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downloaded from: http://www.mtm.kuleuven.ac.be/Research/C2/poly/index.htm 1
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
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A gallery
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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
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1. Introduction: Experimental and modelling methods for studying progressive damage
2. Woven composite
3. Non-crimp fabric composite
4. Structurally stitched composite
5. Conclusions
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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)
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Test methods: tension-tension fatigue
Load-controlled (MTS, Schenk)
R = 0.1
f = 6…10 Hz
time
stre
ss
Vmax
Vmin
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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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Damage model in FEA
Damage initiation: Hoffmann
29
28
27654
23
22
21 )()()(
LTZLTZZTL
TLLZZT
CCCCCC
CCCF
WWWVVV
VVVVVV
�����������
°°°°°°°°
¿
°°°°°°°°
¾
½
¸̧¹·
¨̈©§ ¸̧¹
·¨̈©§ ¸̧¹
·¨̈©§
� � �
¸̧¹·
¨̈©§ ��
¸̧¹·
¨̈©§ ��
¸̧¹·
¨̈©§ ��
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
FFFFFFC
Definition of the damage mode
L T
Z
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1. Introduction: Experimental and modelling methods for studying progressive damage
2. Woven composite
• Static tension
• Finite element analysis
3. Non-crimp fabric composite
4. Structurally stitched composite
5. Conclusions
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Woven carbon/epoxy composite
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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
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FE modelling: Material properties and mesh
fine mesh:
26,639 elements
coarse mesh:
5375 elements
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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
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1. Introduction: Experimental and modelling methods for studying progressive damage
2. Woven composite
3. Non-crimp fabric composite
• Tension
• Tension-tension fatigue
• Finite element analysis
4. Structurally stitched composite
5. Conclusions
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Non-crimp fabric carbon/epoxy composite
loading direction
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NCF, Tension
(+45/-45, +45/-45)s
Loading in fibre direction
Damage initiation at strain 0.3%
Saturation of the system of transversal cracks
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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
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Damage development in fatigue, load 250 MPa500,000 1,000,000 5,000,000
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Damage saturation in fatigue
Load: 250 MPa
(damage initiation level)
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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
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1. Introduction: Experimental and modelling methods for studying progressive damage
2. Woven composite
3. Non-crimp fabric composite
4. Structurally stitched composite
• Tension
• Tension-tension fatigue
5. Conclusions
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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
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Tension: stitched VS non-stitched
Change after stitching
stitched
non-stitched
AE energy
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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
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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
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1. Introduction: Experimental and modelling methods for studying progressive damage
2. Woven composite
3. Non-crimp fabric composite
4. Structurally stitched composite
5. Conclusions
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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.