Method for detecting defects in conductive materials based on differences in magnetic field characteristics measured along the conductive materials

• US 10,088,452 B2
• Filed: 01/21/2016
• Issued: 10/02/2018
• Est. Priority Date: 01/12/2016
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Villani, Jr., Joseph A., Stetson, Jr., John B.
• Primary Examiner(s): NGUYEN, VINH P
• Application Number:
  US15/003,145
• Publication Number:
  US 20170199156A1
• Time in Patent Office: 985 Days
• CPC Class Codes: G01N 27/82 for investigating the presence of flaws

Abstract

A method includes passing a magnetometer along a length of a material. The method also includes measuring, via the magnetometer, a first magnetic field magnitude along a first portion of the length of the material and measuring, via the magnetometer, a second magnetic field magnitude along a second portion of the length of material. The method further includes determining that the material includes a defect along the second portion of the length of material by determining that the first magnetic field magnitude is different than the second magnetic field magnitude.

Claims

1. A method comprising:

passing a magnetometer along a length of a material;

measuring, via the magnetometer, a first magnetic field magnitude along a first portion of the length of the material;

measuring, via the magnetometer, a second magnetic field magnitude along a second portion of the length of material; and

determining that the material comprises a defect along the second portion of the length of material by determining that the first magnetic field magnitude is different than the second magnetic field magnitude.

2. The method of claim 1, wherein said determining that the first magnetic field magnitude is different than the second magnetic field magnitude comprises determining that the first magnetic field magnitude is different than the second magnetic field magnitude by at least a first threshold.

3. The method of claim 1, wherein the first magnetic field magnitude and the second magnetic field magnitude are measured at a 10,000 Hertz (Hz) bandwidth.

4. The method of claim 1, wherein the first magnetic field magnitude and the second magnetic field magnitude are measured at a 50,000 Hertz (Hz) bandwidth.

5. The method of claim 1, wherein the first magnetic field magnitude and the second magnetic field magnitude are measured at a sensitivity of 10⁻

9 Tesla.

6. The method of claim 1, wherein said measuring the first magnetic field magnitude comprises measuring the first magnetic field magnitude in three directions.

7. The method of claim 6, wherein each of the three directions are orthogonal to one another.

8. The method of claim 1, wherein said passing the magnetometer along the length of the material comprises maintaining a consistent distance between the magnetometer and the length of the material.

9. The method of claim 8, wherein the consistent distance is a distance between five and ten meters.

10. The method of claim 1, wherein the material is a ferrous material.

11. The method of claim 1, wherein the material is ferromagnetic.

12. The method of claim 1, wherein the material comprises at least one of a railway rail or a pipe.

13. The method of claim 1, wherein the material comprises a component of machinery.

14. The method of claim 1, wherein the defect comprises a break, a crack, a hole, a pit, or a gouge in the length of the material.

15. The method of claim 1, further comprising passing a second magnetometer along the length of the material,

wherein the magnetometer and the second magnetometer are configured to measure a magnetic field at different locations simultaneously.