Smart Sensing and its Impact on Future Product Quality sensing - Christian Boller.pdf ·...
Transcript of Smart Sensing and its Impact on Future Product Quality sensing - Christian Boller.pdf ·...
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Smart Sensing and its Impact on Future Product Quality
Christian Boller�
Chair in NDT & QA (LZfPQ), Saarland University, Saarbrücken, Germany
6th CEOC - EUROLAB - IFIA International Safety Conference Brussels/Belgium, November 10, 2015
�
www.strassen.nrw.de
Ageing Infrastructure & Enhanced Maintenance Effort
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Lack of Quality in Civil Engineering
Source: www.matcoinc.com, www.engineeringcivil.com
Operational Quality of Pipeline Systems
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Source: FAZ
Source: Monitor
Source: WDR
Source: Spiegel
Quality in High Performance Structures
• Load (assumed) – Static Load: Ultimate Load – Fatigue Load:
• Constant Amplitude Load • Random Load (Service Load)
• Geometry (given) – Notches – Stress States/Multiaxial Loading
• Material (to be selected) – Strength – Ductility
Load
Applied Stress
Allowable Stress
Allowable Stress >
Applied Stress ?
Structural Design
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Critical Crack Length
Detectable Crack Length
Cra
ck L
engt
h
Number of Loading Cycles or Time
ΔN
Δa
Damage/Crack Propagation and Inspection
Inspection Interval 1
Crack Length
Life (Flight)
detectable
critical
Inspection Interval 2
Inspection Interval 3
Inspection Interval ...
No Crack Found
Crack!!! ΔN/2
Defined by design
Defined by inspection
From Safe Life to Fail Safe
Damage Tolerance (the tolerance to live with cracks) Inservice Inspection is part of the design (Inspectability) NDT-based inspection/maintenance plan is configured along structural and fatigue design and defines the ‚hot spots‘ (concurrent or simultaneous engineering);
Safe Life A component is replaced after a defined number of load cycles with no critical damage; No inservice inspection required (NDT)
Fail Safe A derivative of damage tolerance; components can fail while others take over the loads. Only relevant in the case of accidental damage.
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The use of noninvasive techniques to determine the integrity of a material, component or structure
or quantitatively measure some characteristic of an object.
i.e. Inspect or measure without doing harm.
Definition of Non-Destructive Testing (NDT)
Source: NSF, www.ndt-ed-org
What is mainly associated with NDT today?
• Standard – Visual – Vibrations – Ultrasonics – Eddy Current – X-Ray – Thermography – Microscopy
• Non-Standard – Acoustic Emission – Magnetics – Nuclear Magnetic
Resonance – Microwave/Radar – Optical Coatings – Nanoagents/-coatings
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Ultrasonics & Image Reconstruction
1x1 2x2 3x3 4x4 5x5 6x6 7x7 8x8 9x9 10x10 11x11 12x12 13x13 14x14 15x15 16x16
1
Phased Array Transducer
2 3
4
5 6
Phased Array Transducer
1
2 3
4
5 6
Off-line evaluation of clamp load by offline ultrasonic technique is state-of-art: The time-of-flight (TOF) of a longitudinal wave is measured before and after the fastening, clamp load and/or torque and/or elongation is calculated using appropriate calibrations.
L 0L ε
ΔL
U ltrason ic-p robeAmp litu d e
t-=2Lv
0
Δt#≈ ΔLΔt#≈ F, #σLo ng
Ultra
sonic-time8of
8flig
htUltra
sonic-pa
th-le
ngth
t -=2 (L + L )
v0 Δ
ε
Measuring Tensile Force by Ultrasonics
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N S
Hf-coil
Magnet yoke
Ultrasonic wave
Hall probe Cladding
EMAT-transducer for dynamic magnetostriction measurements
Electromagnetic Transduction
EC receiver coil
EMAT transmitter coil
EMAT receiver coil
Top view on coil
B
H
Saturation
Rotation
Irreversible motion Blochwall Pinning point
Reversible motion
Ferromagnetischer Werkstoff
Magnetic domains
Bloch walls
Externes Magnetfeld, H
Bloch wall movement
H H
Rotation
H
Ferromagnetic material External magnetic field, H
Microstructural Phenomena in Ferromagnetic Materials
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Barkhausen Effect
Heinrich Barkhausen (1881 – 1956)
Source: www.bbaw.de
Amplifier
Specimen
~ Actuator n.Elektromag
Simulated service time at 400°C [h]
Analogy between mechanical and magnetic hardness
EM measurement of hardness change due to copper precipitations in Cu-rich pressure steel 15 NiCuMoNb 5
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EM Measurement of Cyclic Fatigue
conventional measurand
ndt measurand
changes in micro- and macrostructure
e.g.
dis
loca
tion
reac
tion
form
atio
n an
d pr
opag
atio
n of
mic
rocr
acks
prop
agat
ion
of
mac
rocr
acks
incr
easi
ng
fatig
ue
dam
age
0.20
0.15
0.10
0.05
0.00 103 104 105
number of cycles
200
150
100
50
0
SAE 4140 σa = 620 MPa
Active Thermal Inspection Methods – Excitation by Ultrasound
Setup Sono-Thermography
IR Camera
Sonotrode
Specimen
Control unit
Time lapse Data acquisition Image processing Data analysis
Flaw IR Radiation
Ultrasonic transducer (50 W – 2.5 kW)
Sound (20 kHz)
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The Need for Automation in Inspection
• More than 99% of inspection results are ‘nor failures found’
Photo: Airbus Photo: Sandia Labs.
Structural Health Monitoring (SHM)
• … is the integration of sensing and possibly also actuation devices to allow the loading and damaging conditions of a structure to be recorded, analysed, localised and predicted in a way that non-destructive testing becomes an integral part of the structure. SHM is not an additional NDT application, nor QNDT, a fatigue analysis, vibration analysis, signal processing, material science or any other single technological area but rather lateral integration of all those in terms of a structure’s life cycle management.
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NDT Technologies Mainly Associated with SHM
• Acoustics – Guided Waves – Acoustic Emission – Piezoelectric Transducers
• Eddy Current – EM Foils
• Modal/Vibration Analysis • Miscellaneous
– Thermal – Comparative Vacuum
Monitoring
• NDT with SHM potential – Visual – Ultrasonics – Acoustic Emission – Vibrations – Magnetics/Eddy Current – Thermography – Optics – Nanoagents/-coatings
Fibre-Optic Bragg Grating Sensors for Loads Monitoring
Intensity
Spectrum
Intensity
Spectrum
Filter
Photodetector
Intensity
Spectrum
FBG 1 FBG 2 FBG 3
Input Output
Fibre Optic Bragg Grating
Bragg Grating
Bragg-Wavelength Core
refractive Index
refractive Index-Modulation
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Piezoelectric fibre actuators
Electrodes
Piezofibres
Polymer matrix
Active strain
Source: www.tau.ac.il & Airbus
Piezoelectric Sensing & Actuation
Electromagnetic Smart Skins
Source: UCLA, USA
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• Multi-layered (often 3) composite made of ferromagnetic layers (Fe- or Ni-alloys, Permalloy, 4-6nm) separated by paramagnetic, electric conductive layer (Cu, 3-5nm) of nm-thickness.
• Spin-coupling exists because of small thickness, resulting in closed domains along interfaces.
• Electric resistance of the device mainly influenced by scattering of the conductive electrons in the Cu-layer along the interfaces.
• For the antiparallel configuration Rel is high.
Giant Magneto Resistors (GMR)
No field:
domain moment vector directions
With field:
Current direction
Giant Magneto-Resistance- (GMR-) Sensor
Sensitive Direction
Detectable Crackdirection
Hallsensor GMR
Giant Magneto Resistors (GMR)
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crack indications
sensor array
Crack Detection with GMR Sensing
Source: Fraunhofer IZFP
3D Printed PCB Using Additive Manufacturing
Source: www.additivemanufacturing.com
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Switch Box
Amplifier Data Acquisition
Processor
Amplifier Waveform Generator
Smart Suitcase™ Smart Layer®
with 12 transducers
Smart Sensing System with 1 input and output
What is a Sensor in SHM?
Sensor = Sensor System
Non-Destructive Testing has a Mission
Quality &
Life Materials Characterisation Damage Detection
Manufacturing Processes
Life Cycle Management
NDT for: NDT for:
conventional future
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Example: Bridge over Highway 202 in Wayne/NJ, USA
Established: 1983 Cost to rebuild: 11,9 Mio. € Year of analysis: 2010 Condition: Acceptable with minor damage in the primary structure
Source: VCE, ViennaAustria
Analysis Result: Bridge Highway 202 in Wayne/NJ, USA
Corrosion in Support Bearings
Enhanced dynamic loading due to settlement and increased traffic
Source: VCE, Vienna/Austria
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Residual Life: Bridge Highway 202 in Wayne/NJ, USA
No additional measures take Residual life 17 years Maintenance cost: 506 k€
Additional maintenance on support and deck structure, sealant and bearings Residual life 25 years Maintenance cost: 1.155 k€
Additional maintenance on support & deck structure, sealnat and bearings; modified structural dynamics Residual life 32 years Maintenance cost: 1.363 k€
1983 2103
Source: VCE, Vienna/Austria
Conclusion: Bridge Highway 202 in Wayne/NJ, USA
857 k€ invested today will allow a new investment of 11.900 k€ to be delayed by 15 years and will save the public 3.100 k€. This
is just one out of countless examples. 1983 2103
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Conclusion Monitoring Infrastructure has a Value
The Impacts
• Longer operational life (or lighter weight design) • Higher resource efficiency • Higher operational reliability • Lower operational cost • Enhanced sensor integration • More data management • ‚Smarter‘ structures