Device for measuring bulk stress via insonification and method of use therefor

• US 20080236285A1
• Filed: 03/27/2007
• Published: 10/02/2008
• Est. Priority Date: 03/27/2007
• Status: Active Grant

• Current Assignee: John M. Carlyle, Michael K. Mcinerney, Sean W. Morefield, Victor H. Kelly, Vincent F. Hock
• Original Assignee: John M. Carlyle, Michael K. Mcinerney, Sean W. Morefield, Victor H. Kelly, Vincent F. Hock
• Inventors: Hock, Vincent F., Morefield, Sean W., Carlyle, John M., Kelly, Victor H., McInerney, Michael K.
• Granted Patent: US 7,614,303 B2
• Time in Patent Office: Days
• US Class Current: 73/597
• CPC Class Codes: G01H 5/00 Measuring propagation velocity of ultrasonic, sonic or infrasonic waves , e.g. of pressure waves
• CPC Class Codes: G01N 2291/048 Transmission, i.e. analysed material between transmitter and receiver
• CPC Class Codes: G01N 29/07 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 29/223 Supports, positioning or alignment in fixed situation mounting transducers per se G10K11/004
• CPC Class Codes: G01N 29/4409 by comparison

Abstract

A device and method to nondestructively measure bulk stress in a member by employing an acoustic source, preferably an ultrasonic source, a processor, and a uniquely configured acoustic sensor package. The sensor package is configured to transmit both a longitudinal wave signal and a shear wave signal into the member. The processor is configured to capture reflections of the two impressed signals along a principal stress axis of the member and calculate the roundtrip time of the two signals. Knowing the length of the member along a principal stress axis, from the roundtrip times of the two signals, two velocities are calculated. By employing an equation that calculates bulk stress as a function of these shear and longitudinal wave velocities, a measure of bulk stress is calculated via the processor. The device measures bulk stress of a member that offers limited access in its permanent installation, such as dam reinforcements.

Claims

1. A method for obtaining a measure of bulk stress in an object, comprising:

establishing the length of said object along a first axis of interest, said first axis having a proximal and distal end;

providing at least one sensor package having a proximal and distal end, said sensor package having at least one each first and second elements, at least one each first and second connectors positioned on said proximal end, said first connector in operable communication with said first element and said second connector in operable communication with said second element,

wherein said first element facilitates communicating at least one acoustic signal in the form of a shear wave, and

wherein said second element facilitates communicating at least one acoustic signal in the form of a longitudinal wave;

coating at least part of said distal end of said sensor with shear gel;

bringing said distal end of said sensor package into contact with said object;

producing internally at least first and second electromagnetic signals for conversion to first and second acoustic signals;

applying said first electromagnetic signal to said first connector to transmit said first acoustic signal out of said first element;

receiving at least one first reflection of said first acoustic signal from said distal end of said first axis; and

establishing the elapsed time from initial transmission of said first acoustic signals at said sensor to receipt of said first reflections at said sensor;

processing said elapsed time with said established length of said object to yield at least one first estimate, V_s, of the velocity of said first acoustic signals in said object;

applying said second electromagnetic signal to said second connector to transmit said second acoustic signal via said second element;

receiving at least one second reflection of said second acoustic signal from said distal end of said first axis;

establishing the elapsed time from initial transmission of said second acoustic signals at said sensor to receipt of said second reflections at said sensor;

processing said elapsed time with said established length of said object to yield at least one second estimate, V_l, of the velocity of said second acoustic signals in said object; and

employing one value each of V_l and V_s in an algorithm, deriving said measure of bulk stress.

2. The method of claim 1 providing said sensor package in a housing having a proximal and distal end, said connectors provided through an external surface of said proximal end of said housing and said distal end of said housing configured such that said sensors may contact said object and transmit said acoustic signals into said object.

3. The method of claim 2 providing said acoustic signal as an ultrasonic signal.

4. The method of claim 1 providing said first element as a solid cylinder concentric with a longitudinal axis of said sensor package and providing said second element as a hollow cylinder of wall thickness, t, arranged concentrically about said first element, wherein t is approximately equal to the radius, r, of said first element.

5. The method of claim 1 providing said algorithm employing the relationship:

$\mathrm{\sigma <br><br>}=\frac{\left(V_l^2-2<br><br>V_s^2\right)}{2<br><br>\left(V_l^2-V_s^2\right)}$

wherein σ

is said measure of bulk stress along said first axis of said object.

6. The method of claim 1 establishing said first axis of said object as the principal stress axis of said object.

7. A device for obtaining a measure of bulk stress along a first axis of an object, comprising:

at least one sensor package having a proximal and a distal end, said sensor package having at least one each first and second elements and at least one each first and second connectors, said first and second connectors positioned on said proximal end, said first connector in operable communication with said first element and said second connector in operable communication with said second element,

wherein said first element facilitates communicating at least one acoustic signal in the form of a shear wave, and

wherein said second element facilitates communicating at least one acoustic signal in the form of a longitudinal wave;

shear gel;

wherein said shear gel is coated on at least part of said distal end of said sensor or said object at point of contact of said sensor package with said object;

at least one source of acoustic signals,

wherein said source produces at least first and second acoustic signals;

at least one processor for processing said signals and reflections thereof from said distal end of said first axis of said object; and

at least one algorithm, said algorithm employing one value each of the velocities, V_s and V_l, of said signals from said first and second elements, respectively,

wherein processing said algorithm provides said measure of bulk stress.

8. The device of claim 7 in which said sensor package is incorporated in a housing having a proximal and distal end,

wherein said connectors are provided through an external surface of said proximal end of said housing, and

wherein said distal end of said housing is configured to transmit said acoustic signals when facilitated by a coating of said shear gel.

9. The device of claim 8 in which said housing is a cylinder having said elements epoxied to a wear plate to facilitate the conduction of acoustic waves and particularly said shear wave between said elements and said wear plate that contacts said object via said shear gel.

10. The device of claim 7 in which said first element is a solid cylinder concentric with a longitudinal axis of said sensor package and said second element is a hollow cylinder of wall thickness, t, arranged concentrically about said first element,

wherein t is approximately equal to the radius, r, of said first element.

11. The device of claim 7 in which said algorithm employs the relationship:

$\mathrm{\sigma <br><br>}=\frac{\left(V_l^2-2<br><br>V_s^2\right)}{2<br><br>\left(V_l^2-V_s^2\right)}$

wherein σ

is said measure of bulk stress along said first axis of said object.

12. The device of claim 7 in which said source further comprises at least one driver in operable communication with said source.

13. The device of claim 7 in which said processor further comprises:

at least one amplifier in operable communication with said sensor for amplifying said reflections;

at least one digitizer in operable communication with said amplifier;

at least one central processing unit (CPU) in operable communication with said digitizer;

at least one Read Only Memory (ROM) in operable communication with said CPU;

at least one Random Access Memory (RAM) in operable communication with said CPU;

at least one display in operable communication with said CPU;

at least one keypad in operable communication with said CPU;

at least one Analog and Digital Input/Output (A&

D I/O) device in operable communication with said CPU; and

at least one power supply in operable communication with said CPU.

14. The device of claim 13 further comprising at least one battery in operable communication with said power supply.

15. The device of claim 14 further comprising at least one battery charger suitable to be placed in operable communication with at least one said battery.

16. An acoustic sensor package having a proximal and a distal end, said sensor package facilitating obtaining a measure of bulk stress along a first axis of an object, comprising:

at least one each first and second elements and at least one each first and second connectors, said first and second connectors positioned on said proximal end, said first connector in operable communication with said first element and said second connector in operable communication with said second element,

wherein said first element facilitates communicating at least one acoustic signal in the form of a shear wave, and

wherein said second element facilitates communicating at least one acoustic signal in the form of a longitudinal wave; and

a housing, having a proximal and distal end, incorporating said elements and said connectors,

wherein said connectors are provided through an external surface of said proximal end of said housing, and

wherein said distal end of said housing is configured to transmit said acoustic signals, and

wherein said distal end of said housing or said portion of said object contacting said sensor is at least partially coated with shear gel.

17. The sensor of claim 16 in which said housing is a cylinder having said elements epoxied to a wear plate to facilitate the conduction of acoustic waves and particularly said shear wave between said elements and said wear plate that contacts said object via said shear gel.

18. The sensor of claim 16 in which said first element is a solid cylinder concentric with a longitudinal axis of said sensor and said second element is a hollow cylinder of wall thickness, t, arranged concentrically about said first element,

wherein t is approximately equal to the radius, r, of said first element.

19. A device for measuring bulk stress along a first axis of an object, comprising:

first means for detecting acoustic energy, said first means having a proximal and a distal end, said first means having at least one each first and second elements and at least one each first and second connectors, said first and second connectors positioned on said proximal end, said first connector in operable communication with said first element and said second connector in operable communication with said second element,

wherein said first element facilitates communicating at least one acoustic signal in the form of a shear wave, and

wherein said second element facilitates communicating at least one acoustic signal in the form of a longitudinal wave;

shear gel;

wherein said shear gel is coated on at least part of said distal end of said first means or on a portion of said object in contact with said device;

at least one means for generating acoustic signals,

wherein said means for generating acoustic signals produces at least first and second acoustic signals;

at least one means for processing said acoustic signals and reflections thereof from said distal end of said object along said first axis; and

at least one algorithm, said algorithm employing one value each of the velocities, V_s and V_l, of said signals from said first and second elements, respectively,

wherein processing said algorithm provides said measure of bulk stress.

20. The device of claim 19 in which said acoustic signals are ultrasonic signals.