Composites for Future Aircraft

berlinpotatoMechanics

Nov 18, 2013 (3 years and 9 months ago)

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Recent Developments in
Composites for Future Aircraft

Professor Adrian Mouritz FIEAust

2

Aerospace Composites


Aerospace industry has undergone a „silent
revolution‟ over past 10
-
15 years with
composites.


Composite technology infiltrated every type of air
platform.


Design, fabrication & in
-
service maintenance of
aircraft changed radically with composites.


Many factors behind use of composites:



fuel cost



environment (greenhouse gases)



maintenance (corrosion, fatigue)



airframe life extension



….


3

3

Aerospace Composites


Presentation format:



Short history



Types of composites



New developments



self
-
healing composites



nanoparticle composites



multi
-
directional fibre composites



structural health monitoring


This presentation is largely my view & RMIT
biased!


Presentation does not consider everything:


-

manufacturing


-

certification


-

repair etc.





3

4

Short history of aerospace materials

Introduction of composites result of growing engineering,
economic and environmental requirements on aircraft.


5

Short history of aerospace materials

Many structural materials have been used to meet the challenges.


6

Composites: The “good story”

Advantages of using composites include:



Light
-
weight (fuel saving, pollution)


High stiffness, strength & fatigue life


Corrosion resistant


Integrated structures


Radar absorbing properties


Acoustic transparency


Vibration damping (sometimes)




laminate

sandwich
composite

fibre metal
laminate

7

JSF (2007): 35%

F
-
18C/D (~1990): 15%

F
-
15 (1975): 4%

1960
1970
1980
1990
2000
2010
2020
0
10
20
30
40
50
60
B-2
V-22
Eurofighter
Rafale
F22
F35
AV8B
F18E/F
Mirage 2000
Torando
F16
F14
Weight Percent of Composite
Year of Introduction into Service
military fighters
Aerospace Composites

8

8

B787 (2010): 50%

B777 (1995): 10%

B747 (1970): 3%

1960
1970
1980
1990
2000
2010
2020
0
10
20
30
40
50
60
B-2
V-22
Eurofighter
A400M
B787
A350
A380
A320
MD90
B777
A330
A340
MD11
A321
B757
A310
B767
MD80
A300
B747
B737
Rafale
F22
F35
AV8B
F18E/F
Mirage 2000
Torando
F16
F14
Weight Percent of Composite
Year of Introduction into Service
military fighters
civilian airliners
Aerospace Composites

9

Boeing 787 Dreamliner

10

Airbus A380

11

Aerospace Composites


Rise of composites leading to demise of aluminium.


What the future holds for aluminium ????


12

Composites: The “not so good story”

Disadvantages of using composites include:



Cost


Impact damage resistance


Post
-
impact mechanical properties


High strength joining


Lightning protection


Fire resistance & flammability


Recycling

13

Self
-
Healing & Biomimetic Composites

14

Self
-
Healing Composites




Composites susceptible to delamination
and matrix cracking from:

o

service
-
induced (over
-
loading) stresses

o

edge stresses

o

environmental degradation

o

foreign object impact damage


Self
-
healing a possible solution?


15

Conventional repair methods for
delamination

o

removal of damaged material

o

mechanically fastened repairs

o

adhesive bonded repairs


These repairs are expensive, complex,
time
-
consuming.


Current damage tolerant design for
aircraft incorporates large safety margins
for repairs which lead to overweight &
inefficient composite structures
structures.

Self
-
Healing Composites

16

Self
-
Healing Composites


One promising repair approach is

self
-
healing technology
” based on
the healing processes of plants &
animals.




Capacity to partially or completely heal
delamination and matrix cracking.



Restore mechanical properties of
damaged composite.



Self
-
healing technology comprises


microcapsules


microvascular fibres


mendable polymers

healing of human skin

17

17

Microcapsule self
-
healing

Moore, White, Sottos


University of Illinois

18

Microvasculate

self
-
healing

microvascular composite

19

Mendable polymer composites

Various types of mendable polymers for self
-
healing composites:



reversible Diels
-
Alder bonding



stress
-
induced cross
-
linking



thermoplastic solid solutions

20

Mendable polymer composites

Before healing

After healing



From
Meure et al.

RMIT & CSIRO investigating thermoplastic additives to heal
cracks in damaged aerospace composites.


epoxy phase


EMAA


EMAA


21

0
1
2
3
4
5
0.0
0.5
1.0
1.5
2.0
Mode I Interlaminar Fracture Toughness (kJ/m
2
)
Number of Healing Cycles
No EMAA (control)
4 ply/50
m EMAA
4 ply/100
m EMAA
Mendable polymer composites

Self
-
healing with thermoplastic can be performed multiple times



not just once like many other self
-
healing methods

22

Biomimetic composites

Biomimetic composites for light
-
weight
aerospace structures with improved
mechanical performance & damage tolerance.



High toughness materials
e.g. shell, bone



High strength materials
e.g. spider silk



High performance structures
e.g. tree
joints



23

Biomimetic composites


Biological design & adaptations of tree
branch joints to increase structural
properties of composite joints.


Tree joints have many properties highly
desirable in aerospace composite joints.



increased failure stress (40%
improvement)



increased fracture toughness & damage
resistance (50% improvement)



suppression of brittle fracture


improved impact resistance


Property improvements amongst the
highest ever achieved for bonded
composite joints.

24


Optimised design of skeletal structures for
maximum strength and minimum weight
for core materials in composite structures.


Mimic cellular structure of high strength,
low density bones to replicate core
materials.


Analysis and testing of new design
concepts for skeletal materials for
advanced composite structures.

Biomimetic composites

25

Damage Resistant Composites

26

Damage tolerant composites

New types of composites developed for
damage resistance (bird strike
etc
).


3D woven composites


Stitched composites


Z
-
pinned composites


Nanoparticle composites



What the future holds is still unclear.



27


Reduced manufacturing cost & time


Improved delamination resistance (0.4


4 kJ/m
2
)


Increased joint strength (more than 100%)


Restricted to dry fabrics; not prepregs

3D woven composites

28


Reduced manufacturing cost & time


Improved delamination resistance (0.4


8 kJ/m
2
)


Increased joint strength (by ~25%)


Restricted to dry fabrics; not prepregs

Stitched composites

29

Z
-
pinned composites


Z
-
pins are thin rods inserted
through
-
the
-
thickness of laminates &
sandwich composites.



Z
-
pins made of high stiffness &
strength material:


carbon fibre rods


titanium rods


….



Z
-
pins used in improve
interlaminar

properties:


delamination resistance


impact damage resistance


bonded joints





30

Composite

G
Ic

(J/m
2
)

Increase

No pins

970 (

90)

-

0.5%

z
-
pins (thin)

2700 (

290)

2.8 x

2.0% z
-
pins (thin)

15025 (

1428)

15.5 x

4.0% z
-
pins (thin)**

14680 (

1590)

15.1x

Large increase in delamination fracture toughness


Z
-
pinned composites

31

Z
-
pinned composites

Large increase in delamination fatigue resistance by z
-
pinning


0.1
1
10
10
-8
10
-7
10
-6
1x10
-5
1x10
-4
10
-3
10
-2
10
-1
10
0
10
1
290
m z-pin diameter
Delamination Growth Rate (mm/cycle)
Cyclic Stress Intensity Range,
G (kJ/m
2
)
no z-pins
0.5% z-pins (thin)
2.0% z-pins (thin)
4.0% z-pins (thin)
32

Nanoparticle polymer composites


Nano
-
sized particles used to increase
stiffness, strength & toughness of
polymer matrix.



Carbon nanotubes much stiffer (1
-
5
TPa
) & stronger (13
-
130
GPa
) than
carbon fibres.



Graphene

also stiff & strong.



Future of
nano
-
particles uncertain.


Low cost production


Manufacturing


etc






33

Structural Health Monitoring

34

Non
-
destructive inspection

Damage to composites is insidious


hard to detect & reduces structural integrity


NDE techniques commonly used for
composites:



visual inspection



ultrasonics



radiography



thermography


NDE often slow, labour
-
intensive & may miss
damage.


Aerospace/aviation industry keen to apply
faster and smarter damage detection
techniques.

35

Structural health monitoring

Measurement and assessment of in
-
service structures on a
continuous basis with minimum human intervention


36

Structural health monitoring

37

Structural health monitoring

-
In
-
situ sensor networks (embedded
or surface
-
mounted) and intelligent
data processing


-
Essential ingredients for SHM

-
Inexpensive

-
Remote interrogation

-
Reliability

-
Durability

-
Detection of significant events
(impact, overload, etc)

-
Diagnostic capability

-
Prognostic capability


-
Still some way from achieving these
objectives

38

Fibre optic sensor

Piezoelectric
polymer film

piezoceramic
transducer

Miniature
accelerometer

Composite
materials allow
easy sensor
integration

Optical fibre embedded
in CFRP laminate

Structural health monitoring

39

Structural health monitoring


Bragg grating optical fibre sensors for
localised damage detection.


40

Damage

Structural health monitoring


Acousto
-
ultrasonics using PZT for wide
-
area damage detection in composite
structures.


Still a long way to go!


41

Concluding remarks


Giving an overview into future of composites for
aircraft is challenging & subjective.


Future will be determined by engineering expertise
& community expectations.


Australian engineers are and will continue to make
a global impact.


42

42

Concluding remarks


Giving an overview of future of composites for
aircraft is challenging & subjective.


The future is in the hands of engineering
expertise & community expectations.


Australian engineers are and will continue to
make a global impact.


Whatever the future holds it won’t be
boring!