Coherent Adaptive Focusing Technology for the Inspection ... · inspection of variable radiuses, variable opening angles, and twisted components, ... Scalable instruments allows parallel

10th International Symposium on NDT in Aerospace

1 License: https://creativecommons.org/licenses/by-nd/4.0/

Coherent Adaptive Focusing Technology for the Inspection of Variable Geometry

Composite Material

André LAMARRE 1, Etienne GRONDIN 2 1 Olympus Scientific Solutions Americas, Quebec City, Canada

2 Olympus Scientific Solutions of the Americas, Quebec City, Canada

Contact e-mail: [email protected]

Abstract

The aviation industry has seen above normal growth in recent years, owing in part to lower oil prices contributing to millions of dollars in savings for aircraft operators. As a result of this growth, production rates for new airplanes have increased, and new aircraft programs are being launched. Consequently, aviation component manufacturers are facing new challenges, including a rise in production rates, higher probability of detection (POD) requirements due to the critical nature of the parts being manufactured, a lack of skilled operators, and parts with increasingly complex geometry. To respond accordingly, ultrasonic phased array (PA) instruments have evolved, enabling the implementation of advanced acquisition strategies, such as adaptive focusing. Coherent adaptive focusing simplifies the inspection of variable radiuses, variable opening angles, and twisted components, and it also compensates for probe misalignment through innovative signal-processing algorithms. This paper presents an overview of coherent adaptive focusing technology with the goal of helping NDT integrators and composite material manufacturers address system performance, production output, and quality control issues.

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Olympus Scientific Solutions Americas | Andre LAMARRE

Coherent Adaptive Focusing Technology for the Inspection of

Complex Geometry

Introduction

� Ultrasonic Phased-array technology benefits for composite inspection

� Faster inspection

� High-resolution

� Improved coverage

� Different geometries

� Flat and curved parts

� Scalable instruments allows parallel firing of phased-array probes for high productivity

Ultrasonic Phased-array benefits

� Beam forming is produced with pre-determined focals laws(time delays)� Inspection configuration must fit the model used by the calculator (deterministic model)

� Linear array probe must be parallel to the surface of the part to work properly� Probes could be badly positioned (angled)� Flat part might not be perfectly flat (pseudo-flat)

� Curved array probe must be concentric with the radius of the part to work properly� Probes could be badly positioned

� The radius itself could be different from its nominal value� The radius could be a non-perfect radius

� A way to adapt the focal laws(beams) to the real inspection configuration is required:

Ultrasonic phased-array limitations

COHERENT ADAPTIVE FOCUSING

� Adapt the ultrasonic beams(focal laws) to the real inspection scenario

� Improve & simplify the inspection of complex geometry components − Curved and twisted parts − Variable and non perfect radius

� Compatible with− Linear PA Probe on Pseudo Flat Surface− Linear & Curved PA Probe on Radius (inside and outside)

� Performance equivalent to phased array− Inspection speed has to be similar to standard phased array

� Reliable & Robust− No data loss or convergence issues

Coherent Adaptive Focusing (CAF) Objectives

Inspection of Inner radius

� Uncorrect probe positioning:

� Others:

� The radius itself could be different from the nominal value

� The radius could be a non perfect radius

Possible issues with radius inspection

Inner Radius – Out Of Conc. (-) Inner Radius – Out Of Conc. (+) Misalignment

Phased-array inspection of a radius (perfect concentricity)

The distance from the probe to the part must be adjusted so as to coincide the center of radius of the probe to the center of the inner radius of the corner.The entry beams are normal to the radius surfaceLinear scan is performed covering the whole radius

Phased-array inspection of a radius (out of concentricity)

� Part & Scan Parameters

� Geometry: L shape� Radius : 5mm � Out of concentricity : +15mm� Scan : Internal face � Probe : 3.5CC25-32R4

� Wedge : SR4-IE90

Coherent Adaptive Focusing of a radius (out of concentricity) Results

� Out of concentricity : +15mm

Coherent Adaptive Focusing

How does it works?

Coherent Adaptive Focusing

Delay

PA probe

Wave front

Part

FW

BW ?

PA probe

Delay

Part

Wave front

FW

BW

� Adaptive Focusing is an iterative process that allows the transmission of a wave-front parallel to the part

� When achieved, a synthetic linear scan is played off-line to examine the part

n iterations

Coherent Adaptive Focusing – How it works

Step 1:

Acquisition with known Tx – Rx

Element Number

Tim

e o

f Flig

ht (u

s)

Element Number

Tim

e o

f Flig

ht (u

s)

� Step 1 : Acquisition with known delays in Tx and Rx (0 or pre-defined)

Coherent Adaptive Focusing – How it works

� Step 2 : Identification of potential Front Wall Echo location

Step 1:

Acquisition with known Tx – Rx

Step2:

Identify potential FWE

Element Number

Tim

e o

f Flig

ht (u

s)

Coherent Adaptive Focusing – How it works

� Step 3 : Distinguish Artefacts from front wall echo location

Step 1:

Acquisition with known Tx – Rx

Step 2:

Identify potential FWE location

Step 3:

Distinguish Artefacts from FWE

Front WallArtefacts

Element Number

Tim

e o

f Flig

ht (u

s)

� s

Coherent Adaptive Focusing – How it works

� Step 4 : Discard artifacts

Step 1:

Acquisition with known Tx – Rx

Step 2:

Identify potential FWE location

Step 3:

Distinguish artifacts from FWE

Step 4:

Discard artifacts

Element Number

Tim

e o

f Flig

ht (u

s)

Coherent Adaptive Focusing – How it works

� Step 5 : Identify new transmission delays

Step 1:

Acquisition with known Tx – Rx

Step 2:

Identify potential FWE location

Step 3:

Distinguish artifacts from FWE

Step 4:

Discard artifact

Step 5:

Identify new transmission delays

Wavefront Identification

New delay definition Element Number

Tim

e o

f Flig

ht (u

s)

Element Number

Tim

e o

f Flig

ht (u

s)

Coherent Adaptive Focusing – How it works

� Step 6 : Pulse the front wave and run synthetic linear scan off-line to examine the part

Step 1:

Acquisition with known Tx – Rx

Step 2:

Identify potential FWE location

Step 3:

Distinguish artifacts from FWE

Step 4:

Discard artifact

Step 5:

Identify new transmission delays

Step 6:

Front wave and off-linesynthetic linear scan

Element Number

Tim

e o

f Flig

ht (u

s)

Element Number

Tim

e o

f Flig

ht (u

s)

Other configurations results

� Part & Scan Parameters

� Geometry: L shape

� Radius : 0.35 in to 0.5 in.

� Scan : Internal face (ID)

� Probe : 5CC25-32R4

� Wedge : SR4-IE90

� Focus PX hardware

� Focus PC software

� Probe is concentric at the beginning of the scan

Coherent Adaptive Focusing ID inspection with varying radius

Phased-array CAF

Probe is concentric at the beginning of the scan

PA - CAF on ID variable radius 0.35 to 0.60 in.

� Part & Scan Parameters

� Geometry: L shape

� Radius : 0.35 in to 0.5 in.

� Scan :External face (OD)

� Probe : 5CC25-32R4

� Wedge : SR4-IE90

� Focus PX hardware

� Focus PC software

� Probe is concentric at the beginning of the scan

Coherent Adaptive Focusing OD inspection with varying radius

PA - CAF on ID variable radius 0.35 to 0.60 in.

Phased-array CAF

Probe is concentric at the beginning of the scan

� Part & Scan Parameters

� Geometry: flat part

� Water column:

� Probe : 3.5L64-NWI

� Focus PX hardware

� Focus PC software

� Probe is angled 7 degrees

Coherent Adaptive Focusing on flat surface with angled probe

Coherent Adaptive Focusing capabilities

Coherent Adaptive Focusing Solution Results

� Boundaries

Name Results

Maximum Out Of Concentricity

(+) 30.0 mm(-) 2.0 mm

Maximum Misalignment Horizontal

(±) 6.0 mm

Maximum Misalignment Vertical

(±) 6.0 mm

Coverage 90.0°

Detection (Reliability & Stability)

All flaws detected &

no data loss

Name Results

Maximum Out Of Concentricity

(+) 9.5mm(-) 10.0mm*

Maximum Misalignment Horizontal

(±) 6mm

Maximum Misalignment Vertical

(±) 6mm

Coverage 90.0°

Detection (Reliability & Stability)

All flaws detected &

no data loss

Name Results

Maximum tilt 25.0 °

Coverage @Max. tilt

d = L*cos(alpha)d: coverageL: probe lengthalpha: tilt angle

Detection (Reliability & Stability)

All flaws detected &

no data loss

Case 1 : Inner Radius Inspection Case 2 : Outer Radius Inspection

* Until the probe touches the part

Case 3 : Tilted Probe/Part

Coherent Adaptive Focusing Solution Results

� Productivity

Parameters

Nb. Of Elements 32

Aperture Size 4

Aperture Steps 1

Water path 25 mm

Material Thickness 8.5 mm

Material Velocity 2700 m\s

Nb. Of iterations 5

PRF with CAF PRF without CAF

300 Hz* 517 Hz

FPGA implementation should result in a PRF improvement of up to 450 Hz

Conclusions

� Allows to adapt the beams(focal laws) to the real inspection configurations

� Relaxes the need on mechanics to be perfectly aligned

� Is compatible with linear and curved phased-array probes

� Ease the inspection of components with changing configurations (varying radius, varyingaperture, pseudo-flat…)

� Has detection and speed performances comparable to phased-array

� Easy to use by operator

Coherent Adaptive Focusing