high performance ductile composites
TRANSCRIPT
![Page 1: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/1.jpg)
Michael R. Wisnom
High Performance
Ductile Composites
Programme Grant
![Page 2: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/2.jpg)
Current high performance composites
Stiff, strong, light, but fail suddenly and catastrophically
![Page 3: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/3.jpg)
HiPerDuCT programme
High Performance Ductile Composites Technology
• Challenge is to create composites that fail more gradually
• Overcome a key limitation of conventional materials: their inherent lack of ductility
• Retain high strength and stiffness
• Potential benefits:
– Increased damage tolerance
– Less notch sensitivity
– Greater work of fracture
– Benign failure
– Warning of overloading
![Page 4: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/4.jpg)
Mechanisms for creating gradual failure
0
200
400
600
800
1000
1200
1400
0 0.5 1 1.5 2 2.5 3 3.5
Strain [%]
Str
ess [
MP
a]
0
200
400
600
800
1000
1200
0.0 0.2 0.4 0.6 0.8 1.0
Strain [%]
Str
es
s [
MP
a]
• Fibre reorientation -using excess length e.g. angle plies
• Strength dispersion e.g. fragmentation in thin ply hybrid laminates
• Aligned discontinuous composites – slip at interfaces
• Ductile fibres
θ
θ’
![Page 5: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/5.jpg)
Mean Max Shear Stress, τ12 = 150 MPa
Mean Shear Modulus, G12 = 2.4 GPa
Mean Failure Axial Strain, εX = 20.3 %
Mean Failure Shear Strain, γ12 = 35 %
Thin Angle Plies – [±45]5S
Skyflex 0.03 mm carbon/epoxy
J. D. Fuller
![Page 6: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/6.jpg)
Thin ±26° laminates
Investigate the influence of resin plasticity using a range of 6 values for n.
β is constant.
3 values of resin modulus, Em:2.5 GPa, 3.5 GPa, 4.5 GPa.
Leads to 18 ‘material’ input files for one-parameter plasticity model.
Each ‘material’ has unique plasticity constants (a66, α and r).
Range of 6 laminate ±θ from ±25° - ±30°in 1° increments.
Vf increased to 50%
εpMeff = β(σM
eff)n
Yields results of size 6x6x3 for each of:
Strength“Yield” StressPseudo-Ductile StrainFailure Strain
“Yield” Point
Pseudo-Ductile Strain
![Page 7: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/7.jpg)
Thin ply hybrid failure modes
Possible failure modes of a ply-by-ply hybrid laminate in tension
Thin ply hybrid behaviour
(multiple cracks+stablelocalised pull-out if any)
Conventional hybrid behaviour 2(single crack+instant unstable delamination)
FF
FF
FF
Conventional hybrid behaviour 1(single crack through the whole thickness)
Low modulus, high strain
High modulus, low strain
Low modulus, high strain
![Page 8: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/8.jpg)
Failure mechanism map
M. Jalavand
![Page 9: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/9.jpg)
0
200
400
600
800
1000
1200
1400
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Strain [%]
Str
es
s [
MP
a]
Stacking sequence: [190GSM S-Glass1/50GSM MR401/190GSM S-Glass1]
High modulus carbon / S-glass hybrid
1.44% pseudo-ductile strain
G. Czel
![Page 10: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/10.jpg)
High modulus / high strength thin carbon/carbon
Lay-up sequence: [28 GSM T10002/50 GSM XN802/28 GSM T10002]
260 GPa modulus0.97% pseudo-ductile strain
![Page 11: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/11.jpg)
Combining mechanisms - [±265/0]S
εd = 2.22%σy = 691 MPa
![Page 12: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/12.jpg)
High Performance Discontinuous Fibres
0
400
800
1200
1600
2000
0 0.4 0.8 1.2 1.6 2S
tress
(M
Pa
)Strain (%)
High performance Carbon/epoxy composites (3 mm of fibre length, 55vf%) E≈115 GPa, σT≈ 1500 MPa
Tape type preform
y
z
xConveyor belt
Fibre suspension jets
Thin parallel plates
Fibre orientation head
50 μm
• Newly developed discontinuous fibre alignment method using water
• Enables high volume fraction and high degree of alignment
• Flexibility to combine different fibre types, lengths…
H. Yu, M. Longana, K.Potter
![Page 13: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/13.jpg)
0
200
400
600
800
1000
0 0.5 1 1.5 2 2.5
Str
ess(
MP
a)
Strain(%)
• HM Carbon/E-Glass epoxy composites
C:G = 1:9
50 µm
C:G = 1:2
50 µm
vf≈55%
Pseudo-ductility obtained from the intermingled-hybrid composites by the fragmentation process in the carbon phase
Carbon ratio
0.10
0.20
0.25
0.33
0.40
0.50
[email protected]@bristol.ac.uk
Intermingled discontinuous hybrids
![Page 14: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/14.jpg)
Conclusions
• A number of approaches to creating more gradual failure demonstrated
• Possible to suppress delamination and cracking using thin plies
• Fibre reorientation in angle plies can create additional strain
• Ply fragmentation in thin hybrids creates a pseudo-ductile response
• Mechanisms can be combined
• Analysis can predict behaviour and produce failure mechanism maps
• Opens up new possibilities for composites which fail more gradually
![Page 15: High Performance Ductile Composites](https://reader031.vdocuments.net/reader031/viewer/2022012420/6174b197f571e576962f8bd7/html5/thumbnails/15.jpg)
Thank you for your attention!
Programme Grant
This work was funded under the EPSRC Programme Grant EP/I02946X/1 onHigh Performance Ductile Composite Technology, a collaboration betweenBristol University and Imperial College, London
Acknowledgement