Imaging of defects with ultrasonic arrays in non canonical ...€¦QNDE 2010, July 21 th, San Diego...

QNDE 2010, July 21th, San Diego

Imaging of defects with ultrasonic arrays Imaging of defects with ultrasonic arrays in non canonical geometriesin non canonical geometries

P. Calmon, S. Robert, S. Bannouf, O. Casula, S. Chat illon

CEA LIST, Saclay


OutlineOutline

� Introduction, context: UT arrays in CIVA

� Full Matrix Capture: 3D imaging, Modelling, Multiple reconstruction

� Imaging of defects through complex surface

� Imaging of defects through complex surface with flexible probes


Context : UT array simulation and processing in CIV A

UT array simulation tools

� Beam computations

� Simulation of flaw responses

� Delay laws computation, ray calculations

� Simulation of sophisticated operating modes: Per channel acquisitions, Full Matrix Capture etc…

Reliable forwards models allowingto address complex situations including reconstruction


For every point P in the sampled ROI , computation of the theoretical time of flight (TOF) applying CIVA forward models

Raw data: Elementary signals

ROI

Extraction on the signalsof the amplitudes at this TOF

ΣΣΣΣ

Mapping the estimator:

E(P) = Σn wnP SnPGeneral form:

wnP = 1FTP:

Principle: A posteriori synthetic focusing

Principle of the Total Focussing Method algorithm

� Coherent summation of the received signals for all the points of the imaged region.

� Identical to SAFT for mechanical scanning.


Shot n°1

Application to Full Matrix Capture acquisitions

Tim

e

Elements (Reception)

Tim

e


Tim

e


Tim

e


Full matrix acquisition :Acquisition of the complete set of signals corresponding to all the T/R pairs

• N successive shots (N: nb of elements)• One shot: 1 transmitting element

All elements receiving

Acquisition of N xN signals:

[ ]NNntSn ×∈ ,1)(


Flat-bottom holes of various height

Full 3D reconstruction and visualization on simulat ed data

Top view

Volumetric rendering with iso-surfaces

« Full Matrix capture » with a 2D matrix array (11 X 1 1 elements, 2MHz)


Matrix probe 16x8 elements - 5 MHz

H = 30 mm

3 notches 120°

h = 5 mm

Top view

3D Total Focussing Method imaging of 3 notches


OutlineOutline


� Full Matrix Capture, 3D imaging, Modelling, Multiple reconstruction




5 mm

30 mm

20 mm

20 mm

5 mm

30 mm

20 mm

20 mm

LL

SimulationExperimental

Calibration: 0db SDH Ø2 mm Traditional imaging Traditional imaging

Applications INDIACMultiple mode reconstruction

FMC acquisitionPhased array : 32 elements, 5MHz

Vertical breaking notchh = 5 mm

ferritic steel

Work supported by : IndiacIndiac project

L

L


5 mm

30 mm

20 mm

20 mm

5 mm

30 mm

20 mm

20 mm

LLL

0dB

LL


-3dB

0dB

Calibration: 0db SDH Ø2 mm

LLL

Applications INDIAC

L

L

L

Multiple mode reconstruction

Traditional imaging Traditional imaging



Imaging of the notch thanks to corner echoes

ferritic steel


New imaging New imaging


5 mm

30 mm

20 mm

20 mm

5 mm

30 mm

20 mm

20 mm

LLL

TTT

+8dB

LL



LLL

TTT


Applications INDIAC

T

T

T






Imaging of the notch thanks to corner echoes

ferritic steel




LL


Nouvelle imagerie Nouvelle imagerie




Vertical non-breaking notchh = 10 mm

ferritic steel




LL

-5dB

-6dB

LLL-1dBL

L

L







ferritic steel


Higher part of the notch not imaged with LLL corner echoes


T

T

T


LL

-5dB

-6dB

TTT +5dB







Higher part of the notch not imaged with TTT corner echoes

ferritic steel





LL

-5dB

-6dB

TTT +5dB


Applications INDIAC

+8dBTLL

L

TL







The notch is totally imaged thanks to TLL mode

ferritic steel



Higher part of the notch not imaged with TTT corner echoes



LL

-5dB

-6dB

TTT +5dB


New imaging

Applications INDIAC

+8dBTLL


New imaging


New imaging



The notch is totally imaged thanks to TLL mode

Map of the number of E-R pairs in condition of reflexion for this notch

ferritic steel


New imaging

L

TL


OutlineOutline






very good detection and localization through

plane and irregular interfaces

Comparison on experimental data


Performance Evaluation by simulationInfluence of unaccuracy on the surface description

With the exact profileh1 = -h2 = 3 mm

- 3dB - 6 dB - 5dB

∆z: 2 mm ∆z: 1 mm∆x: 4 mm

With inexact profiles

∆h1 = + 0.5 mm, ∆h2 = -0.5 mm

- 6dB - 1dB -6dB

∆z: 3 mm ∆z: 4 mm∆x: 4 mm

h1 = -h2 = 2 mm

Ø2mm SDHØ2mm SDH

FMC SimulationLinear array: 64 elts, 2MHz

Lx=100 mm

h2=-3mm

Z(*10)

h1=3mmX

Lx=100 mm

h2=-3mm

Z(*10)

h1=3mmX

Z(*10)

h1=3mmX

Exact profile:


Surface shape reconstruction from immersed array acquisition

Surface

C1 C2

R1R2

x

z

Algorithm:From Time of Flight (TOF)measured on each channel�Profile reconstruction

Functionality implemented in CIVA 10

Export CAD file

From each channel T= R or T≠R

21 ( )

j j j j

j j

x C R R

y R R

′= − ⋅

′= −1

1

j jj

j j

R RR

C C+

+

−′ =

−

Reconstruction


zoom

Exact profile

Reconstructed profile

Surface shape reconstruction

Immersed array 48 elts 5 MHz

Imaging of defects in immersion through complex sur face

error ~ 0.5mm


Imaging of the tilted notch from corner echo

Simulation

TTT

TTL


OutlineOutline






Principle of smart flexible phased array

time

Adapted delay law

focus LW45°

Real time algorithm

Reconstruction Profile

Focal point

global error < 2 % time loop : 1ms

Embedded profilometer

MultiX System (M2M) :

Modification of the settings in real time by embedded processorsReal time Delay law algorithm


14 mm

40 mm27 mm

scanning

Beam steering : LW45 - depth 40mm

Aperture of 24 elements (33 x 17 mm²)

Smart flexible phased array on realistic 2D surface

Focal point

Reconstructed profile


scanning

G3

G3 – Planar surface G7 – Irregular surface-4.0dB

-3.5dB

-2.0dB

0dB (ref)

40mm

0°55°

~4.5mm2 sets of 4 SDH (2mm-diameter) located under:- a flat surface (ref.), - an irregular profile.

Experimental detection of SDH on realistic 2D surfac e

Accurate detection (SNR, Bandwidth)Low sensitivity to surface irregularities (-3.5dB / 5mm)


scanning

LW0° LW0°LW0° 35mm

scanning

Real time reconstruction of external and internal compl ex 2D geometries

Real time visualisation in the M2M software

Profile reconstruction

- Real Time Reconstruction Functionality with the 2D flexible phased-array transducer

�� External surface reconstruction thanks to the embed ded profilometer (error<0.5mm)

�� Internal surface reconstruction with the backwall e cho : Very close to the theory (average error~0.4mm)

- Profile data storage and export to a CAD file form at


LL

TTL LTT


LLT





TLT

FMC acquisitionFlexible probe : 24 elements, 2.25MHz

The notch is imaged thanks to LLT and TLT mode through complex

surface and backwall



Imaging of the tilted notch from corner echo

TTT

TTLRSB = 16 dB

SimulationExperiment

RSB = 14 dB


Matrix arrayElements moulded in a flexible resin

Embedded profilometer

84 elts, 3 MHz

Flat bottom hole (Ø3 mm) at the junction cone/cylinder

3D Imaging: Example of nozzle geometry

Ø 3mm L=10mm depth 40mm


Backwall echo

FBH

Backwall echo

Angular scanning

Scanning

Tim

e

Acquisition

TrajectoryTrajectory : : Scanning along the cone-cylinder junction

AcquisitionAcquisition

3D reconstruction3D reconstruction

3D sectorial scan imaging of the FBH under the juncti on


L-E imageL-H image

E-H image

3D FTP imaging of the FBH under the junction

3D view

L-E Echodynamic

Dynamique: 13 dBRSB 13 dB


SummarySummary

� The reconstruction algorithm Total Focusing Method implemented in CIVA is coupled to forwards models allowing to compute theoretical times of flights in non canonical situations..

� The exploitation of multiple modes offers the means of imaging crack-type defects. Very promising results have been obtained on both simulated and experimental data.

� Comparisons of different acquisition/reconstruction techniques on various cases of interest.

� Optimization of algorithms and strategies for reducing processing time.

In progress:

Conclusions:

Date post:	23-Jun-2018
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Imaging of defects with ultrasonic arrays in non canonical ...€¦QNDE 2010, July 21 th, San Diego...

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