8/26/19 1

Unlocking New Applications w/ PAUT Transducers

Steve Strachan – Sensor Networks, Inc.8/21/2019

AgendaPhased Array vs. Conventional UT Overview

Types of Phased Array UT Transducers

Phased Array UT Transducer Manufacturing• Development• Design• Prototype• Manufacture

Applications for Phased Array UT Transducers

Conclusion

Phased Array vs. Conventional UTQue es?: Using multiple channels of ultrasound (instead of a single channel) to be able to detect, measure, and image anomalies in a specimen under evaluation

Como funciona?: Using high end portable or stationary equipment capable of firing multiple channels of ultrasound

Por que?: • Increased POD (Probability of Detection)• Image and measurement capability• Speed at which one can inspect• Larger area inspection ability• Ability to more easily inspect complex

geometries & materials

Phased Array vs. Conventional UT

Conventional UT Equipment & Data Phased Array UT Equipment & Data

Phased Array vs. Conventional UT PROBES

Conventional UT Probes ($150-$3,000) Phased Array Probes ($3,000-$80,000)

How does Phased Array UT Work?

How does Phased Array UT Work?

Different Phased Array Types

Phased Array Nomenclature

Key Points• Big Aperture to

focus deep• Small elements

to steer far

How to BUILD a Phased Array UT Transducer?

https://www.youtube.com/watch?v=jkVTafD-e98

Transducer Story … in real life!

Incident: April 18, 2018 a critical failure of a Boeing 737 engine on Southwest Airlines flight number 1380 forced an emergency landing, in New York LaGuardia airport where multiple people were injured and a woman was killed.

https://abcnews.go.com/US/plane-makes-emergency-landing-philadelphia/story?id=54530003

Problem Statement

Root Cause: Stage 1 fan blade developed a fatigue crack which resulted in loss of containment (ejected blade)

Solution Requirements: Need inspection method to test existing fleet of engine blades in the field as accurately as possible as QUICKLY AS POSSIBLE

The Solution …

Fracture Mechanics Analysis: Engine manufacturer able to duplicate incident

Samples Manufactured: Had EDM notches put into new specimen to mimic fatigue crack, sent to SNI to have modeled, designed, and prototyped

The Solution …

UT Beam Modeling Computer Aided Design for Transducer

The Solution …

PAUT – TFM/FMC ... Great Technology …

Total Focusing Method or Total Electronic Focusing (TFM): electronic focusing which consists of adapting the receiving delay laws to focus at many points which form a grid, after a single pulse which generates a large and/or divergent ultrasonic beam

Full Matrix Capture (FMC): FMC specific data-acquisition process using ultrasonic array probes where each element in an array is successively used as the transmitter, while all elements are used as receivers for each transmitted pulse

PAUT – TFM/FMC ... But it’s all about the Probe!

Advantages of TFM/FMC:• Optimal focusing and spatial

resolution everywhere• Direct imaging of a large area

for one probe position• All reachable angles with the

array simultaneously• Defect characterization• Comprehensive imaging of

defect• 3D imaging

Element Steering

Depth/Focusing

Element Spacing

Frequency

PAUT – TFM/FMC & HTHA

High Temperature Hydrogen Attack (HTHA):• Petrochemical industry inspection

application• Characterization of stress or

corroded areas in hydrogen service above 200C in carbon steel assets

• Until now, probability of detection was <1%

• Today utilizing TFM/FMC & high end PAUT transducers, POD has increased to >10% DLA 10 MHz Probe: Pitch & Catch PA

64E w/ small pitch used in LW mode for improved TFM imaging

AL-TFM 5 MHz Probe: Pulse Echo PA 64E with small pitch used in SW mode for improved TFM imaging in HAZ under weld cap

Phased Array Nuclear Bolt Inspection

Overview:• Segmented-Annual Array• 360 degree electronic scanning• Displaced manual & motorized

scanning

Custom Phased Array Transducers

Custom Phased Arrays:• Nasa• Composite Backscatter• 253 discrete .125” transducers• 4.5” Radius• 10 MHz Alpha Transducers• Complex 5-Axis CNC Milling• Compound-radius Wedges• $80K selling price

Designing the New … Improving the Old …

Strain Relief: The most common failure of Phased Array transducers is undoubtedly the strain relief • Lasts @ 550K vs. 50K

cycles• Improve lifespan of

transducers by 10x

Designing the New … Improving the Old …

Low-Noise Wedges: Investing R&D into new noise-dampening material w/ similar acoustic impedance as the wedge itself• Increased Signal-to-Noise • Highly attenuative• Radiused for OD, ID, or other

complex radii exams

Conclusion

Understanding when to use conventional UT vs. Phased Array

Phased Array UT Transducers come in all different shapes, sizes, and configurations …

Select the RIGHT PROBE for the job

Custom solutions are being built all the time … test the boundaries!

Thank You!

Sources:• https://www.olympus-ims.com/en/• https://www.aos-ndt.com/product/fmc-tfm/• https://www.m2m-ndt.com/en/technology/pa-

techniques/total-focusing-method-tfm/• https://www.slideshare.net/ZetecNDT/principles-of-full-

matrix-capture-fmc-and-total-focusing-method-tfm-in-ultrasonic-inspections

strachan@sensornetworksinc.com