability

3. Performance– Damage and fatigue

4. 3D composites5. Nano-engineered fibre reinforced composites6. Steel fibre composites

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WiseTex–integrations

Further integration with PAM software

XML input-output and scripting

XML textile data

Custom software

XML description of WiseTex model

in collaboration with

Custom software

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meso-FE modelling: New cases; dry fabrics; numerical tools

Textile composites: New FE models:

• 3K vs 12K carbon/epoxy woven composites

• 3D woven non-crimp composites: exact representation of VF inside yarns and yarn shapes

• Models of NCF: glass/epoxy quasi-UD (wind applications)

Dry fabrics:

• Full implementation of objective strain UMATs

• Implementation of compression model

• Models of shear and biaxial tension

• Models of knitted fabrics

Numerical tools:

• Convertor WiseTex – Meshtex – Abaqus

• Interpenetration tool

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Fatigue modelling: “Fatigue jump” approach

max

�

Applied to:

• Textile composites

• Random fibre composites

59

Compression of nano-grafted carbon fabrics

Compressibility of a fabric after grafting of CNT is seriously decreased

Possible problems in LCM processes

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Deformability: New experimental tools

On-line:

• thickness measurements of thickness of the fabric during shear or tension deformation

• change of yarn width during compression

Direct identification of tension/ compression model of Boisse

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Deformability: Steel knitted fabrics for glass forming

Steel fibres/yarns – Bekaert

Draping of knitted fabric over a glass-forming mould

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Permeability: Second benchmarking exercise

• Decided during FPCM-10 (Ascona, Switzerland)

• Coordinated by EP Montreal

• K.U. Leuven: Geometrical characterisation of the fabrics presented fro the benchmark

• 2010 – 2012

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Damage: carbon woven; Glass NCF; nFRC

Different damage scenario depending on the tow size/ crimp/ …

Shift of the damage initiation in nFRC;

change of mechanism?

Position glass NCFfor wind applications vis-à-vis damage behaviourand fatigue life

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Fatigue: Experimental studies

Relation between the fatigue life and static damage

Reliable input data for fatigue modelling: new experiments and literature data

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3D composites: FE modelling; Voids in C/C composites

FE models with:

• correct VF inside yarns

• correct yarn shapes

• numerical tools for interpenetrations

Inclusion and FE 3D models of C/C composites with voids

Analysis of damage and fatigue experimental data on 3D braids

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Nano-engineered fibre reinforced composite

1. Toughness and damage resistance of nFRC:

• Explanation and theoretical models for the delayed damage in nFRC

• Fatigue damage delay

• Micro-models of damage, including gradient layers in matrix

2. Processing of nFRC:

• Further investigation of compression of CNT-grafted fabrics/yarns

• Permeability of nFRC

3. Macro-damage effects in nFRC

67

Steel fibre reinforced composites

1. Specific effect of plasticity of steel on the composite behaviour

2. Specific effects of the reinforcement architecture (crimp), related to high transversal stiffness of steel

3. Toughness of the interface: gradients of the interface

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