Effect of Ply Cracks on Delamination Growth

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Effect of Ply Cracks on Delamination Growth
Jae Noh John Whitcomb Texas AM
University Center for Mechanics of Composites
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Flight Cycle of a Reusable Launch Vehicle

• Severe temperature extremes (from processing
  temperature down to near absolute zero)
• can cause distributed damage in composite gt
  leakage!

Reference S.S. Kessler, T. Matuszeski and H.
McManus. Proceedings of the American Society for
Composites (ASC), 2001.
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Damage Network
Simulation by CFD program, Fluent
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Focal Areas

• Formation of damage
• The leakage path, which includes the opening of
  cracks, the connectivity of the cracks, and the
  uncracked material
• The effective permeability for a given leakage
  path
• Evaluation of current and exploration of new
  nondestructive evaluation techniques

Model to predict microcracking induced
permeability of cryogenic composite tanks
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Predict Microcracking Induced Permeability of
Cryogenic Composite Tanks
Experimental Damage Characterization
Ultrasonic
Analysis of Damage
X-ray
delamination
Simulation of Leakage Path
delamination
Crack opening volume
G, SERR
Load case 1
Load case 2
Load case 3
Whitcomb, Lagoudas, Kinra, Noh
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Computational Modeling

• Fracture mechanics prediction of damage
  formation and growth
• Pop-in of transverse matrix cracks
• Delamination growth near non-intersecting and
  intersecting matrix cracks
• Prediction of opening of damage
• Transverse matrix cracks
• Opening displacements due to delamination at tips
  of TMC
• Single crack
• Intersecting cracks
• Effective permeability of laminates with matrix
  cracks and delaminations

Can laminate design (e.g. stacking sequence)
reduce the formation or the effect of damage?
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Damage Configurations
0
90
0
0
0
0
90
90
0
0
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Delamination at Intersection of TMCs
y
TMC in 0o ply
0o ply
Delamination
90o ply
TMC in 90o ply
x
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Virtual Crack Closure Technique (VCCT)
Delamination front
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FEM Analysis without Contact Constraints
0o
90o
0o
90o
undeformed
deformed
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GI, GII, and GIII for 90/0c/90c/0s
ltexgt 0.5
G (J/m2)
y
s
GIII
GII
x
S
GI
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GI, GII, and GIII for 90/0c/90c/0s
G (J/m2)
ltexgt 0.5
ltexgt lteygt 0.5
GIII
G (J/m2)
GII
S
GIII
lteygt 0.5
G (J/m2)
GII
GIII
GII
S
GI
S
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GI, GII, and GIII for 45/0c/45c/0s
G (J/m2)
ltexgt 0.5
300
y
GII
s
x
GIII
S
G (J/m2)
G (J/m2)
lteygt 0.5
ltexgt lteygt 0.5
300
GIII
GII
GII
GIII
S
S
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Variation of GIII with Delamination Size
GIII (J/m2)
450
R400
100
R200
R100
R
x
100
400
-200
-400
200
-100
0
x
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Variation of GII with Delamination Size
GIII (J/m2)
100
Radius
x
R100
R200
R400
-400
400
-100
-200
100
0
200
x
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Variation of GII and GIII with Delamination
Shape (Circle vs. Ellipse)
y
y
x
x
100
400
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Lack of Interaction Between TMCs
Delamination Radius .5h
Two TMCs
ltexgt 0.5
G (J/m2)
GIII
Two TMCs
One TMC
One TMC
GII
S
GI
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Opening for Different Damage Configurations
( ltexgt 0.5 )
Opening (mm)
two delaminations
one delamination
cd0.5
cd0.1
Normalized delamination length, d/s
(scrack spacing)
Delamination length, d (mm)
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Opening of TMC Delamination
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Comparison of 2D and 3D Configuration
0
s
y
90
100
0
S
x
cd 0.05
3.
2.
Opening (mm)
ltexgt 0.5
1.
delamination length, d or radius (mm)
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Effect of Stacking Sequence on Opening
ltexgt lteygt 0.5, delamination radius 200 mm
2.092
2.272
90/0c/90c/0
1.744
45/0c/45c/0
1.880
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Summary
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Summary
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Computational Modeling

• Prediction of damage formation and growth
• Average strain energy release rate associated
  with pop-in of transverse matrix cracks
• Strain energy release rate for delamination
  growth near non-intersecting and intersecting
  matrix cracks
• Prediction of opening of damage
• Transverse matrix cracks
• Opening displacements due to delamination at tips
  of TMC
• Single crack
• Intersecting cracks
• Effective permeability of laminates with matrix
  cracks and delaminations

Can laminate design (e.g. stacking sequence)
reduce the formation or the effect of damage?
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(No Transcript)
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Laminate with Matrix Cracks and Delaminations
Close-up of single intersection
Laminate with intersecting matrix cracks
Delaminations
Typical FEA model
Various delamination shapes to be considered
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Strain Energy Release Rate for Delamination
Growth Near Intersecting Matrix Cracks
Circle
Ellipse
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FEM Analysis
x
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Warning! Calculation of G
Delta Area
x