imaging in non-destructive testing
TRANSCRIPT
Imaging in Non-Destructive Testing
W. Arnold, M. Kröning, and F. WalteFraunhofer-Institute for Non-Destructive Testing
Bldg. E 3.1, UniversityD-66123 Saarbrücken, Germany
1929: Sokolov (Russia) notices that with ultrasound defect can be detected in metals. He calls this signal on the scope a reflectogram.
1945: Delano (Sperry Inc. USA) names this reflectogram an A-scan A- Scan.
Reflectogram of a defect in a steel shaft
Source: L. Bergmann, Ultraschall 1954
Imaging in Non-Destructive Testing: A-Scan
1935: Sokolov (Russia) andPohlmann (Germany)develop the first ultrasonic imaging system.
Source: L. Bergmann, Ultraschall 1954
Imaging in Non-Destructive Testing
Ultrasonic imaging system after Sokolov/Pohlmann
UV- light
Electrostatic lens
Magnetic lens
Piezoelectriccrystal
Object with defect
Lens Piezoelectric plate with photoelectric layer = Cathode of the image converter
Source: L. Bergmann, Ultraschall1954
Imaging in Non-Destructive Testing
Two with screws joined metallic blocs
Frequency = 7 MHz
Source: L. Bergmann, Ultraschall 1954
Ultrasonic imaging system after Sokolov/Pohlmann
Imaging in Non-Destructive Testing
Amplitude Scan: A- Scan
xz
A
BWE
DE
y
Defect
z
1945: Delano (Sperry Inc., USA)calls the reflectogram A-scanas an abbreviation for amplitude-scan
Imaging in Non-Destructive Testing
1954: Leksell (USA) 1. Ultrasonic B-scans in medical imaging. A- scans are added in analog fashion and defect-echoes are depicted as amplitude modulated images.
B-scans stands for Brightness Image.
Source: Geschichte der Ultraschall- Diagnostik. Ultraschall Museum im Deutschen Röntgen-Museum
Imaging in Non-Destructive Testing
Brightness Scan: B- Scan
xz
A
BWE
DE
y
Defect
z
x
DE
BWEz
Amplitude Scan: A- Scan
Brightness-scan = B-scan in NDT
The amplitude is color coded in a typical B- Scan in a modern NDT imaging system
Imaging in Non-Destructive Testing
1957: Michalskie (Germany/Röchling, Saarland) carries out one the first B-scans tests in NDT.
Images of inclusions in a steel shaft
Source: Chronik der zfP. U. Richter, DVS- Verlag 1999
Imaging in Non-Destructive Testing
Acoustic signal(Tone-burst)
Reference signal
Plane wave
Object wave
Object Reference wave
Acoustic Holography
1954: Greguss, Hungary develops in analogy to optical holography acoustical holography.
Imaging in Non-Destructive Testing
Object signal Reference signal
Multiplication
Digital storage
Analog storage
Storage on PC
Photodiode
Storage on hologram plate
1976: Holosonics (USA) constructs the first commercially availableholographic system with analog recording and optical reconstruction.
1979: Schmitz (IZFP) and Kutzner(BAM) develop holographic systems with digital recording and numericalreconstruction.
Imaging in Non-Destructive Testing
LASER
Aperture Mirror
Mirror
TV- CameraHologram plate
Display
Acoustical holography withoptical reconstruction
Imaging in Non-Destructive Testing
Digitally storedsignal
PC Holography algorithm(Back-propagation)
Display
Acoustical holography with numerical reconstruction
∫ ∫= ηρλ
dderizuu ikr
212
Imaging in Non-Destructive Testing
x – y plane at z1
Holography
Result: ultrasound amplitude distribution in y-x plane
Rekonstruktion using backpropagationA
xz
y
Defectz 1
zo
Measurement:Real- and imaginary partof ultrasound in x-y plane at zo
A
t
Real
Imag
Imaging in Non-Destructive Testing
Holography in tandem – and pulse-echo mode
Specimen with flat-bottom holeswith different orientation
Optical reconstruction
Pulse Echo Tandem Quelle: V. Schmitz and M Wosnitza, Erfahrungen der Ultraschallholographie mit numerischer und optischer Rekonstruktion
Imaging in Non-Destructive Testing
Holography in pulse-echo and pitch-catch mode
Specimen with a side-drilled hole
Numerical reconstruction
Source: J. Kutzner, H. Wüstenberg BAM- Berlin
Imaging in Non-Destructive Testing
1979: Holography system (IZFP) based on the unit from Holosonics Inc. USA
Imaging in Non-Destructive Testing
Specimen with slag inclusions
0ptical reconstruction Numerical reconstruction for line A-A
A A
Application of acoustical holography in the inspection of welds
Source: V. Schmitz, M. Wosnitza. Erfahrungen der Ultraschallholographie mit numerischer und optischer Rekonstruktion
Imaging in Non-Destructive Testing
x
yz
C - Scanx
y
1955: Projection of the ultrasonic amplitude as projection on the area scanned: C- Scan.
Imaging in Non-Destructive Testing
FV
SV
TVFV: Front viewTV: Top view
SV: Side view
1973: Based on C-scans Lund & Jensen (Denmark) develop the P-Scan technique (projection-scan)
Imaging in Non-Destructive Testing
15 mm
15 mm
3 mm 2 mm
UT- Probe: 2 MHz, 70 ° P- wave
1985: C- scan technique (IZFP/CPSN) for austenitic welds seams.The double indications originate from the direct P-wave and the mode converted signal SPP.
Imaging in Non-Destructive Testing
Ultraschallfront
Fokus
FokussierungWinkeleinschallung
θ
1968: First proposal of a phased array testing system in the USA
Imaging in Non-Destructive Testing
Control Unit
Timedelay
Timedelay
Timedelay
T T TR R R
α
Dd
α
Time delay D = d sin α
D
Variable insonification angle
Block model ofphased-array system
Imaging in Non-Destructive Testing
1 2 N3
Digitizer
Multiplexer
Preamplifier
Phased-Array Electronics Computer
Phased-Array Probe
Transmitter device32 channels
Max. time delay = 8 μs
Bandwidth 0.5- 8 MHz
Receiver device
32 channel analog multiplexer
100 MHz digitizer
Computer At- 386 / 33 MHz
1979: Gebhardt (IZFP)carries out the first measurements in NDT using a Phased-Array in Germany
Imaging in Non-Destructive Testing
1 m
1/2 m
1980: IZFP phased array-system “ARGUSS“
Imaging in Non-Destructive Testing
xz
y
Defect
y1
α
COMPOUND- Scanwith
Phased Arrays
Measurement:
Sector-Scans (A, z, a )
Reconstruction by superposition of video-signals in x- z plane at y1
Result: Amplitude distribution in the x-z plane at y1
1980: Gebhardt (IZFP) develops the COMPOUND-Scan in NDT
Imaging in Non-Destructive Testing
32 °
20 mm φ
130 mm 100 mm
Phased Array COMPOUND- Scan
Application of a COMPOUND- Scans
Source: W. Gebhardt. F. Bonitz, H. Woll, V. Schmitz. Beam Forming and Defect Characterization by Phased Array Systems. 9. World Conf. on NDT
Imaging in Non-Destructive Testing
xz
y
Defect
y1
Atm1
t m2tm3
t
1978: Barbian (IZFP) develops ALOKAmplitude and time-of-flight LOCUS Curve
Measurement:of time of flight (t) for each (A max) of all RF-signals in x-z plane at y1
Reconstruction by points of intersection in x- z plane at y1
Result:Reflection points in x-z plane at y1
Imaging in Non-Destructive Testing
Inspection of RPV- NozzleALOK- reconstruction
of notches (saw cuts) in the nozzle corner
notch
Imaging in Non-Destructive Testing
1987: ALOK-3 unit (IZFP)For ndt of components of the primary circuit of nuclear power plants
Imaging in Non-Destructive Testing
Ultrasonic Inspection for 40 – 56‘‘Pipelines
Insertion into a 40‘‘pipeline
Transducer made ofpiezoelectric material
Imaging in Non-Destructive Testing
Abb. 1.2.4.1 Synthetisierung der Apertur durch Abtasten des Prüfobjekts
1972: Based on radar technology Prine (USA) develops the “Synthetic Aperture Focus Technique“ (SAFT).
By scanning a small transducer on the component to be tested, a synthetic aperture is built. All rf-signals are stored and their origin is numerically calculated and the source displayed as defect.
Imaging in Non-Destructive Testing
xz
y
Defect
y1
A
t
SAFTSynthetic Aperture Focusing Technique
Measurement of all RF wave-forms on the line y1
Reconstruction by circles with time depending summation of all RF- amplitudes
Result: SAFT- B- Scan for x-zplane at y1
Imaging in Non-Destructive Testing
SAFT- reconstruction of a crack in a circumferential weld, wall thickness 30 mm
70° insonification of a transverse wave
Imaging in Non-Destructive Testing
Austenitic weld UT- probe 2.25 MHz, 60°, P-
Wave
Hot crack 50 mm
Crack tip; Direct echo
Back wall
Angle mirror effect (Sv- P- Sv)
Test of austenitic weld using SAFT
Imaging in Non-Destructive Testing
xz
yy1
A
t
Defect
Reconstruction: B- Scan in x- z plane at y1
Measurement of allRF- waveforms
Two transducers in pitch-catch mode
1975: Silk (GB)Time-of-FlightDiffraction TechniqueTOFDT
Imaging in Non-Destructive Testing
Time-of-Flight Diffraction Technique TOFDT
Side drill holes
TOFDT- B- Scan
Source: J.P. Charlesworth, J.A.G. Temple: Ultrasonic Time-of-Flight Diffraction: John Wiley & Sons Inc. 1989
Imaging in Non-Destructive Testing
α
A11 A12 A13 A14A21 A22 A23 A24A31 A32 A33 A34A41 A42 A43 A44
Σi2Σi1 Σi3 Σi4
i
j
1 2 3 4
Pixel-field
ΣΑij
Transmitter Elements
Receiver Elements
Transmitter time-delay
Receiver time-delay
2005: Using the powerful computers available now, Andrei Boulavinov (IZFP)develops the sampling phased array (SPA) whose basic principle has been formulated by various groups previouslyP. Wilcox et al, Bristol, Chiao and Thomas,GE Schenectady, Ozaki et al, Mitshubishi
Conventional Phased Array:With N elements one obtains only a sub-number of the matrix based on n signals
The functions Ultrasonic beam sweepingFocusingSectors-canSAFT- reconstructionCOMPOUND- scan
must be carried out consecutively by acquiring new data
Conventional Phased Array
Imaging in Non-Destructive Testing
Sampling Phased Array (SPA)
a
A11A12A13A14A21A22A23A24A31A32A33A34A41A42A43A44
i
j
1 2 3 4
A11A21
A31A41
A14A24
A34A44
Pixel-field
ΣΑij
Transmitter elements
Receiver elements
i): First element transmits, all elements receiveii): Second elements transmits, all elements receive
Filling up the complete matrix with N elements, oneobtains N2 data, allowing one
Beam sweepingFocusingSector-scanSAFT reconstructionCOMPOUND-scan
All functions can be realized in one test.
Data matrix of information
Imaging in Non-Destructive Testing
Electronics
Gruppenstrahler 16 Elemente
Mobiler PC
Sampling Phased Array (IZFP)
Phased array transducer with 16 elements
Laptop PC Specifications:
Synthetic transmitting channels:16 - 1024
No. of channels: 16 - 64Dynamic range: 110 dBSignal depth ADC: 14 BitMaximal digitization rate: 80 MHzMaximal IFF: q0 kHz
Imaging in Non-Destructive Testing
Crack
Angle mirror Backwall
Application: Sampling Phased Array SynFo- reconstruction
Corresponds to SAFT- reconstruction based on a stationary probe position with redundant data acquisition
+/- 65°
Stationary SAFT- Inspection (manual)
50 mm
25 mm
P-wave
Phased Array Probe16 Elements
Isotropic material
Natural crack
Imaging in Non-Destructive Testing
Sampling Phased ArrayComplete Information Matrix
Inspection Volume
Phased Array Probe Phased Array Probe
COMPOUND- Scan with SPA
Imaging in Non-Destructive Testing
Inspection of turbine axleusing SPA- COMPOUND- scan
0°21° - 21°
7°14°
Side-drilled holes 3 mm φ
0°7°14°- 21°21°
Imaging in Non-Destructive Testing
Test flaw 1
Test flaw 2
Test flaw 3
Test flaw 4
Reconstruction without depth compensation
Application: Sampling Phased Array
Specimen with 4 side-drilled holes2 mm φ
Imaging in Non-Destructive Testing
SF-phased array without focusing
Back-wall signal
Artificial defect
GT- phased-array with inverse phase-matching
Phased-array probe on component
Back-wall signalArtificial defect
SPA: First Application on anisotropic composite materials
Imaging in Non-Destructive Testing
30 30
84
114
24θ1
θ2
134
θ3
θ4
Nr. 3
Nr. 4
R2R3
R4
R2’’
BWER3’’
Nr. 2
Nr. 1
R5 (edge)
θ5
Application: SPAsector-scan
Imaging in Non-Destructive Testing
•Acoustic Microscopy (SAM)
•Atomic Force Acoustic Microscopy (AFAM)
Imaging in Non-Destructive Testing: Surface Characterization
Imaging in Non-Destructive Testing: Acoustic Microscopy
07.11.01
Electronics Image Processing
(a), (b): Scanning directions of the lens
TransducerSurface Acoustic Wave
Geometrical Focus
SurfaceSapphire
4
5 8
2
1
109
6
7
3
20μm
SAM Image of a Rock Sample
20 μm
Frequency 1 GHz
Measurement of Acoustic Impedance with the SAM
Cu
Al
Epoxy
Ni
Mg
Si
W
Acoustic impedanceZ = ρ × v
Calibration curve for acoustic impedance
acoustic image of sandstone with clay cement: what is contact stiffness?
Contact Zone in Sandstone
quartz
pore space
clay cement
500 µm 62.5 µmAcoustic images of a sandstone with clay cement made at 1 GHz. Impedances in the AM image is coded by gray shades: black = low impedance pore space, and light gray to white = high impedance quartz grains. The gray scale in the image extends from 45 Mrayls (white) to about 3 Mrayls (black). The right image show details of the clay contact zone with significantly lower impedance that the quartz.
Rayleigh wave velocity in Al2O3 from V(z) measurements
High-Resolution Testing of Piezoelectric Ceramics by Atomic Force Acoustic Microscopy Techniques
Atomic-Force Microscope
Deflection
Sample
Sensor tip
Micro-fabricatedcantilever
230 μm
*mk
f2 C00 =π⋅=ω
Harmonic oscillator model:
Typical values:Resonance frequency f0: 10 - 300 kHzSpring constant kC: 0.1 - 50 N/m
Torsion
AFAM Set-Up
Laser diode
Cantilever
Sample
Ultrasonictransducer
Sound wave
Computer
Spectrum
Lock-in-amplifier
Heterodynedown-converter
Signalgenerator
Ultrasonicimage
Reference
Signal
Electricalexcitation
Topo-graphyAFAM
Imaging using AFAM
Topography AFAM image
Area of higher stiffness; It appears as a bright one when imaged at (b) frequency
Soft area: Here one is out of resonance frequency and the amplitude of cantilever vibrations is small
Courtesy by NT-MDT, Zelenograd
Excitation of Contact Resonance Frequencies
AFAM and Ultrasonic Piezomode Images of PTC Samples Annealed at Different Temperatures; Image Size 2 μm x 2 μm.
0.000
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0.008
0.000
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0.008
Silicon
2000 2050 2100 2150 2200 2250 2300
0.07 0.13 0.20 0.34 0.51 0.68 1.02 1.36
Surface amplitude [Å] PIC 151
Frequency [kHz]
Can
tile
ver
vib
ratio
n a
ngle
[ º
]
Contact Resonance Curves, First and Second Mode
0.0000
0.0004
0.0008
0.0012
0.0016
0.0020
0.0000
0.0004
0.0008
0.0012
0.0016
0.0020
0.07 0.14 0.21 0.28 0.36 0.72 1.08
Surface amplitude [Å] Silicon
700 750 800 850
PIC 151
Frequency [kHz]
Can
tile
ver
vib
ratio
n a
ngl
e [ º
]C
antil
ever
vib
ratio
n an
gle
Piezoelectricceramic
Piezoelectricceramic
Silicon Silicon
Transmission of Ultrasound in Macroscopic Experiments:Interface with Mesoscopic Contacts
Frequency f0
Harmonics f0, f1, f2, f3, …
Ultrasonictransducer
Sample withdamagecracksdelaminationsinternal interfaces
• Space Probe
consisting of an orbiter & the landerPHILAE
• Target67P/Churyumov-Gerasimenko
• Time schedule
Start: 2. März 2004
Approach: August 2014
Landing: November 2014
End of mission: December 2014
Rosetta-Mission
Weight on Earth: ~ 830 NWeight on the comet: ~120 mN
Stabilization of the lander on thecomet by a harpoon and icescrews
Three-leg landing-gear each legwith two soles
On the lander there are 10experiments designed to examinethe structure and the compositionof the comet nucleus.
MPAe, Katlenburg-Lindau
≈ 2,50m
15 cm
Philae Landing Gear
• Transmitter and receivers
Piezoelectric transmitters Fraunhofer-Institute for Non-Destructive Testing;Piezoelectric accelerometerBrüel & Kjaer, Naerum, Denmark
• Operation modus
Passive: inactive transmitter Active: active transmitter
CASSE: Cometary Acoustic Surface Sounding Experiment
1. Resolution of imaging determined by wavelength2. Near-field imaging by antenna size
For data reconstruction there are still many things to do
Imaging in Non-Destructive Testing