Means and method for ultrasonic measurement of material properties

• US 5,154,081 A
• Filed: 01/28/1991
• Issued: 10/13/1992
• Est. Priority Date: 07/21/1989
• Status: Expired due to Fees

• Current Assignee: Iowa State University Research Foundation Incorporated (Iowa State University)
• Original Assignee: Iowa State University Research Foundation Incorporated (Iowa State University)
• Inventors: Alers, George A., Thompson, Robert B., Wormley, Samuel J.
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US07/647,484
• Time in Patent Office: 624 Days
• Field of Search: 73/643, 73/597, 73/641
• US Class Current: 73/597
• CPC Class Codes: G01N 2291/0234 Metals, e.g. steel
• CPC Class Codes: G01N 2291/0289 Internal structure, e.g. defects, grain size, texture
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 2291/0427 Flexural waves, plate waves, e.g. Lamb waves, tuning fork, cantilever
• CPC Class Codes: G01N 29/07 by measuring propagation velocity or propagation time of acoustic waves

Abstract

The system for field measurement of texture, stress and related material properties such as formability parameters using ultrasonic velocity measurements through crystalline plate or sheet. Electromagnetic acoustic transducers are utilized to generate, transmit, and receive ultrasonic bursts through the plate at different angular orientations with respect to the plane of the plate. Two of the transducers are driven in series when generating the ultrasonic bursts. Time measurements between transmission and reception of the bursts are precisely derived and converted into velocities. Information regarding stress, texture, and other related material properties such as formability parameters can be derived from these velocity measurements. The system is adjustable to be used for both ferrous and nonferrous crystalline plate. Alteration of the types of ultrasonic waves utilized, and the methods of generating the waves allows different properties such as texture and stress to be derived.

Claims

1. A method for field ultrasonic measurement of texture, stress, and related material properties including but not limited to formability parameters comprising:

positioning an array of electromagnetic acoustic transducers along an axis;

fixing first and second of said transducers of the array at a precisely known distance from one another along the axis;

fixing a third said transducer of the array a distance along the axis from the first and the second transducers but not between the first and second transducers; and

driving the first and second transducers in series to produce separate ultrasonic waves which are received by the third transducer, the first and second transducers being driven in series to prevent any differences in phase between the ultrasonic waves launched by the first and second transducers caused by differential lift off of one or both of the first and second transducers.

2. The method of claim 1 wherein at least one transducer is a Lamb wave producing transducer.

3. The method of claim 1 wherein at least one transducer includes a magnet, the magnet being a pulsed electromagnet.

4. The method of claim 1 wherein a metal plate having a rolling direction is measured by orienting the array of transducers in relationship to the rolling direction of metal plate.

5. The method of claim 4 wherein the array of transducers is angularly adjustable between at least 0°

, 45° and

90°

with respect to the rolling direction of the plate.

6. The method of claim 1 wherein at least one transducer is a horizontally polarized shear wave producing transducer.

7. The method of claim 1 wherein at least one transducer includes a magnet, the magnet being a permanent magnet.

8. A method of performing ultrasonic measurements to analyze one or more of texture, stress, and related material properties including but not limited to formability parameters, in ferrous and non-ferrous material comprising:

generating ultrasonic energy in the form of ultrasonic waves in the material by utilizing a first pair of electromagnetic acoustic transducers connected in series to generate said ultrasonic energy in two bursts which propagate through the material;

receiving said bursts at a third ultrasonic electromagnetic acoustic transducer and measuring the received bursts as a function of time;

Fourier transforming the measured, received bursts as a function of time to convert information contained in the received bursts to a frequency domain;

inferring velocities of ultrasound from variation of phase of Fourier transforms of the received bursts with frequency; and

deriving one or more of texture, stress, formability or related parameters by correlation with the velocities.

9. The method of claim 8 wherein the ultrasonic waves are Lamb waves generated in ferrous materials with said electromagnetic acoustic transducers each including at least one pulsed electromagnet.

10. The method of claim 8 wherein the ultrasonic waves are horizontally polarized shear waves generated in ferrous materials with said electromagnetic acoustic transducers including at least one pulsed electromagnet.

11. The method of claim 8 wherein the ultrasonic waves are Lamb waves generated in non-ferrous materials with said electromagnetic acoustic transducers including at least one permanent magnet.

12. The method of claim 8 wherein the ultrasonic waves are horizontally polarized shear waves generated in non-ferrous materials with said electromagnetic acoustic transducers including at least one permanent magnet.

13. A field instrument for ultrasonic measurement of texture, stress and related material properties including but not limited to formability comprising:

a portable housing including control means, transducer array head connection means, first and second operation circuit means, processing means, and power supply connection means for connecting electrical power to the field instrument;

one or more transducer array heads connectable to the transducer array head connection means;

an array of electromagnetic acoustic transducers positioned in each transducer array head, each array including electromagnetic acoustic transducers having a means to establish a magnetic bias field;

the first operation circuit means for firing at least two transducers of each array including firing first and second transducers of an array in series to create first and second ultrasonic bursts;

the second operation circuit means for measuring reception of the bursts of ultrasonic energy at a third transducer of the array as a function of time;

the processing means for processing information received at the third transducer and including means for Fourier transforming the measurements as a function of time to convert the information from a time domain to a frequency domain for inferring velocities of ultrasound from variation of phase of Fourier transforms of the information with frequency, and for deriving one or more of texture, stress, formability or related parameters by correlation with the velocities;

the array head connection means allowing connection of a desired array of transducers for a measurement purpose; and

the control means allowing control of the operation circuit means and processing means.

14. The field instrument of claim 13 wherein at least one electromagnetic acoustic transducer of the array includes a pulsed electromagnet.

15. The field instrument of claim 13 wherein at least one of the electromagnetic acoustic transducers of the array includes a permanent magnet.

16. A field instrument for ultrasonic nondestructive measurement of at least one of texture, stress, or related material properties including but not limited to formability, comprising:

a portable housing including;

(a) user control means for operating the instrument;

(b) processing means for data acquisition, processing of data, providing instructions for driving signals according to input from the user control means; and

(c) probe control means to provide the driving signals to a probe means for transmitting and receiving ultrasound according to instructions from the processing means;

the probe means being moveably positionable relative to the housing for placement at or near a material being measured;

a connection means operatively connecting the probe means to the housing; and

one or more arrays of electromagnetic acoustic transducers positioned in the probe means, each array consisting of at least one set of two transmitting electromagnetic acoustic transducers connected in series electrically, and at least one receiving electromagnetic transducer.

17. The instrument of claim 16 wherein at least one array includes pulsed electromagnetic acoustic transducers for generating Lamb waves to measure texture in a ferrous material.

18. The instrument of claim 16 wherein at least one array includes pulsed electromagnetic acoustic transducers for generating horizontally polarized shear weaves to measure stress in a ferrous material.

19. The instrument of claim 16 wherein at least one array includes permanent magnet electromagnetic acoustic transducers for generating Lamb waves to measure texture in a non-ferrous material.

20. The instrument of claim 16 wherein at least one array includes permanent magnet electromagnetic acoustic transducers for generating horizontally polarized shear waves to measure stress in a non-ferrous material.

21. The instrument of claim 16 further comprising two or more probe means, an array of electromagnetic acoustic transducers in each probe means being selected from the set consisting of pulsed and permanent magnet electromagnetic acoustic transducers.

22. The instrument of claim 21 wherein the electromagnetic acoustic transducers include a pulsed electromagnet to measure stress in ferrous materials.

23. The instrument of claim 21 wherein the electromagnetic acoustic transducers include a permanent magnet for measuring stress in non-ferrous materials.

24. The instrument of claim 21 wherein the electromagnetic acoustic transducers includes a pulsed electromagnet to measure texture in ferrous materials.

25. The instrument of claim 21 wherein the electromagnetic acoustic transducers includes permanent magnet for measuring texture in non-ferrous materials.