Claims
- 1. A probe for performing non-destructive evaluation of conductive materials, said probe comprising:
at least one magnetic field generator means, comprising an electromagnet having a U-shaped core made of magnetizeable material with conductive wire coiled around a portion of said U-shaped core for applying a magnetic field to said material; at least one giant magnetoresistive material based sensor, straddle by said U shaped electromagnet having a sensitive axis proximate to said generator means and responsive to fluctuating signals induced by said magnetic fields; and, means, in communication with said at least one giant magnetoresistive material based sensor for detecting fluctuating changes in the resistance of the giant magnetoresistive material based sensor wherein said sensitive axis is substantially normal 10 to the surface of said conductive material.
- 2. An probe according to claim 1, wherein said means for detecting changes in resistance in said giant magnetoresistive sensor is selected from the group comprising means for measuring voltage, current, frequency and analyzing the same is electrically connected to said probe.
- 3. An probe according to claim 2, wherein said analysis means consist of a digital controller/analysis unit complete with frequency and time domain statistical algorithms connected to said probe.
- 4. A probe according to claim 1, wherein said giant magnetoresistive material based sensor is disposed substantially at the first terminal end of said probe.
- 5. The probe of claim 1, wherein said fluctuating signals are Barkhausen noise signals.
- 6. An probe according to claim 1, wherein said means for detecting changes in resistance of the GIANT MAGNETORESISTIVE material base sensor comprises means for conditioning the Barkhausen noise signals outputs from the sensor.
- 7. The probe according to claim 6 wherein said means for conditioning the Barkhausen noise signals comprises:
an instrumentation amplifier for each signal channel with said instrumentation amplifier being electrically connected to additional amplifying means, bandpass filtering means communicating with said instrumentation amplifier and additional amplifying means for eliminating unwanted noise signals from said Barkhausen noise signals; and, analog-to-digital means for converting the filtered output signals from said bandpass filtering means for storage in a digital storage media.
- 8. The apparatus of claim 3, wherein the digital controller/analysis unit is a digital computer system.
- 9. The probe of claim 1, wherein said GIANT MAGNETORESISTIVE material based sensor comprises four magnetoresistive material based elements arranged in a Wheatstone bridge configuration.
- 10. The probe of claim 9, wherein at least two of said four magnetoresistive material based elements are used to detect the Barkhausen induced noise in the material under non-destructive evaluation.
- 11. The probe of claim 8, wherein at least one of the four magnetoresistive material based elements is used to detect the strength of the magnetic field applied to the material under investigation.
- 12. An apparatus for measuring Barkhausen signals, comprising:
an electromagnet for inducing a magnetic field into a ferromagnetic material; a solid state Wheatstone Bridge circuit whose four elements consist of giant magnetoresistive material based elements configured to maximize the sensitivity of said Wheatstone Bridge circuit to Barkhausen noise signals created within a material; and, signal conditioning means comprising: an instrumentation amplifier; a high gain bandwidth amplifier; a bandpass filter for each detected signal; and signal analysis means all housed in an integral housing.
- 13. The apparatus of claim 12, wherein said signal analysis means is a true RMS voltmeter.
- 14. An apparatus for generating and detecting Barkhausen noise signals, said probe comprising:
at least one magnetic field generator means which consist of an electromagnet cooperating with a bipolar power supply driven between its various polarities via a waveform generator; at least one giant magnetoresistive material based sensor surrounded by one cylindrical sleeve, the pair having collinear axes proximate to said magnetic field generator means and responsive to Barkhausen noise signals induced by the magnetic field generating means, electrically connected to signal conditioning and analysis means; and, integral housing substantially encapsulating said at least one giant magnetoresistive material based sensor surrounded by one cylindrical sleeve, the pair having collinear axes proximate to said magnetic field generator means with the same being held fixed with potting means.
- 15. The apparatus of claim 14, wherein the said at least giant magnetoresistive sensor is potted with its sensitive axis collinear with the central axis of said at least one cylindrical sleeve.
- 16. The apparatus of claim 14, wherein the said at least one giant magnetoresistive sensor is potted with its sensitive axis orthogonal to the central vertical axis of said at least one cylindrical sleeve.
- 17. The apparatus of claim 14, wherein the said at least one cylindrical sleeve. Consist of dielectric material.
- 18. The apparatus of claim 14, wherein the said at least one cylindrical sleeve. Consist of mu-metal or another magnetic shielding material.
- 19. A probe having a graspable integral housing for performing non-destructive evaluation of material, said probe comprising:
a magnetic field generator means, comprising an U-shaped electromagnet a giant magnetoresistive material based sensor, straddle by said U shaped electromagnet having a sensitive axis proximate to said generator means and responsive to fluctuating magnetic signals induced by said magnetic fields; and, a magnetic field sensor disposed proximate the first end of said integral housing for measuring the magnetic field applied to a material.
CROSS REFERENCE OF RELATED APPLICATIONS
[0001] Pursuant to 35 U.S.C. Section 119, the benefit of priority from Provisional Application Number 60/227,265 with filing date Aug. 24, 2000 is claimed for this Non-Provisional Application.
Provisional Applications (1)
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Number |
Date |
Country |
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60227265 |
Aug 2000 |
US |