Patent US3792348A successfully refreshed from Google Patents.
US3792348A
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Method of determining stress in a ferromagnetic member using magnetoabsorption
Assignee: Individual
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Filing: 1971-11-19
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Granted: 1974-02-12
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Expires: 1991-11-19
Abstract
Abstract Magnetoabsorption apparatus for indicating changes in stress in ferrous materials and nonferrous materials including a ferrous film joined thereto, an inductively coupled radio frequency field coupled to the ferrous material, a means for applying the field in a manner to use the reversible relative permeability as a function of the stress in the member, the stress being indicated by use of a magnetoabsorption detector calibrated in stress units, and indicative of the direction, ampliutde, and type of stress.
Inventors
- 👤 J Arambula
- 👤 J Claassen
- 👤 W Rollwitz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:01
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01L; G01L1/00; G01L1/12; G01L1/125; G01L1/127
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
275 words
A method of determining the stress in a ferromagnetic member comprising the steps of: placing the member in a field of radiofrequency coil in a manner to make the impedance of the coil at least partially dependent on the member; placing a low frequency bias field in the member to provide sufficient energy to the field that the relative reversable permeability of the member is at least partially dependent on the stress in the member; altering the direction of the bias field between positions which are parallel to and perpendicular to the direction of the stress in the member; changing the stress in the member incrementally from a first value to a second value; observing the relative changes in impedance of the radio frequency coil as the bias field is positioned parallel and perpendicular to the direction of stress; determining from the relative changes in impedance whether the stress is tension or compression; changing the stress in the member from a first to a second value in which the relative direction of change is known and the actual values of stress are indeterminate, and thereafter observing the relative changes in the impedance of the radio frequency coil, and the determining from the relative changes in impedance the magnitude of the stress; and, graphically representing the impedance changes in a quadrant wherein the axes are the relative stress and the change in impedance to form a first curve thereon of data obtained with the bias field parallel to the stress, and a second curve thereon of data obtained with the bias field perpendicular to the stress, determining a graphic point of intersection of the two curves.
Claim 2
Independent Claim
275 words
A method of determining the stress in a ferromagnetic member comprising the steps of: placing the member in a field of radiofrequency coil in a manner to make the impedance of the coil at least partially dependent on the member; placing a low frequency bias field in the member to provide sufficient energy to the field that the relative reversable permeability of the member is at least partially dependent on the stress in the member; altering the direction of the bias field between positions which are parallel to and perpendicular to the direction of the stress in the member; changing the stress in the member incrementally from a first value to a second value; observing the relative changes in impedance of the radio frequency coil as the bias field is positioned parallel and perpendicular to the direction of stress; determining from the relative changes in impedance whether the stress is tension or compression; changing the stress in the member from a first to a second value in which the relative direction of change is known and the actual values of stress are indeterminate, and thereafter observing the relative changes in the impedance of the radio frequency coil, and the determining from the relative changes in impedance the magnitude of the stress; and, graphically representing the impedance changes in a quadrant wherein the axes are the relative stress and the change in impedance to form a first curve thereon of data obtained with the bias field parallel to the stress, and a second curve thereon of data obtained with the bias field perpendicular to the stress, determining a graphic point of intersection of the two curves.
Claim 3
Dependent Claim
58 words
The method of claim 1 including the step of placing a zero stress line on the graphic representation including the two curves, and determining the stress originally in the member dependent on the angle of the zero stress line, and a line drawn from the origin of the graph to the point of intersection of the two curves.
Claim 4
Dependent Claim
39 words
The method step of claim 2 wherein the stress is given by the relationship: Stress K(arc tan Za/Zb -45*) Where: K A constant in PSI/degree. Za Impedance with the bias field parallel. Zb Impedance with the bias field perpendicular.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-11 | 1977-08-13 | 1978-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-11 | 1981-08-13 | 1982-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-11 | 1985-08-13 | 1986-02-12 | $7700.00 | Window Closed / Lapsed |