development of an advanced ultrasonic phased array for the

Development of an advanced ultrasonic phased array

for the characterization of thick, reinforced concrete

components

Laurence Jacobs, Georgia Institute of Technology

Kim Kurtis, Jin-Yeon Kim, Prasanth Alapati, Max May (Georgia Tech)

Jianmin Qu, Xiang Gao (Tufts University)

Develop ultrasonic phased array device that uses wave mixing and

nonlinear acoustic techniques to quantitatively characterize and image

microscale (100 μm) damage in thick, reinforced concrete components.Total Project Cost: $0.87M

Length 24 mo.

Project Vision

The Concept

‣ Increase concrete durability by developing an ultrasonic phased array device to

characterize and quantify microscale damage throughout component thickness

‣ Combine ultrasonic phased array technology with nonlinear wave mixing and

concrete material modeling to enable “medical quality” imaging of reinforced

concrete components

The Team

‣ Team of four faculty co-PIs from Georgia Tech (3) and Tufts University (1)

‣ Laurence Jacobs: linear and nonlinear ultrasound, NDE of concrete

‣ Kim Kurtis: emerging and novel methods to understand cement based materials

‣ Jin-Yeon Kim: measurement and modeling methods for NDE, phased arrays

‣ Jianmin Qu: ultrasound and micromechanics of concrete

‣ Jacobs and Kim: development of the phased array device; material modeling

‣Qu: computational modeling to optimize wave mixing scheme

‣ Kurtis: material modeling and development of specimens with known damage

2

Project Objectives

‣ First three quarters: computationally demonstrate and optimize wave mixing

conditions and physically demonstrate capability to generate forward mixed wave

with phased array and array (antennae) sensors

‣ First year go/no-go demonstration of forward wave mixing to detect and

characterize microscale (on the order of 1.0 mm) damage in 3-D with a scan time

under 30 minutes for a volume of 500 cubic inches for forward propagation

(10/15/2020)

‣ Team will develop and commercialize phased array capable of nonlinear wave

mixing in the 10-100 kHz range

‣Working to identify the best first commercial applications: where is an image of

microscale damage through the thickness critical to inform and prioritize

maintenance and repair strategies?

3

Motivation: Nonlinear Rayleigh waves to track ASR damage

‣ Application of nonlinear Rayleigh surface waves to

characterize ASR damage (Previous work by team)

‣Measurements on both EPRI slabs and ORNL/UTK slabs

4

Kim et al, JNDE 2017 and Con Bldg Mat, 2018

Motivation: Wave mixing fundamentals

( , ) cos[ ( )]R R

T

yu y t A t

c

2

0 0 0( ) ( ) ( )

2 ( )

T T

T L T

y U y V y lA

c c c

Resonant

Shear Wave L TR T

L T

c c

c c

Vl

Vs_new

Thickness d

Lo

ng

itu

din

al

wav

e

tra

nsd

uce

r

Received

signal

Vs

y,vx,u

Sh

ear

wa

ve

tra

nsd

uce

r

2L L

T L T

c

c c

Resonant

Condition

y0

( , )Lu y t( , )Tu y t

( , )Ru y t

6

Out-of-plane polarization:

In-plane polarization:

2cos Δ𝜃 2− 1 = cos(2Δ𝜃)

Model for wave mixing: Polarization analysis

Model for wave mixing: Beam steering with an array

• Typical side lobes with peak side lobes

much smaller than main lobe

• Phased arrays are designed for fixed

frequency, nonlinear wave mixing

techniques with varying frequencies would

add additional design constraints

• Array for beam steering only, not detection

• Normalized pressure for beam steering at 𝜃_𝑠=30°, with parameters: 𝛿_𝑥=25𝑚𝑚, 𝑁=8,

𝑓=80𝑘𝐻𝑧, 𝑐_𝑇=2702 𝑚𝑠^(−1), 𝜆_𝑙=3.38𝑐𝑚

• Main lobe at 30°

• Grating lobe appears due to spatial aliasing

for 𝜆_𝑙/2<𝛿_𝑥 at −58°

7

Model for wave mixing: Maximum steering angle 𝜃𝑠8

• Steering angles of both arrays are limited depedent on their

input frequency

• Frequency ratio is fixed by condition at mixing points

• Lower frequencies degrade steering ability

Model for wave mixing: Possible configurations

Traditional configuration Arrays on wedges

9

11/6/2020

Computational results: Amplitude of mixing wave at receiver

𝐿 = 𝜉ℎ

h

1 2

Array Transducer #1 Array Transducer #2

Signal Receiver

𝜙

Δ𝜃𝑑1 𝑑2

𝑑3

21 21 2 1 2 1 1 2 2 3 32

( ) cos 1 exp( )T T

L

U UA d d d

C

Amplitude with attenuation

2

2

1 2

1 1 1 2 3 2cos( ) 1 , ,

2T T

m m

Frequency(MHz) Attenuation (dB)

0.1 73.2

0.08 58.5

0.05 36.6

0.03 22

0.01 7.3

0:00:14/9:49

Computational results: Polarization choices

Resonant mixed waves cos 1 2

1 2( ) ( ) ( )SV SV L 2

11 cos2

1 1

1 1

1 2( ) ( ) ( )SH SH L 2

11 cos2

1 1

1 1

1 2( ) ( ) ( )L SV L 1

1 cos

1

2

1k

2k

1 2

k k k

1 2

k k k

2L Tc c

SV – Transversely Polarized Shear Wave

SH – Horizontally Polarized Shear Wave

L – Longitudinal Wavec k

11/6/2020

Computational results: Effects of attenuation

1 2 1 2( ) ( ) ( )SV SV L

dB

Measurement results: Array equipment

13

Array Antennae

(32 elements x2)

Array

Controller

Possible setup on concrete slabUltrasonic array system

Surrogate Concrete Slab

Interface

Cables

Measurement results: Samples

14Insert Presentation NameNovember 6, 2020

Samples: mini mortar and concrete blocks 15x15x40 cm^3

Concrete

Mortar

Array Antennae

Measurement results: Single-sided inspection using the reflection of the

mixed wave off the bottom surface

Is the amplitude of the nonlinear mixed signal

large enough to be detected after reflection from

the bottom surface?

Primary wave

Secondary wave

Phased Array 1 Phased Array 2

Non-contact receiver

Primary wave

Concrete block

A

B

Inspection volume

Detect reflection of mixed wave off of

the bottom surface

Bottom Surface

1

23

4

Changing the

separation

distance

between

transducers.

Measurement results: Reference mixing in the mini concrete block

@ spot #3 (10 cm from the top surface)

Multiply reflected signals

Window where the

nonlinear mixing

signal is expected,

based on time of

flight

Signal processing

(windowing, band-pass filtering)

Frequency Spectrum

Filtered

nonlinear mixing signal

Bounce mixed ultrasonic signal off bottom surface for single side operation

Original


Expected


0

12″

Cross section at

AA1

4″

5″

4.5″

12″

Recycled

aggregate

3″4.5″

Cross section at

AA1

4″

5″

4.5″

12″

ASR

3″4.5″

Cross section at

CC1

4″

5″

4.5″

Entrained

air voids

3″4.5″

Cross section at

DD1

4″

5″

4.5″

Fire

damage

3″4.5″

12″ 12″

Mechanical

damage

Thermal

damage

5 ft

12″

Recycled

aggregate

A

A1

3″4″

4″

5″

B

B1

3″4″

4″

5″

6″

C

C1

3″4″

4″

5″

D

D1

1-3″4″

4″

5″

6″ 14″6″

ASREntrained

air voids Fire

damage

Mechanical

damage

12″Thermal

Measurement results: Sketch of the concrete block showing 4 types of embedded

microscale damage

19

Challenges

‣ One challenge is the inherent physics of the problem: high attenuation due to

scattering from the aggregate and material interfaces in the ultrasonic frequency

range

‣ A second challenge is lack of array (antennae) manufacturers in the required

frequency range: this application is too low for medical (and metallic material)

applications, and too high for near field geophysics applications

‣ A third challenge will be that many owners take the “ignorance is bliss” approach.

‣Wave mixing and nonlinear ultrasound allow for a lower frequency approach and

still enable imaging at the microscale level

‣Once the device has been developed and its accuracy demonstrated, it will be

critical to find the right field demonstration application

Potential Partnerships

‣ Team with concrete NDT suppliers. EPRI and Georgia DOT. Any capabilities to

offer other teams, or potential collaborations with other teams?


Summary Slide

‣ Combine ultrasonic phased array technology with an understanding of nonlinear

wave propagation in heterogeneous media and concrete material modeling to

enable “medical quality” imaging and characterization of thick reinforced concrete

components

‣ Nonlinear mixing techniques are not wavelength dependent, thus enabling

characterization of microscale damage (much smaller than inherent

microstructure) in heterogenous concrete material

‣ Team has expertise NDE of concrete, nonlinear wave mixing, phased arrays and

material modeling of concrete

‣ Develop ultrasonic phased array device that uses wave mixing and nonlinear

acoustic techniques to quantitatively characterize microscale damage in thick,

reinforced concrete components


23

Spares

24

Project Vision

0:00:14/9:49

Computational results: Choices of incident wave pairs

1k

2k

1 2

k k k

1 2

k k k

Forward Mixing

Backwards Mixing

1 1 c k

2 2 c k

1 2 c k k

1 2 c k k

11/6/2020

Computational results: Choices of incident wave pairs

development of an advanced ultrasonic phased array for the

Documents