itn waves - short course laboratory ultrasonic …

ITN WAVES - SHORT COURSELaboratory ultrasonic experimentation

Part 1 – TheoryPart 2 – Basic experiments

N. Favretto-CristiniB. Solymosi, P. Cristini

02/42

Introduction

Focus on

ultrasonic (US) experimentation in laboratory conditions

WAVES - Short course – US experimentation – N. Favretto-Cristini – june 2017

03/42

Introduction

Focus on


• 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


04/42

Introduction

Focus on



• Fast, repeatable, inexpensive, non-destructive technique


05/42

Introduction

Focus on




• 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


06/42

Introduction

Focus on





• 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


07/42

Introduction

Focus on






• 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


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Introduction

Focus on



• Fast, repeatable, inexpensive, non-invasive technique




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?


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Introduction

Focus on



• Fast, repeatable, inexpensive, non-invasive technique




• Why US experimentation for seismic purposes?

Laboratory experiments : perfect replica of reality?


10/42

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)


N. Favretto-Cristini

N. Favretto-Cristini, B. Solymosi, P. Cristini

11/42

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


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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


15/42


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)


PVC, Resins

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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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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


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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


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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


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Measurement of physical properties

of materials (evaluation of the associated

uncertainties)

Courtesy of LMA


QP

19

24

29

∞

∞

QS

29

36

46

∞

∞

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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


24/42

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


25/42

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


26/42


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


of the piezoelectric material

27/42


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)


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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


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Narrow- vs Broad-beam

Courtesy of LMA

Zero-offset acquisition

Classical beam width ~ 8.4°Broad-beam width ~ 45°


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


Courtesy of LMA

32/42

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


Courtesy of CEA Cadarache

33/42

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


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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

35/42

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



36/42

Wedge transducers

Propriété CIS - http://cis-ndt.com


Apps : NDT (detection and characterization of cracks…)

Time Of flight Diffraction

Cou

rtesy

Olympu

s-im

s.or

g


37/42

Comb transducers

Height of the strips thin compared to their width for LF,

thicker for HF

Lspatial = lSAW

Interdigital transducers

Perturbation of the surface


Apps : NDT (detection of sub-surface anomalies…)

Piezo transd.

Comb

StressesSAW

Surface Acoustic Waves


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Solid Wedge


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


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


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

itn waves - short course laboratory ultrasonic …

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