The Mechanical Performance of Laminated
Structures – A Simulation Concept
Integrating Ply and Interface Non-Linearities
H.E. Pettermann, J. Gager,
Th. Flatscher, E. Rama Lista
Inst. of Lightweight Design and Structural Biomechanics
Vienna University of Technology, Austria
Polymer Competence Center Leoben, Leoben, Austria
FACC Technical Colloquium, 5-6 July 2012
1
Selected references
Th. Flatscher and H.E. Pettermann.
A constitutive model for fiber-reinforced polymer plies accounting for plasticity and brittle damage including
softening - implementation for implicit FEM.
Composite Structures, 93(9):2241–2249, 2011.
Th. Flatscher, C. Schuecker, and H.E. Pettermann.
Prediction of plastic strain accumulation in continuous fiber reinforced laminates by a constitutive ply
model.
International Journal of Fracture, 158:145–156, 2009.
Th. Flatscher, M. Wolfahrt, G. Pinter, and H.E. Pettermann.
Simulations and experiments of open hole tension tests — assessment of intra-ply plasticity, damage, and
localization.
Composites Science and Technology, 72(10):1090–1095, 2012.
J. Gager and H.E. Pettermann.
Numerical homogenization of textile composites based on shell element discretization.
Composites Science and Technology, 72(7):806 – 812, 2012.
C. Schuecker and H.E. Pettermann.
Constitutive ply damage modeling, FEM implementation, and analyses of laminated structures.
Computers & Structures, 86(9):908–918, 2008.
G. Wimmer, W. Kitzmüller, G. Pinter, T. Wettemann, and H.E. Pettermann.
Computational and experimental investigation of delamination in l-shaped laminated composite
components.
Engineering Fracture Mechanics, 76(18):2810 – 2820, 2009.
Outline
1
Aims & Scope
2
Approach
shell modeling concept
non-linear ply behavior
interface modeling
3
Applications
open hole tension test
braidings/weaves
3 point bending
L-flange
4
Conclusion
3
Outline
1
Aims & Scope
2
Approach
shell modeling concept
non-linear ply behavior
interface modeling
3
Applications
open hole tension test
braidings/weaves
3 point bending
L-flange
4
Conclusion
4
Aim
Aim
predict non-linear behavior of laminated structures
• beyond elastic limit
• peak load predictions
• failure modes
• progression of damage in
plies and interfaces
ply damage induced
delamination
delamination induced
ply damage
[Schuecker, PhD-Thesis]
5
Aim
Computational efficiency
in terms of
• computation time
• hardware requirements
academic
state-of-the-art
aspired
6
Outline
1
Aims & Scope
2
Approach
shell modeling concept
non-linear ply behavior
interface modeling
3
Applications
open hole tension test
braidings/weaves
3 point bending
L-flange
4
Conclusion
7
Length Scales
hierarchical length scales of laminated FRP
8
Shell Modelling Concept
Common approach – layered shell
9
Shell Modelling Concept
Multiple shell approach
FEM model of a
composite structure
constitutive model for
"smeared out"
ply material
multiple shell elements
with interfaces
degradable interfaces
10
Ply Behavior
ply material behavior — brittle vs. ductile
→ ductile behavior — accumulation of residual strains
→ brittle behavior — stiffness degradation (but hardening)
→ brittle behavior — softening (localization)
11
Ply Behavior
• plasticity model
• distributed damage model
• localized damage model
[Flatscher/Schuecker/Pettermann 2009]
12
Ply Behavior
• plasticity model
• distributed damage model
• localized damage model
[Schuecker/Pettermann 2008]
12
Ply Behavior
• plasticity model
• distributed damage model
• localized damage model
[Flatscher/Pettermann 2011]
12
Ply Behavior
advantage of the model
• anisotropic damage
• modeled mechanisms determine the response
• interpretable parameters
• no introduction of sites where failure is expected
FE-software model (Abaqus)
• anisotropic localized damage
• numerically efficient
• no plasticity
• no distributed damage
13
Interface modeling
Interface modeling
cohesive contact / cohesive elements
• degradable interface properties
• no existing cracks necessary
• readily available
14
Outline
1
Aims & Scope
2
Approach
shell modeling concept
non-linear ply behavior
interface modeling
3
Applications
open hole tension test
braidings/weaves
3 point bending
L-flange
4
Conclusion
15
OHT — Experiments vs. Simulations
fiber reinforced epoxy UD
[(+45/− 45)4 ]S
focus on ply non-linearities
no inter-ply delamination
X-SYMM
curing stresses are taken into account
Y-SYMM
16
Experimental Setup at PCCL
[Flatscher, et.al 2012]
MTS, ARAMIS
specimen production at FACC AG
17
OHT — Experiments vs. Simulations
[(+45/− 45)4 ]S — longitudinal strains εxx ; same scaling
Experiment: F = 10.6 kN (top)
Simulation: F = 9.8 kN (bottom)
18
OHT — Experiments vs. Simulations
[(+45/− 45)4 ]S — localization
19
Braidings / Weaves
hierarchical length scales of textile laminates
macro
(structure)
meso 2
(lamina)
meso 1
(textile ply)
micro
(fiber)
20
Braidings / Weaves
Uniaxial tensile loading
21
Braidings / Weaves
Multilayer Laminates
22
3 Point Bending
0/90 two layer laminate
each layer – shell elements
cohesive zone for delamination
u
0
90
5
depth: 0.03
2x
0.175
CZ
U
23
3 Point Bending
damaged transverse Young’s modulus E2
damage induced delamination
L-Flange
lay-up [0/90/0/90/0]S
based on PhD thesis G.Wimmer → focus on delamination
Experiments at PCCL, samples by FACC AG
[Wimmer,2008]
25
L-Flange
ply damage relevant stress state at the delamination front
(not yet critical)
L-Flange
progressive delamination ⇒ ply stresses reach critical value
delamination jumps to next interface
delamination induced ply damage
L-Flange
[Wimmer,2009]
28
Outline
1
Aims & Scope
2
Approach
shell modeling concept
non-linear ply behavior
interface modeling
3
Applications
open hole tension test
braidings/weaves
3 point bending
L-flange
4
Conclusion
29
Conclusion
simulation of laminated structures based on. . .
• anisotropic ply damage — including softening
• ply plasticity
• delamination
ply damage – delamination interaction
... tools for highly non-linear structural analyses
30
The Mechanical Performance of Laminated
Structures – A Simulation Concept
Integrating Ply and Interface Non-Linearities
H.E. Pettermann, J. Gager,
Th. Flatscher, E. Rama Lista
Inst. of Lightweight Design and Structural Biomechanics
Vienna University of Technology, Austria
Polymer Competence Center Leoben, Leoben, Austria
FACC Technical Colloquium, 5-6 July 2012
31