ITN WAVES - SHORT COURSELaboratory ultrasonic experimentation
Part 1 – TheoryPart 2 – Basic experiments
N. Favretto-CristiniB. Solymosi, P. Cristini
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Introduction
Focus on
ultrasonic (US) experimentation in laboratory conditions
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Introduction
Focus on
ultrasonic (US) experimentation in laboratory conditions
• Classical way to inspect materials & structures in various domains and for various apps
Structure Health Monitoring (SHM)
Non-Destructive Testing (NDT/E)
Medical imaging
Echography
Echo-Doppler
Reflectivity of tissues,
blood flow… Detection of cracks, holes…
Evaluation of welding…
Courtesy of Imagerie RennesCourtesy of LMA
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Introduction
Focus on
ultrasonic (US) experimentation in laboratory conditions
• Classical way to inspect materials & structures in various domains and for various apps
• Fast, repeatable, inexpensive, non-destructive technique
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Introduction
Focus on
ultrasonic (US) experimentation in laboratory conditions
• Classical way to inspect materials & structures in various domains and for various apps
• Fast, repeatable, inexpensive, non-destructive technique
• Bulk waves (P & S), Surface waves, Guided waves
Animation courtesy of Dr D. Russell, Kettering Univ.
P-wave curl UP = 0Rayleigh wave = linear combination of
P- and SV-waves
Specific properties and existence conditions
Not a head wave!
SV-wave div US = 0
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Introduction
Focus on
ultrasonic (US) experimentation in laboratory conditions
• Classical way to inspect materials & structures in various domains and for various apps
• Fast, repeatable, inexpensive, non-destructive technique
• Bulk waves (P & S), Surface waves, Guided waves
• Active / Passive acoustics
Active acoustics
Source Receivers
SourcePassive acoustics
Temps (s)
Am
plit
ud
e (V
)
Co
ntr
ain
te a
pp
liqu
ée
(MP
a)
0
200
400
100
600500
300
0 1 2 3 4 5 6 7 8 9
1 2 3
Courtesy of LMA
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Introduction
Focus on
ultrasonic (US) experimentation in laboratory conditions
• Classical way to inspect materials & structures in various domains and for various apps
• Fast, repeatable, inexpensive, non-destructive technique
• Bulk waves (P & S), Surface waves, Guided waves
• Active / Passive acoustics
• Wide frequency range
Freq.
0
Seismology
Land Seismics
Marine SeismicsUnderwater acoustics
100 Hz < f < 800 kHz
Ultrasound
20 kHz 20 MHz
SoundInfrasound
20 HzNDT
Medical imaging1 < f < 20 MHz
100 kHz < f < 10 MHz
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Introduction
Focus on
ultrasonic (US) experimentation in laboratory conditions
• Classical way to inspect materials & structures in various domains and for various apps
• Fast, repeatable, inexpensive, non-invasive technique
• Bulk waves (P & S), Surface waves, Guided waves
• Active / Passive acoustics
• Wide frequency range
Numerical modeling
& inversionLaboratory experiments Field observations
Physical (real) data in a controlled environment
Tool for development & testing of new theories/ideas and numerical methods
Tool for investigation of physics not sufficiently understood
• Why US experimentation for seismic purposes?
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Introduction
Focus on
ultrasonic (US) experimentation in laboratory conditions
• Classical way to inspect materials & structures in various domains and for various apps
• Fast, repeatable, inexpensive, non-invasive technique
• Bulk waves (P & S), Surface waves, Guided waves
• Active / Passive acoustics
• Wide frequency range
• Why US experimentation for seismic purposes?
Laboratory experiments : perfect replica of reality?
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Course content
Part 1 - Theory
Which objective? Which configuration?
How determining the scale ratio?
How designing the small-scale model?
How acquiring data? ----- Source/receiver, experimental setup
Part 2 – Basic experiments
Introduction to lab exercises : measurements of material properties (VP,S ; aP,S)
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
N. Favretto-Cristini
N. Favretto-Cristini, B. Solymosi, P. Cristini
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Objective? Real configuration?
Seismic-reflection : land or marine?
Borehole – VSP
Surface waves
Active / passive acoustics
(microseismicity = acoustic emission)
What’s your dream?
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Design of the small-scale configuration
Not seismics towards lab, but rather
Lab Seismics
Technical and techological issues
• properties of materials
• carving/manufacturing the model
• sources/receivers
• electronic devices (e.g., a large nb of S/R)
• acquisition design
• facilities & environment (noise, EM…) …
Cost ….
Welcome back to reality!
Courtesy of LMA
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Solve the problem step by step
1. real configuration/issue
2. frequencies/wavelengths of interest
3. scale ratio
4. sources and receivers at the lab scale
5. acquisition design at the lab scale
6. small-scale model
Typical scale ratio
~ 1:10 000 or 1:20 000
(for seismics)
Design of the small-scale configuration
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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For illustration purpose : the WAVES model
Courtesy of UFP Porto
Understanding complex wave propagation
Accuracy of numerical methods for modeling wave propagation
Challenging for imaging methods
Courtesy of NPD
Courtesy of MIT-ERL
Geological context
Salt bodies (hydrocarbon traps)
Structural and physical complexities
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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For illustration purpose : the WAVES model
Courtesy of LMA
Cou
rtesy
ofMIT-E
RL
Broad-beam
source
500 kHz Receiver
Marine seismic-reflection surveyOur initial target
Our constraints
Our « dream »
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Physical properties of Materials
o Liquid, solid?
o Homogeneous/heterogeneous?
o Isotropic/anisotropic?
o Elastic, viscoelastic, porous…?
Design of the small-scale model
« Real » media (µ/macroscale heterogeneities)
Resins, plastic materials (sediments)
Composites (aniso media)
Metals (rocks)
Aluminum
Glass, Crystal
Courtesy of Lavergne (1986)
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
PVC, Resins
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Design of the small-scale model
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
Aluminum
Glass, Crystal
QP
30-70 40-60 20-50
70-150
70-150
100-600
100-600
200-600
o Liquid, solid?
o Homogeneous/heterogeneous?
o Isotropic/anisotropic?
o Elastic, viscoelastic, porous…?
« Real » media, Resins, plastic
materials, Composites, Metals
Courtesy of Lavergne (1986)
Attenuation = crucial issue(not perfect replica of real media)
PVC, Resins
Physical properties of Materials
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Design of the small-scale model
Geometry
Specific machines (3D printers, carving machines, autoclave…)
Specific conditions (e.g., vacuum, under load/stress, high temperature…)
Mechanical/chemical bonds (thin layers may be thick for US waves)
…
o Specific shape? Curved interfaces?
o Layered medium? Contact between layers?
o Characteristic lengths/thicknesses? Size?
Marseille model
Courtesy of LMA
Courtesy of LMA
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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WAVES model
For illustration purpose : the WAVES model
Designing the small-scale model = definitely, the trickiest
and most time-consuming step!2 years! 35 k€!
Materials
o Salt body
‒ Make a prototype using a 3D printer (mould)
‒ Find a specialist (more than 6 months!) able to manufacture such a « huge » volume
without internal micro-bubbles (highly challenging!)
‒ Various tests - Specific crystal (45% of PbO instead of 24%)
Courtesy of LMA
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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For illustration purpose : the WAVES model
o Sedimentary layers
‒ Many work meetings with a company able to manufacture such a model
‒ Resins filled with various amounts of aluminum and silicea powders + specific
manufacturing process in order to avoid micro-bubbles and density gradients –
Various tests
‒ Full size of the model constrained by technical and physical (attenuation) issues,
therefore smaller than initially planned
‒ Curved interfaces – Perfect mechanical contact between layers
‒ Control of non-existence of micro-bubbles (echography) + Scan of each layer at
each step of the manufacturing process
WAVES model
Courtesy of LMA
Courtesy of LMA
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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For illustration purpose : the WAVES model
Measurement of physical properties
of materials (evaluation of the associated
uncertainties)
Courtesy of LMA
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
QP
19
24
29
∞
∞
QS
29
36
46
∞
∞
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For illustration purpose : the WAVES model
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Acquisition design
Courtesy of LMA
Broad-beam
source
500 kHz Receiver
Marine seismic-reflection survey
How acquiring data? ----- Source/receiver + Experimental setup
depending on the goal of the studyCourtesy of LMA
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Sources / Receivers
o P- or S-wave?
o Source only, receiver only, or source & receiver?
o Immersed system? Contact system?
o Single element or array of elements?
o Frequency and bandwidth?
o Response?
o Directivity : narrow or broad beam, focused beam?
Some preliminary questions
Classical S and/or R
o Piezoelectric transducers, Hydrophones
o US sensors
o Laser (interferometer)
Specific S/R for specific apps
Courtesy of IFSTTAR
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S/R : Piezoelectric transducers
o Active element : piece of polarized material (piezoelectric ceramic) sandwiched between
electrodes
o Impedance matching layer : in order to get as much energy out of the transducer as
possible - For contact (respectively, immersion) transducers, made of a material with
acoustical impedance between the active element and steel (respectively, water)
o Backing material : great influence on the penetration/sensitivity characteristics of a
transducerContact transducers need a coupling medium (usually liquid, gel or
« honey ») that enhances the energy transmission into the solid
Courtesy nde-ed.org
• P- or S-wave transducers
• S, R or S/R
• Immersed or contact system
Electrical signals Mechanical vibrations
Emission
Reception
Courtesy nde-ed.org
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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S/R : Piezoelectric transducers
Response / Frequency / Bandwidth
Piezoelectric Transducer 1 MHz
Bandwidth ~ 1 MHz
Operating frequency determined from
o the sound speed
o the thickness (l/2)
Bandwidth
Courtesy of LMA
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
of the piezoelectric material
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S/R : Piezoelectric transducers
Near field / Far field
For instance (in water)
o for a 500 kHz - transducer (diam. 2.54 cm) : 5.4 cm
o for a 1 MHz - transducer (diam. 1.27 cm) : 2.7 cm
o for a 1 MHz - transducer (diam. 0.3 cm) : 0.15 cm
(Fresnel zone)
N = D2 / 4l
N increases with increasing D (fixed frequency) or with increasing frequency (fixed diameter)
Courte
synd
e-ed.org
Courtesy Olympus-ims.com (Fraunhofer zone)
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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S/R : Piezoelectric transducers
Radiation pattern
o Spatial Fourier Transform of a disk
o Main lobe (high energy) and secondary lobes
o Width qc of the main lobe given by the 1st zero of the
Bessel function which gives sin qc ≈ qc ≈ 1.22 l/D
x
xJH 12q
l
q
sinDx with
Best directivity for big diameter (fixed freq.),
or for high freq (fixed diameter)
o Log scale : 20 log10 (A/A0) ampl. decrease
usually radiation pattern given for
- 3 dB <--> 71%, - 6 dB <--> 50%
Courtesy fao.org
Oblique incidence
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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S/R : Piezoelectric transducers
Narrow- vs Broad-beam
Courtesy of LMA
Zero-offset acquisition
Classical beam width ~ 8.4°Broad-beam width ~ 45°
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
S/R : Piezoelectric transducersTantsereva et al. (2014) Geophysics
Line Y 250
Line Y 250 Line Y 200
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017 30/42
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Receivers
Hydrophones
o P-wave
o Mainly R
o Immersed system
o Associated
preamplifier
Radiation patterns
in the horizontal / in the vertical planeFrequency spectrum
Courtesy of Reson
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
Courtesy of LMA
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Receivers
US sensors (acoustic emission)
o P-, S-wave
o R
o Contact system (coupling)
o Resonant or wide-band (related to sensitivity)
Temps (µs)
0
0 7000
0,08
-0,08
0,04
-0,04Am
plit
ud
e (
V)
Fréquence (kHz)0
0 1000
1500
Am
plit
ud
e (-
)
125
225
Frequency bandwidth few kHz - 1 MHz
Resonance frequencies due to modes
of vibration (thickness and radial)
Favretto-Cristini et al. (2016) Ultrasonics
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
Courtesy of CEA Cadarache
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Specific Sources & Receivers for specific apps
Focused transducers
Focal depth
Cou
rtesy
Olympu
s-im
s.org
Cou
rtesy
Olympu
s-im
s.org
Courte
syantoine
-education.co.uk
Manzi et al. (2010) JASA
Apps : medical imaging
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Specific Sources & Receivers for specific apps
Phased-array transducers o Multi-elements
o Dephasing
o Real-time control
o Multi-channel acquisition
or sectorial scanning
Apps : NDT (weld inspection, cracks detection)
Medical imaging
Constant phase-front
Cou
rtesy
Olympu
s-im
s.org
Animationco
urte
sycis-nd
t.co
m
Courtesy ob-ultrasound.netWAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Dual-element transducers
Apps : NDT (thickness gauging of thin materials, corrosion)
1 source/1 receiver in 1 housing
Cou
rtesy
mi-nd
t.co
mCou
rtesy
elcom
ete
r.co
m
Cou
rtesy
Olympu
s-im
s.org
Specific Sources & Receivers for specific apps
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
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Wedge transducers
Propriété CIS - http://cis-ndt.com
Specific Sources & Receivers for specific apps
Apps : NDT (detection and characterization of cracks…)
Time Of flight Diffraction
Cou
rtesy
Olympu
s-im
s.or
g
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Comb transducers
Height of the strips thin compared to their width for LF,
thicker for HF
Lspatial = lSAW
Interdigital transducers
Perturbation of the surface
Specific Sources & Receivers for specific apps
Apps : NDT (detection of sub-surface anomalies…)
Piezo transd.
Comb
StressesSAW
Surface Acoustic Waves
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Solid Wedge
Specific Sources & Receivers for specific apps
Surface Acoustic WavesApps : NDT (detection of sub-surface anomalies…)
sin qinc = Vsolid wedge / VSAW
SAWq = 90°
VSAW < VP , VS
P or S-wave Piezo transd.
Which material for the wedge?
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Diffraction gratings
Reciprocity
Specific Sources & Receivers for specific apps
Apps : NDT (detection of sub-surface anomalies…)Surface Acoustic Waves
Lspatial = lSAW
Perturbation of the surface
SAW
Piezo transd.
Water
Solid
Lspatial
Liquid Wedges
q
sin q = Vliquid wedge / VSAW
Water
Solid
SAW
Piezo transd.
Liq.
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Data acquisition
Defining electronic devices / experimental setup corresponding to the needs
o Pulse generator / function generator
o Preamplifier
o Increasing the Signal-to-Noise ratio : average (stack), time delay
o Acquisition : sampling frequency, nb of points (samples)
Nyquist-Shannon
Sampling at freq Fe can transmit without loss of
information only freq < Fe/2
Too low : loss of info
Too high : transmission of info, storage (memory)…
Electronic devices when a huge
number of receivers
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Data acquisition
Typical experimental (pulse-echo) setup for wave reflection/transmission
Pulse generatorRep. Rate, Energy,
Attenuation, Filter
OscilloscopePreamplifier
Acquisition systemSampling rate, nb samples,
time delay, …
Trigger
Output
signal
Trigger
Trigger
Signal
S R
Signal
Data processing depending on what is
needed (FT, time-frequency analysis,
cross-correlation …)
Input signal = pulse
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Part 2 : Introduction to lab exercises
WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017
Measurements of material properties
Use 1 sample or 2 samples with different thicknesses
o VP,S (m/s) : difference in traveltime
o aP,S (dB/m) : difference in amplitude
Source : pulse convolved by the response of the transducer or pure sine
Dispersion effects