Damage initiation and development in textile composites: A ... › onderzoek › scalint › ... · 1,E+00 1,E+01 1,E+02 1,E+03 1,E+04 1,E+05 1,E+06 1,E+07 1,E+08 Number of cycles

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Damage initiation and development in textile composites: A galleryStepan V. LOMOV, Dmitry S. Ivanov, Vitaly KOISSIN, Jan KUSTERMANS,

Katleen VALLONS, Jian XU, Ignaas VERPOEST

Department MTM, Katholieke Universiteit Leuven, Belgium

Valter CARVELLI, Vanni Neri TOMASELLI

Politecnico di Milano, Italy

Björn VAN DEN BROUCKE

EADS Innovation Works, Munich, Germany

Volker WITZEL

IFB - Institut für Flugzeugbau, Universität Stuttgart, Germany


A gallery


Contents

1. Introduction: Experimental and modelling methods for studying progressive damage

2. Woven composite

3. Non-crimp fabric composite

4. Structurally stitched composite

5. Conclusions



2. Woven composite



5. Conclusions


Test method: quasi static tension

2D-24

0

100

200

300

400

500

0 0.5 1 1.5 2 2.5 3 3.5strain, %

stre

ss, M

Pa

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

AE

stress-strainAE eventsAE cumulative

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

0 0.2 0.4 0.6 0.8 1

strain, %

AE

ene

rgy

cumulativeenergyenergy ofevents

0.E+00

5.E+03

1.E+04

0 0.2 0.4 0.6 0.8 1strain, %

AE

ene

rgy

0.E+00

5.E+07

1.E+08

0 0.2 0.4 0.6 0.8 1strain, %

AE

ene

rgy

H1

H2

a

b

c

Hmin

H1

H2

Displacement-controlled tension (Instron)

Acoustic emission (Vallen)

Strain-mapping (LIMESS)


Test methods: tension-tension fatigue

Load-controlled (MTS, Schenk)

R = 0.1

f = 6…10 Hz

time

stre

ss

Vmax

Vmin


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


Damage model in FEA

Damage initiation: Hoffmann

29

28

27654

23

22

21 )()()(

LTZLTZZTL

TLLZZT

CCCCCC

CCCF

WWWVVV

VVVVVV

��

°°°°°°°°

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°°°°°°°°

¾

½

¸̧¹·

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·¨̈©§ ¸̧¹

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� � �

¸̧¹·

¨̈©§ ��

¸̧¹·

¨̈©§ ��

¸̧¹·

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2

9

2

8

2

7

654

3

2

1

1,

1,

1

11,

11,

11

11121

11121

11121

sLT

sZL

sTZ

cZ

tZ

cT

tT

cL

tL

cZ

tZ

cT

tT

cL

tL

cT

tT

cL

tL

cZ

tZ

cL

tL

cZ

tZ

cT

tT

FC

FC

FC

FFC

FFC

FFC

FFFFFFC

FFFFFFC

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Definition of the damage mode

L T

Z



2. Woven composite

• Static tension

• Finite element analysis



5. Conclusions


Woven carbon/epoxy composite


Tension

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0 0.005 0.01 0.015

average strain

loca

l stra

in

point #1

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0 0.005 0.01 0.015

average strain

loca

l stra

in

eps_X at applied strain 1%

point #5


FE modelling: Material properties and mesh

fine mesh:

26,639 elements

coarse mesh:

5375 elements


FE modelling: results

0

200

400

0.0 0.5 1.0strain, %

stre

ss, M

Pa

experimentf ine meshrough meshrough mesh stif feningfine mesh stif fening

eps_T,

strain 0.29%

damaged elements

0.29% 0. 52%

0.290.24 r 0.05H_1, %

0.070.08 r 0.03Q43.642.9 r 3.8E, GPa

FEA, fine mesh

Experiment



2. Woven composite


• Tension

• Tension-tension fatigue

• Finite element analysis


5. Conclusions


Non-crimp fabric carbon/epoxy composite

loading direction


NCF, Tension

(+45/-45, +45/-45)s

Loading in fibre direction

Damage initiation at strain 0.3%

Saturation of the system of transversal cracks


NCF, tension-tension fatigue

0

200

400

600

800

1000

1,E+00 1,E+01 1,E+02 1,E+03 1,E+04 1,E+05 1,E+06 1,E+07 1,E+08

Number of cycles to failure

Max

stre

ss (M

Pa)

BD+ BD-

Damage initiation stress level in static tests in BD+

Damage initiation stress level in static tests in BD-

MD

BD+

BD -

CD

V1

V 1

V _ult

Fatigue limit is HIGHER than the damage initiation threshold


Damage development in fatigue, load 250 MPa500,000 1,000,000 5,000,000


Damage saturation in fatigue

Load: 250 MPa

(damage initiation level)


NCF, finite element analysis

mesh in the plies

fibre orientations near an opening

change of Young module

Puck’s stress intensity factor at the damage initiation level



2. Woven composite



• Tension

• Tension-tension fatigue

5. Conclusions


Structurally stitched NCF carbon/epoxy composite

54045°/-45°

5560°/90°

areal density, g/sq. m

5 mm63VF, %

3.2plate thickness, mm

15twist, 1/m

67linear density, tex

carbon 1K

stitching


Tension: stitched VS non-stitched

Change after stitching

stitched

non-stitched

AE energy


Tension: damage patterns

non-stitched

stitched

strain 0.3%strain map (eps_X) on the surface of the tufted composite

structural stitching

PES stitching on NCF


Tension-tension fatigue

0

100

200

300

400

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

Failure Cycles

Str

ess

[MPa

]

Unst it ched 0º Unst it ched 90º

V 1

0

100

200

300

400

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

Failure Cycles

Str

ess

[MPa

]

St itched 0º St it ched 90º

V 1

non-stitched

stitched

Fatigue limit is HIGHER than the damage initiation threshold



2. Woven composite



5. Conclusions


Conclusions

1. The methodology of studying damage processes in textile composites, has been successfully applied to different materials in conjunction with fatigue testing and FE modelling.

2. Clear relation is identified between the damage initiation limit in static tests and fatigue life limit, as well as analogy between the progressive damage patterns for static tests (increasing strain) and fatigue (loading cycles).

3. Meso-FE modelling proved to be able to produce adequate description of damage processes in textile composites.

Damage initiation and development in textile composites: A ... › onderzoek › scalint › ... · 1,E+00 1,E+01 1,E+02 1,E+03 1,E+04 1,E+05 1,E+06 1,E+07 1,E+08 Number of cycles

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