fmc/tfm - aroend.ro
TRANSCRIPT
FMC/TFM
Choosing the right probe and propagation path
Olympus Canada - Chi-Hang Kwan
Namicon – Octav Teodorescu
Olympus Europa - Florin Turcu
01 Introduction
02 Total Focusing Method
03 Choice of probe and propagation modes
04 Solution: A.R.O.I.
05 Experimental validation
06 Conclusions
07 References
01 Introduction
TFM/FMC
Page 4
FMC – Full Matrix Capture and TFM – Total Focusing Method
Ultrasound Imaging Technique with a high potential for
▪ Improved sensitivity
▪ Wider field of view
▪ True-to-geometry view
▪ Potentially improved probability of detection (POD)
Phased Array – has its roots in single-element conventional ultrasound;
TFM – can be seen as next step in industrial Ultrasound imaging following PA
• Complexity – requires guidance and standards of practice to consider:
• Choice of probe/wedge combination
• Selection of mode and propagation path
02 Total Focusing Method
TFM/FMC – the basics
Page 6
FMC – Full Matrix Capture and TFM – Total Focusing Method
– Total Focusing Method (TFM) is an advanced data processing algorithm.
▪ AQUISITION
– Data is usually acquired using the FMC (Full Matrix Capture) method.
▪ FOCUSING
– When applied to ultrasound data acquired with a multi-channel instrument, it allows focusing the acoustic energy in all
points of a given region of interest.
▪ IMAGE:
– The result is a high resolution image of the zone of interest
FMC/TFM – How it works
It all starts withConventional UT
UT
Acoustics
Near field/ far field zones
Beam spread
Mode conversion – Snell/Descartes Law
ALL is still valid and MUST be taken into account
when using/performing TFM
Going ThroughBasic Phased-Array
PAUT
Page 10
S
Signals coming from the reflector
arrives at first on the closest element
Signals coming from the reflector
finally arrives on the furthest elements
Appropriate delays
are electronically
introduced during
reception
Only signals “satisfying” delay law shall
be “in phase” and generate significant
signal after summation
How Phased-array work ?▪ DELAYS: Appropriate delays are introduced electronically during emission and reception
▪ SUMMATION: Only signals “satisfying” delay law shall be “in phase” and generate significant signal after summation
And nowFMC – Full Matrix Capture1st step
FMC = Full Matrix Capture
Pulse on 1st element, receive on all
Pulse on 2nd element, receive on all
Pulse on 3rd element, receive on all
….
A complete « MATRIX » is built
generating a huge amount of data.
FMC Probe elements
. . .
Acquisition matrix.
Each matrix element stores one A-scan
Repeat 1 million times
Result: 1 million matrices 32x32 A-scans
TFM = Total Focusing Method2nd step
TFM Techniques
TFM = Total Focusing Method = data processing
An image is processed
Each pixel is treated as a focal point
The algorithm used to image this data is generated
through a standard sum and beam-forming approach
Other algorithms possible
S
S
Transmitter 1
S
Transmitter 2
Transmitter 32
FMC
TFMLine 1
Line 2
Line 32
Zone of
interest
A-scans saved in each line
of the FMC matrix
Delays applied for
synthetic focusing in
reception phase
Delays applied for
synthetic focusing in
transmission phase
summation summation
Resulted focused data in
one image point
Page 16
To obtain an image
03 Modes of Propagation
The operator needs to indicate the chosen Mode and Path depending on application
Direct Paths 4 possibilities
TT, LL, TL, LT
Modes of Propagation
Where:
T → Transverse / Shear Wave
L → Longitudinal / Pressure WaveLL TT
TTTTLL
LL
TT LL
TL LT
Indirect Paths (or pitch-catch / or half-skips) 8 possibilities
LLL, LLT, LTL, LTT,
TLL, TLT, TTL, TTT
Modes of Propagation
L
L
L
L
L
T
T
T
TT
T
T
Remember Snell (Descartes) law:
– the higher the velocity, the larger the reflection / refraction angle
Mode Conversions
𝑆𝑖𝑛 ∅𝑖𝐿
𝑐𝐿1=𝑆𝑖𝑛 ∅𝑅𝐿
𝑐𝐿1=
𝑆𝑖𝑛 ∅𝑅𝑇
𝑐𝑇1=𝑆𝑖𝑛 ∅𝑟𝐿
𝑐𝐿2=𝑆𝑖𝑛 ∅𝑟𝑇
𝑐𝑇2
Mode Conversions
T
LL
T
T
L
▪How do we use it?
Remember Snell (Descartes) law:
– the higher the velocity, the larger the reflection / refraction angle
Mode Converted Paths (or Full-Skips) 16 possibilities
LLLL, LLLT, LLTL, LLTT,
TTLL, TTLT, TTTL, TTTT , etc…
Modes of Propagation - complexity
Note: Not all modes are useful in
practice for common applications.
Most Common Modes
1. Direct: TT, LL
2. Half-Skip: LLL, TTT, LTT, TLT, TLL
3. Full-Skip: TTTT, LLLL
1
2
3
Modes - example
TT mode
Modes - example
TTT mode
04 Solution: A.R.O.I
Page 27
Addressing complexity AROI
▪ Olympus developed and patented a unique TFM scan plan method
▪ AROI – Acoustic Region of Influence
TTT
Page 28
Addressing complexity AROI
▪ Analytical – simulation method of acoustic field
▪ Implements basic acoustic formulas: reflection, refraction, beam spread, near field etc
▪ Does not require computing power
TTT
Page 29
Addressing complexity AROI
▪ Image depends on:
– Probe and wedge
– Wave mode
– Sound Path
– Reflector type: volumetric or planar/ flat
– Reflector orientation (if planar)
TTT
05 Experimental validation: choice of
probe, mode and path
Page 31
Resolution block▪ Different aperture
▪ Different pitch
▪ Different frequency
Low frequency/ small pitch HIGH frequency/ small pitch Low frequency/ large pitch and
aperture
Good resolution and sensitivity near surface Good resolution and sensitivity middle zone Good resolution and sensitivity middle and distant zone
Page 32
5L64-A32 – pitch 0.5, aperture 32mm 5L64-NW1 – pitch 1, aperture 64mm
a) b) c)
d)e)
Corrosion - Pitting
▪ Different aperture
▪ Different pitch
Small pitch and aperture Larger pitch / wider aperture
Better directionality / small coverageWorse directionality / larger coverage
Page 33
T
T
T
T
L
T
T
L
a)b)
Weld - CrackSub-surface Back-wall
▪ Different modes
▪ Different path
Page 34
TT TT – 10MHz
TT TT – 5MHz
Weld – lack of fusion▪ Different frequency
06 Conclusions
Conclusions
Page 36
▪TFM – new technique with a lot of potential in corrosion and weld applications
▪High complexity, but high potential for being miss-used
▪AROI – Acoustic Region of Influence
– Can help the operator chose the right parameters vs application
– An excellent tool for learning
– Light algorithm – no Finite Element Simulation
07 References
References
Page 38
▪ [1] C. Holmes, B. W. Drinkwater, and P. D. Wilcox, “Post-processing of the full matrix of ultrasonic transmit–receive array
data for non-destructive evaluation,” NDT E Int., vol. 38, no. 8, pp. 701–711, Dec. 2005.
▪ [2] K. Sy, P. Bredif, E. Iakovleva, O. Roy, and D. Lesselier, “Development of methods for the analysis of multi-mode TFM
images,” J. Phys. Conf. Ser., vol. 1017, p. 012005, May 2018.
▪ [3] Chi-Hang Kwan, Guillaume Painchaud-April, Benoit Lepage, TFM Acoustic Region of Influence, ASNT Spring Research
Symposium
▪ [4] Olympus, Phased Array Probe catalogue
Test Overview
Test Block EP1000-PABLOCK-1 Phased Array
Aluminium Demo Block with 5L64A32 and
SA32-N55S-IHC
Page 39
Results
Page 40
LLL TTT
LTTTT
Results
Page 41
LLL TTT
LTTTT
Results
Page 42
LLL TTT
LTTTT
Results
Page 43
LLL TTT
LTTTT
Results
Page 44
LLL TTT
LTTTT
Results
Page 45
LLL TTT
LTTTT
Results
Page 46
LLL TTT
LTTTT
Results
Page 47
LLL TTT
LTTTT
MX2 & SX Updated 2019 MXU 4.4R4 !
Page 48
MX2:
▪ Multi-Group inspection
▪ Modularity for changing needs
SX:
Single group inspection
Small
Simple
Still an OmniScan
MX1New electronics updated in 2018 to be CE certified & ROHS compliant
ECA & ECT Modules
BondTesting C-scan
Page 49
ADVANCED ULTRASONIC TECHNIQUES TRAINING & WORKSHOP
Page 50
- Phased Array
- TOFD
- TFM / FMC
- Basic & Physics
- Scan Plan & Acquisition & Analysis
- Applications
- Hands-on & Practice
- Q & A
- Conclusions
METHODS:
CONTENT:
WORKSHOP:
Grand Hotel Phoenicia – Bucharest September 2019