Method and system of deducing sound velocity using time-of-flight of surface wave

Patent metadata

Field	Value
Publication number	US-10309934-B2
Application number	US-201715472449-A
Country	US
Kind code	B2
Filing date	Mar 29, 2017
Priority date	Mar 29, 2017
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

Disclosed is an ultrasonic non-destructive testing and inspection system and method for determining acoustic velocities in a test object. Beams of acoustic energy from firing an element of an emitting probe propagate in a first wedge, and a beam incident at the critical angle generates a surface wave in the test object. The surface wave propagates to a second wedge and signals are received at receiving elements of a receiving probe array. When a set of appropriate delays is applied to the receiving elements, the acoustic time-of-flight is the same to all receiving elements. Determination of the appropriate delays and the times-of-flight for P-type surface waves and Rayleigh surface waves enables computation of the P- and S-wave acoustic velocities in the test object. The time-of-flight measurement also enables computation of the separation between the first and second wedges.

First claim

What is claimed is:

1. A method of determining ultrasonic velocity in a test object using an ultrasonic measurement system, the system having an emitting probe operable with an emitting wedge and a receiving probe operable with a receiving wedge, the wedges configured to be in contact with a test surface of the test object, wherein the receiving probe is an array probe having a number N of receiving elements, the receiving elements designated element (n) for n=1 to N, the method comprising the steps of:
obtaining known parameters for the probes and the wedges;
firing at least one emitting element of the emitting probe, thereby causing the at least one emitting element to emit beams of ultrasonic energy into the emitting wedge, including a critical beam at a critical angle which generates a surface wave of ultrasonic energy propagating near the test surface in the test object towards the receiving wedge;
receiving corresponding A-scans from each element (n) of the receiving probe, the A-scans comprising amplitudes of received echo signals as a function of arrival times at each element (n); and,
determining at least one surface wave velocity of the surface wave, and,
wherein the known parameters comprise the number N of the receiving elements, a pitch p, wherein p is the distance between adjacent receiving elements, an emitting wedge angle θ w ′ of the emitting wedge, a receiving wedge angle θ w of the receiving wedge, and a wedge velocity V w , wherein V w is the velocity of longitudinal waves in the receiving wedge.

2. The method of claim 1 wherein the at least one surface wave velocity is a longitudinal wave (P-wave) velocity V P of a P-type surface wave.

3. The method of claim 1 wherein the at least one surface wave velocity is a longitudinal wave (P-wave) velocity V P of a P-type surface wave and a Rayleigh wave velocity V R of a Rayleigh surface wave.

4. The method of claim 3 further comprising the step of calculating a shear wave (S-wave) velocity V S in the test object based on the P-wave velocity and the Rayleigh wave velocity.

5. The method of claim 4 wherein the step of calculating the S-wave velocity further comprises the step of calculating the S-wave velocity V S in accordance with the following equation

(

2
-

v
R
2

v
S
2

)

2

-

4
*

(

1
-

v
R
2

v
P
2

)

1
2

*

(

1
-

v
R
2

v
S
2

)

1
2

=
0.

6. The method of claim 3 wherein the receiving wedge angle is zero, and wherein the calculated P-wave velocity V P and the calculated Raleigh wave velocity V R are independent of the wedge velocity V W .

7. The method of claim 3 further including the steps of:
defining a P-wave region of interest in each of the A-scans, the P-wave region of interest corresponding to approximate P-wave arrival times of P-wave signals generated by the P-type surface wave and being based on at least one nominal P-wave mode property;
finding a set of P-wave reception delays to be applied to each element (n), wherein, after application of the P-wave reception delays, P-wave time-of-flight measurements from the at least one emitting element of the emitting probe to each element (n) of the receiving probe are equal to a constant P-wave time-of-flight τ P for all n from 1 to N; and,
calculating the P-wave velocity from the set of P-wave reception delays and the known parameters.

8. The method of claim 7 wherein the at least one nominal P-wave mode property is that the P-type surface wave has a high acoustic velocity and comprises earliest received echo signals in the A-scans.

9. The method of claim 7 wherein the set of P-wave reception delays comprises P-wave reception delays which vary linearly as a function of n, and a n th P-wave reception delay is equal to ε P *n wherein ε P is a constant, and wherein the step of calculating the P-wave velocity comprises calculating the P-wave velocity V P in accordance with the following equation

ɛ
P

=

p

v
w

*

(

sin
⁢

⁢

θ
w

*

1
-

(

v
w

v
P

)

2

-

(

v

Assignees

• Bruett Cecile
• Painchaud April Guillaume
• Kwan Chi Hang
• Lepage Benoit
• Olympus Scient Solutions Americas Inc

Inventors

• Brütt Cécile
• Painchaud-April Guillaume
• Kwan Chi-Hang
• Lepage Benoit

Classifications

• G01N29/262

  by electronic orientation or focusing, e.g. with phased arrays (phased arrays per se G10K11/34) · CPC title

• G01N29/07 Primary

  by measuring propagation velocity or propagation time of acoustic waves · CPC title

• G01N2291/0423

  Surface waves, e.g. Rayleigh waves, Love waves · CPC title

• G01N2291/102

  one emitter, one receiver · CPC title

• G01N29/30

  Arrangements for calibrating or comparing, e.g. with standard objects · CPC title