2. Overview
Life1. Objective
cycle of a composite structure
Production and assembly monitoring
2. Rationale
A. Production and
Application monitoring assembly monitoring
B. Operation/Health monitoring
Opportunities
3. Sensor technologies
Novel Envisaged applications
4. technologies
5. Research consortium
6. Research
Applications approach
7. Industrial user consortium
Health monitoring in marine environment
3. MANUFACTURING
Life cycle of a composite structure
Use Phase
Assembly
Assembly
Assembly
Assembly
“Life cycle monitoring of large-scale CFRP VARTM structure
by fiber-optic-based distributed sensing,”
S. Minakuchi, et. al., Composites Part A, 42(6),669-676 (2011)
6. Production monitoring & opportunities
Production
Today
Thermocouples
Pressure sensors
Ultrasonic inspection
No sensor able to predict initial strain state!
Opportunities
Initial strain state (residual strains)
e.g. with embedded sensors (Fiber optics,
Polymer waveguides,…)
In-situ Cure monitoring
e.g. with ultrasonic transducers, Fresnel reflection,
capacitive sensing,…
NECESSITY FOR MULTI-INSTRUMENTATION
9. Combination of Optical fibers and Ultrasound
1
Gelation
2
Temperature
FBG strain
Residual strain magnitude
Ultrasound
2 regions:
1. Composite does not exist! Resin in a fluid state
2. Composite exist
strain transfer
10. Assembly monitoring & opportunities
Assembly
+
Finishing
Today
Visual inspection
Opportunities
Embed sensors in adhesive zone
Use finishing layer as sensor (coating)?
Ageing sensors?
Impact damage, tool drop
Speed of monitoring
event measurement or offline monitoring
12. Application monitoring & opportunities
Design
Today
Visual inspection
Load monitoring (edge, flap, combined)
External strain gauges
No information from the inside
Exploitation
Opportunities
Pitch control (blade deformation)
predict life time blades
Use material as sensor (CNT, CB,…),
Digital Image Correlation?
Design support tool
Reduce costly inspection
13. Pitch control monitoring
MOOG inc: System to Adjust
Windmill Wing Pitch Angle
Provide edgewise and flap
wise bending moment data
to the individual pitch
control system.
10-20% of load reduction in
the blades
20-30% in the main shaft
Life time ↑↑
www.moog.com/markets/
energy/wind-turbines/
14. Composite life cycle monitoring: Opportunities
Difficulties
Read-out and integration
Cost and size of interrogator system
Go for less performing system?
More dedicated?
Cheaper?
Number of sensors needed to monitor structure?
The least possible (design or exploitation)
Reparability: Sensor should survive the structure
with 100% certainty or possibility for repair
Prediction of Eigenfrequencies
via online strain date
Relation of the sensor signal with the real situation
18. Structural Health Monitoring
applied to Marine Applications
Development of FBG sensors based on silica &
plastic optical fibres
Investigating sensor embedding processes and
positioning the optical fibres at different layers
according to the strains to monitor
Developing a complete catamaran in carbon fibre
reinforced polymer which will be used for further
investigation and embedding of smart
components
19. Structural Health Monitoring
applied to Marine Applications
Developing low cost optical interrogator
Physical validation for finite element simulation
• Real-time strain monitoring
• Composite material properties investigation
• Broken down and failure detection
20. Structural Health Monitoring
applied to Marine Applications
Sensor
Evolution
Simulation
Sensor
Interrogation
Sensor
Embedding
Sensor
Fabrication
21. Preliminary tests
• More then 60 FBGs were glued on the catamaran mast
• FBGs realized by the phase mask technique.
• Chirped phase mask: 15nm/cm, length of each FBG: 1mm
Shrouds
Fibre Bragg gratings
Location of the future
housing connectors
Spreader
1.10m
0.70m
0.70m
8.90m
9.25m
15.25m
17.75m
Front view: Schematic representation
22. Preliminary tests
Fibre n°1
Fibre n°3
Fibre n°2
Fibre n°4
Fibres n°2, 5
and 8
Fibre n°6
Fibre n°5
Fibres n°1,
4 and 7
Fibres n°3, 6
and 9
350 mm
190 mm
Shape of the mast base
Fibre n°7
Fibre n°9
Fibre n°8
Location of the future
housing connectors
Base of the mast
28. Preliminary tests
Schematic representation of the mast during this test
We follow the evolution of the Bragg wavelength of the FBGs.
As expected:
The Bragg wavelength shifts of the FBGs of the fibres n°1, 3,
4, 6, 7 and 9 are very small
The FBGs of the fibres n° 2, 5 and 8 are under compression
30. Preliminary tests
Mast is let free and is only maintained at both
extremities but turned on its side
31. Preliminary tests
We follow the evolution of the Bragg wavelength of the FBGs.
As expected:
The Bragg wavelength shifts of the FBGs of the fibres n°1, 4
and 7 are under traction.
The Bragg wavelength shifts of the FBGs of the fibres n°3, 6
and 9 are under compression.
Bragg wavelength shift
(pm)
Fibre n°4
Fibre n°6
600
400
200
0
-200
-400
-600
1
3
5
N° of the FBG
7
32. 2nd phase: Embedding
- Realisation of small
grooves
- Optical fibers embedding
- Filling of the grooves and
protection of the sensors
with epoxy glue
34. 2nd phase: Embedding
MPO (Multi-fiber Push-On) connector
between the mast and the interrogator
Rapid prototyping of a waterproof
housing for the connection.
This one will be attached to the mast
35. Interrogator set-up
FBG 1
FBG x
FBG 1
FBG x
FBG 1
FBG x
Optical circulator
…
e-LED
Photodiode &
Data processing
Tunable filter
Light, small size, low power consuming