Textile composites: from microstructure to mechanical ... · PDF fileTextile composites: from...
Transcript of Textile composites: from microstructure to mechanical ... · PDF fileTextile composites: from...
Textile composites: from microstructure to mechanical properties
Stepan V. LomovDepartment of Materials EngineeringKU Leuven, Belgium
08.09.2016
Contents
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1. Introduction2. Internal geometry of textile composites: WiseTex software3. Micro-CT reconstruction of the fibrous microstructure4. Conclusion
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1. Introduction2. Internal geometry of textile composites: WiseTex software and
around it3. Micro-CT reconstruction of the fibrous microstructure4. Conclusion
Composites in constructions
Windmill blade
Hierarchy of scales: MACRO to meso
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1 km
100 m
10 m
1 m
100 mm
A350 wing
FE model of a composite aeronautic part
Hierarchy of scales: meso to µicro
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100 mm
10 mm
1 mm
100 µm
10 µm
FE: fibre failure
transverse stress in an impregnated yarn
FE model of 3D fabric
Hierarchy of scales: nano to µicro
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Molecular dynamics: interaction CNT -polymer
CNT bending
Carbon nanotubes (CNT) on the surface of a carbon fibre
10 µm
1 µm
100 nm
10 nm
1 nm
Laminates of unidirectional fibre layers
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filament windingBoeing fuselage
Automated fibreplacement (AFP)
Fibrous reinforcements
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Short fibres
• chopped
• non-woven
Long fibres
• tapes (5...500 mm)
• tows (1000 ... 80.000 fibres = 1K … 80K)
• twisted (50...5000 tex)
• commingled (fibres+matrix)
Textile
...
2D textile reinforcements
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Type Structure Fibre orientation in plane
Random fibre mats
Random orientation; fibres can be chopped (short and straight) or continuous (curved)
UD layers Perfectly straight in layers, placed on desired angles
Stitched multi-ply
Almost straight in layers, placed on desired angles; voids formed by stitching
Woven fabrics
Two orthogonal directions (three in triaxial fabrics - rare), slight crimp in z-direction.
Braided fabrics
Two non-orthogonal directions or three if there are inlays, slight crimp in z-direction.
Knitted fabrics
Regular but widely distributed fibre orientation
According to textile manufacturing technology
3D textile reinforcements
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Solid 3D• woven• braided• stitched
Textile sandwiches• woven• knitted
3D shapes• braided• knitted• stitched
Applications and manufacturing
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RTM infusion
autoclave
thermoforming
hand layup
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1. Introduction
2. Internal geometry of textile composites: WiseTex software
3. Micro-CT reconstruction of the fibrous microstructure4. Conclusion
Integrated simulations of textile composites
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x
z
p
h z(x)
Q
Q
d2
d1
Z
A
B
Internal architecture of the reinforcement
Deformation resistance and change of geometry
Compr. Shear Tension Bending
Perme-ability
M
R=1/K
Drapeability and formability
Impregnation
Production
Mechanical properties and damage
Performance
Structural analysis
WiseTex: virtual textile composites
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Internal geometry: textile unit cell
x
z
p
h z(x)
Q
Q
d2
d1
Z
A
B
WiseTex
LamTex
WeftKnit
woven (2D and 3D) braids
weft-knits NCFlaminates
Virtual reality
VRTex
meso-FE
WiseTex -> Ansys
(FETex)
WiseTex -> Abaqus
Composite micromechanics (fast stiffness calculations)
TexComp
Permeability
FlowTex
NX
WiseTex worldwide
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licenses, 2016:
industrial (16)
university (40)
A gallery of WiseTex models
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Data open to the user
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WiseTex or custom software
WiseTex 3.0:
• open XML input and output formats
• “command line” version
New possibilities:
easy integration:
• upstream, with user-defined process models (e.g., braiding process)
• downstream, with user-defined modles of composite (e.g. meso-FE)
XML: textile data
XML: fabricgeometry
custom software
Scripting
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WiseTex 3.0+:
• open XML input and output formats
• “command line” version
New possibilities:
easy integration:
• upstream, with user-defined process models (e.g., braiding process)
• downstream, with user-defined modles of composite (e.g. meso-FE)
scripting:
• parametric studies
• look-up tables (e.g., shear angle)
XML: textile data
XML: fabricgeometry
WiseTex or custom software
custom software
command line script
Multi-level analysis
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WiseTex
Local deformation parameters (thickness, shear…)
Forming
Internal geometry
Local stiffness [Q]
FE analysis
Stress/strain fields
TexComp
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1. Introduction2. Internal geometry of textile composites: WiseTex software
3. Micro-CT reconstruction of the fibrous microstructure
4. ConclusionIlya Straumit
Stepan V. LomovMartine Wevers
Micro computed tomography (micro-CT)
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www.le.ac.uk
Nanotom – GE 0.5 µm
SkyScan, 1 µm
Different textiles
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Modelling workflow
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VoxTex
ABAQUS
FlowTex
Mechanical properties
Voxel (FE) model
Permeability of the composite preform
Stress-strain fields
Structure tensor: Definition
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I – image as three-dimensional function, Ω – image domain, and w(r) – window function.
CT image I
window, defined by w(r)
𝑥1
𝑥3
𝑥2
Structure tensor: Example
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𝑆𝑖𝑗 =16.8 3.6 1.13.6 7.6 0.71.1 0.7 2.8
𝛌 = 𝟐. 𝟕 𝟔. 𝟒 𝟏𝟖. 𝟏
𝑣0 =−0.048−0.1070.993
β = 0.85
Micro-CT image of unidirectional steel fiber reinforced composite.Z is the direction of fibers.
X
Y
Z
Components of the structure tensor:
Eigenvalues:
First eigenvector:
Degree of anisotropy:
Degree of anisotropy
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The ratio of eigenvalues:
𝛽 → 1
𝛽 → 0
anisotropic
isotropic
where 𝜆1 and 𝜆3 are lowest and highest eigenvalues of the structure tensor respectively.
Orientation fields
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Computed orientation fields
isotropic
anisotropic (orientation)
Knitted glass fiber compositeResolution: 4 μm
Segmentation
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grey value – material attenuationstructural anisotropy – material microstructure type
The variables, extracted from the image, reflect physical properties of the material:
Yarns clusterMatrix cluster
Methods of segmentation:• Unsupervised (k-means)• Supervised (Gaussian mixture model)
yarns matrixvoids
Micro-Ct based Abaqus model
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Example: 3D woven composite
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calculated elastic properties
VoxTex software
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Nanotom(3D volume)
VoxTex
ABAQUS
FlowTex
TexComp
Finite element analysis
Permeability
Homogenization (Mori-Tanaka)
ParaView
Visualization
SkyScan,Tomohawk
(image stack)
Root (CERN)
Histograms, statistics
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1. Introduction2. Internal geometry of textile composites: WiseTex software 3. Micro-CT reconstruction of the fibrous microstructure
4. Conclusion
Growing field, steady interest
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0
50
100
150
200
250
300
1980 1990 2000 2010 2020
number of scientific papers on textile composites, per year
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
3.0%
3.5%
4.0%
4.5%
1980 1990 2000 2010 2020
part of “composite + fibre” papers 235,000
links
Composites in the world
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http://compositesmanufacturingmagazine.com/2015/01/what-will-drive-composites-growth-in-2015/
2013
planned for 2014