Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 1
ANALYSIS OF A SHEAR TEST ON A C/C COMPOSITE BY USING
DIGITAL IMAGE CORRELATION AND A DAMAGE MODEL
J.-N. Périé, S. Calloch, C. Cluzel and F. Hild
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 2
Aim: Understanding and modeling the multi-scale behavior
of materials
Model identification (coupons)and validation (mock-ups)
EXPERIMENT / SIMULATIONINTERACTIONS
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 3
Testing machines
Tested objects
Strains obtained by:experiment?computation?
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 4
Material
Model and identification
Shear test
Conclusion
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 5
Some applications of Sepcarb®
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 6
Unidirectional or woven plies
of ex-PAN fibers
(preoxyded)+
Ex-PAN fiber mat
(preoxydised)
Unidirectional or woven plies of HR Carbon
fibers +
Ex-PAN fiber mat
(preoxydised)
Yarns, unidirectional or woven plies
ofcontinuous or
non-continuous HR Carbon
fibers
Preform manufacture (Stacking + Needling)
CarbonizationPyrolysis (>1000°C)
Chemical vapor infiltration
Novoltex® Skinex® Multirex®
Needled laminates [Cavalier]HR Carbon Fibers
HM Carbon Fibers
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 7
Carbon matrix
stacked +“needled”
Layers of continuous fibers “X”
Layers of non-continuous fibers “Y”
and/or
“C/C reinforced laminate”
Carbon preform +
Some preforms …Plane preforms made of non-continuous fibers
NeedlingNeedling
Unidirectional layers
Satin layers
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 8
satin layers
10 mm
Multirex® family
Macro-undulations(scale: n plies)
~1.5 mm~3 mm
unidirectional plies
No-undulation(scale: coupon)
Meso-undulations(scale: ply)
1.5 mm0.5 mm
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 9
Tension/compression tests at 0° and 45° on a [0y,90y]n satin
Non linear for tension test in non-continuous fiber direction Non linear for 45° test
Linear in continuous fiber direction
Multirex® behavior
Str
ess
(MP
a)
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 10
Model for a family of materials
Uniaxial tests
Displacement and strain field measurement
Validation on a set of
composites
Identificationprocedure
Biaxial tests
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 11
Material
Model and identification
Shear on C/C Composites
Conclusion
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 12
Meso-constituents
Layers of continuous fibers
1
2
Layers of non-continuous fibers
1
2
Models
“X”
2 damage parameters: d2 and d12
Transverse tension ≠ compression
“Y”
3 damage parameters: d2 and d12
+ d1 (in fiber direction)
Transverse tension ≠ compressionFiber direction tension ≠ compression
Hybrid laminate
Kinetics of damage:gradual or
brittle (rupture of fibres)
Model designed for a family of materials
Damage meso-model
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 13
y y
E D y 1
2
11
2
E 1 y 0 ( 1 d 1 y
)
11
2
E 1 y 0
22
2
E 2 y 0 ( 1 d 2 )
22
2
E 2 y 0
2
12 y 0
E 1 y 0
11
22
12 2
2 G 12 y 0 ( 1 d 12 )
State: damaged material strain energy
di = piecewise constant (meso level)
mechanism? “crack opening” “crack closure” : positive part of °: initial value of
Mechanisms: friction and incomplete-closure of cracks
Plasticity model with isotropic hardening
Inelasticity
Anisotropic damage theory [Lad 83]
Kinetics:
Associated forces:
“Energy-release rate” Effective stress
Y d i
E
D
d i
˜ d1 ( , , )
d12 or 2 ( , +b )Yd1
Yd12
Yd2
Yd1
Yd12
Yd2
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 14
Elastic parameters: 2 tensile tests on a hybrid [0x,90y]n
Damage kinetics: 2 tensile tests on a [0y,90y]n satin
Elastic longi. and transverse energy
d12(Yd12 ) kinetics
d1(Yd1 ) kinetics
Hyp: d12 and d2 linked
0° tension test
Elastic shear energy
Hyp: no change in d1
45° tension test
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 15
0° tension test on a [0y,90y]n satin
Laminate0y 90y
Loading
d1
d12
d2
Plies
Plastic strains
Stress (MPa)
Test
Simulation
Mean L. Strain (%)Mean T. Strain
(%)
Simulation tool:classical laminate theory
in the non-linear field
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 16
Material
Model and identification
Shear test
Conclusion
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 17
[0y,90y]n C/C Composites
Uniaxial tests
Biaxial tests
Comparison between experiment/simulation
Heterogeneousstrains
Gages Strain fields
CORRELILMT
[Hild, Périé & Coret, 1999]
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 18
Video digital camera + ICPCI bus + PC
Resolution :> 1Mpixels
Coding : 8-12 bits
File format :.bmp,.tiff,
.jpeg…
Interchangeable lenses
Digital camera
Argentic camera or video camera + scanner
Scanning Electron Microscope ...
Tensile machine
CARDAN joint
Long distance microscopeCCD video
camera
PC
C/C specimen
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 19
Principle of image correlation
Displacement
Scale of study:(only depends on magnification and pattern)
t0 t
icro
0.4mm
meso Macro
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 20
Principle of correlation: displacement of 1D signal
x
dd-A d+A
Correlation product: g*f
d
fg g gg
x+Ax
g
Signal
dxgfxgf )()())(*((FFT)
)()()*( gFFTfFFTgfFFT
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 21
Choice of ZOI
Pixel correlation
Extraction of Displaced zone
WindowingFFT correlation + interpolation
Sub-pixel displacement incrementFFT shift of displaced zone
Convergence?
Total displacement
New zone?
Strain computation
Algorithm: CORRELILMTReference image (t0) Deformed image (t)
Reference ZOI Shifted ZOI
V
U
FFT Correlation(precision: pixel)
Max.
Sub-pixel displacement (U,V)
Yes
No
No
Yes
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 22
Shear test on [0y,90y]n C/C Composite (SEPCARB®)
10 mm
Macro-undulation(random distribution)
100 mm
Fibres
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 23
ASTREE: Triaxial testing machine
Image Acquisition
Control
Optical strain field measurement
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 24
Loading (elastic FEA)
Specimen: plate Boundary conditions: displacements
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 25
Validation of geometry:shear damage in a ply
FEA + Damlam [Clu 01]
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 26
Gauges
Artificialspeckle
Surface displacement field
Experimental boundary conditions
x 30
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 27
8-bit signal - Size of ZOI: 64 pixels - ZOI shift: 32 pixels
Practical Precision (strain)~10-4
DIC
Gauge0.2%
Strain (%)
Tim
e (s
)0.2%
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 28
CORRELI2DCORRELI2D
FEAFEA
Displacement fieldStrain field
N°11N°6N°1
Material heterogeneities
?Boundary conditions
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 29
Ply PlyShear damage d12
CORRELI2D
CORRELI2D
Damlam
Strain:
Damage:
CORRELI2D
FEA
Damlam
Strain:
Damage:
Coupling
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 30
Ply Ply
CORRELI2D
FEA
Damlam
Strain:
Damage:
Fiber damage d1
CORRELI2D
CORRELI2D
Damlam
Strain:
Damage:
Coupling
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 31
Brittle failure
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 32
Displacement field measurement (CORRELILMT)
Experimental strain field
(CORRELILMT)
Computation (FEA) of strain field withexperimental
boundaryconditions
Evaluation of damage state: Damlam
??
Brittle failure
Distributed shear damage
(YET THERE ARE DEFECTS)
Onset of fiber damage
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 33
Material
Model and identification
Shear on C/C Composites
Conclusion
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 34
Meso model
Specific identification procedure
1 stacking sequence2 meso constituents
Model implemented in Damlam
Mock-up design
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 35
Experiment / Simulation coupling
Displacement field measurement
Multiaxial experiment (mock-up)
Experiment interpretation by using the material model
Applications of Optical Techniques
Analysis of a shear test on a C/C composite by using digital image correlation and a damage model 36
Understanding and modeling the multi-scale behaviorof (composite) materials
Measurement of fields (DIC)
(texture = tracer)
Numericalsimulations
Control oftest
Real-time simulation
Multi-scalemeasurement
Resolution of CCD cameras
Inverse identification