US4048847A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nondestructive detection of stress
Assignee: Boeing North American Inc
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Filing: 1976-07-14
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Granted: 1977-09-20
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Expires: 1996-07-14
Abstract
Abstract Stress is detected by magnetostrictively generating vibrations which are detected at a location spaced from the region of generation. The efficiency of the generation is indicative of stress if the region is magnetically biased to less than maximum amplitude for the vibrations as produced. Preferably, the needed bias for generating vibrations at a constant level is used as stress indicator. Due to reciprocity of magnetostriction, the efficiency of generating magnetic oscillations by means of elastic vibrations in a biased region can be detected.
Inventors
- 👤 George A. Alers
- 👤 Robert B. Thompson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:50
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/12; G01R33/18; G01N; G01N29/00; G01N29/22; G01N29/24; G01N29/2412; G01N2291/00; G01N2291/04; G01N2291/042; G01N2291/0423; G01N2291/0426; G01N2291/0427
Claims Analysis
Total Claims: 41
Claim 1
Independent Claim
126 words
A method of measuring stress in a part of a structural material comprising the steps of: generating magnetically in the material vibrations as a result of alternation of magnetostriction in the material and in a well defined first location of the structural part; detecting at a different location the vibrations as generated and launched from the first location, thereby producing a signal having a particular amplitude; deriving from the preceding steps a representation of the efficiency of the generation of the vibrations at said first location; and comparing the representation with a representation of a generation of vibrations generated and detected in a similar manner but at a different location of the same part or at a location of a different part of the same material.
Claim 2
Independent Claim
126 words
A method of measuring stress in a part of a structural material comprising the steps of: generating magnetically in the material vibrations as a result of alternation of magnetostriction in the material and in a well defined first location of the structural part; detecting at a different location the vibrations as generated and launched from the first location, thereby producing a signal having a particular amplitude; deriving from the preceding steps a representation of the efficiency of the generation of the vibrations at said first location; and comparing the representation with a representation of a generation of vibrations generated and detected in a similar manner but at a different location of the same part or at a location of a different part of the same material.
Claim 3
Dependent Claim
48 words
A method as in claim 1 wherein the generating step is a composite step of a. magnetically biasing the said location; and b. superimposing an oscillatory component upon the bias; the efficiency being given by the relation of the magnetic bias and the amplitude of the detected vibrations.
Claim 4
Dependent Claim
19 words
A method as in claim 2 wherein the said representation is the bias needed to obtain said particular amplitude.
Claim 5
Dependent Claim
16 words
A method as in claim 2 wherein the representation is the amplitude for a given bias.
Claim 6
Dependent Claim
28 words
A method as in claim 2, wherein the said representation is an amplitude of the oscillatory component for a given bias and a particular amplitude of detected vibrations.
Claim 7
Independent Claim
73 words
A method of measuring stress in a part of a structural material, comprising the steps of: generating vibrations in the part which step includes a. magnetically biasing a region of said part; and b. superimposing oscillatory magnetic field upon the bias; detecting vibrations as transmitted from said region; and providing a signal representing the detected amplitude, the signal in correlation with the biasing representing the stress condition in the region of said part.
Claim 8
Independent Claim
73 words
A method of measuring stress in a part of a structural material, comprising the steps of: generating vibrations in the part which step includes a. magnetically biasing a region of said part; and b. superimposing oscillatory magnetic field upon the bias; detecting vibrations as transmitted from said region; and providing a signal representing the detected amplitude, the signal in correlation with the biasing representing the stress condition in the region of said part.
Claim 9
Dependent Claim
28 words
The method as in claim 6, wherein the biasing step includes biasing the region by a magnetic field weaker than needed for generating vibrations magnetostrictically of maximum amplitude.
Claim 10
Dependent Claim
47 words
Method of detecting microstructure conditions in a part of a structural material such as stress, plastic deformation, dislocations, etc., comprising the steps of generating in a region of said part magnetostrictive oscillations, and detecting efficiency of the generation in representation of the microstructure conditions in said region.
Claim 11
Dependent Claim
47 words
Method of detecting microstructure conditions in a part of a structural material such as stress, plastic deformation, dislocations, etc., comprising the steps of generating in a region of said part magnetostrictive oscillations, and detecting efficiency of the generation in representation of the microstructure conditions in said region.
Claim 12
Dependent Claim
19 words
The method as in claim 8, wherein the detecting step includes the detection of surface waves in the part.
Claim 13
Dependent Claim
19 words
The method as in claim 8, wherein the detecting step includes the detection of bulk waves in the part.
Claim 14
Dependent Claim
19 words
The method as in claim 8, wherein the detecting step includes the detection of Lamb waves in the part.
Claim 15
Dependent Claim
20 words
The method as in claim 8, wherein the generating step includes the electromagnetic generation of magnetostrictive vibrations in the part.
Claim 16
Dependent Claim
25 words
The method as in claim 8, wherein the generating step includes the magnetostrictive generation of a variable magnetic field on the basis of elastic vibrations.
Claim 17
Independent Claim
55 words
A method of detecting microstructure conditions in a structural material, such as stress, plastic deformation, dislocations, comprising: magnetically biasing a particular region of the material; causing magnetostrictive oscillations to be generated in the particular region of the material; and detecting the efficiency of the generation in representation of the microstructure conditions of the said region.
Claim 18
Independent Claim
55 words
A method of detecting microstructure conditions in a structural material, such as stress, plastic deformation, dislocations, comprising: magnetically biasing a particular region of the material; causing magnetostrictive oscillations to be generated in the particular region of the material; and detecting the efficiency of the generation in representation of the microstructure conditions of the said region.
Claim 19
Dependent Claim
40 words
Method as in claim 14, said oscillations being elastic vibrations generated by applying oscillations of a magnetic field to said region and superimposing them upon said bias, the detecting step including detecting an amplitude of the elastic vibrations as generated.
Claim 20
Dependent Claim
30 words
Method as in claim 14, said oscillations being oscillations of magnetizations resulting from elastic vibrations in said region, the detecting step including detecting an amplitude of the oscillations of magnetization.
Claim 21
Dependent Claim
47 words
Method as in claim 14, wherein first signals are used for generating said oscillations and second signals are produced pursuant to the detecting, the detection of the efficiency including maintaining said magnetically biasing constant and said first signals constant and detecting the amplitude of the third one.
Claim 22
Independent Claim
98 words
A method of measuring stress in a part of a structural material, comprising the steps of: magnetically biasing a first region of said part; magnetically exciting the first region to obtain magnetostrictive oscillations; detecting mechanical vibrations as emitted by said first region; repeating the aforementioned steps for a different region of the same part of a different part; determining the magnetic bias and the detected vibrations as per said aforementioned steps as well as repeated; and deriving a representation of the relative stress in the first and second regions from said determined biases and from said detected vibrations.
Claim 23
Independent Claim
98 words
A method of measuring stress in a part of a structural material, comprising the steps of: magnetically biasing a first region of said part; magnetically exciting the first region to obtain magnetostrictive oscillations; detecting mechanical vibrations as emitted by said first region; repeating the aforementioned steps for a different region of the same part of a different part; determining the magnetic bias and the detected vibrations as per said aforementioned steps as well as repeated; and deriving a representation of the relative stress in the first and second regions from said determined biases and from said detected vibrations.
Claim 24
Dependent Claim
32 words
A method as in claim 18, and including the steps of adjusting the biasing to obtain constant amplitudes, the adjusted bias for the first and second regions representing the relative stress therein.
Claim 25
Dependent Claim
17 words
A method as in claim 18, and including the steps of determining said amplitudes for constant bias.
Claim 26
Independent Claim
135 words
A method of measuring stress in a part of a structural material, comprising the steps of: generating a magnetic field in a limited region in said part; causing said field to vary at a particular high frequency so that vibrations are generated in the region on account of magnetostriction; detecting the vibrations at a location spaced-apart from said region, said vibrations as detected having a maximum value for a first particular value of the magnetic field, the magnetic field as generated pursuant to the generating step being smaller than the first particular value; deriving from the preceding steps an indication of the efficiency of the generation; repeating the previous steps for a different location; and comparing the resulting indications with each other to obtain a repesentation of the relative stress conditions in said locations. representation
Claim 27
Independent Claim
135 words
A method of measuring stress in a part of a structural material, comprising the steps of: generating a magnetic field in a limited region in said part; causing said field to vary at a particular high frequency so that vibrations are generated in the region on account of magnetostriction; detecting the vibrations at a location spaced-apart from said region, said vibrations as detected having a maximum value for a first particular value of the magnetic field, the magnetic field as generated pursuant to the generating step being smaller than the first particular value; deriving from the preceding steps an indication of the efficiency of the generation; repeating the previous steps for a different location; and comparing the resulting indications with each other to obtain a repesentation of the relative stress conditions in said locations. representation
Claim 28
Dependent Claim
24 words
The method as in claim 21, wherein the generating step includes: a. providing of a magnetic bias; and b. superimposing a variable magnetic field.
Claim 29
Dependent Claim
27 words
The method as in claim 22, wherein said bias is adjustable and the representations are adjusted values for said bias, to obtain detected vibrations of constant amplitude.
Claim 30
Dependent Claim
37 words
The method as in claim 22, wherein the indications are amplitude values of the variable magnetic field at each of said different locations, and including the step of holding the bias and detected vibrations to constant values.
Claim 31
Dependent Claim
25 words
The method as in claim 21, including the step of holding the bias constant, the representations being amplitude values as detected for the constant bias.
Claim 32
Independent Claim
115 words
A method of measuring stress in a structural material, comprising the steps of: i. generating a first signal being a magnetic biasing field to be effective in limited region of the material; ii. superimposing a second signal being an oscillatory component, upon said biasing field so that vibrations are generated in the region on account of magnetostriction; iii. detecting said vibrations at locations spaced from said region and generating a third signal representative thereof; maintaining two of said first, second and third signals constant; and deriving an indication of the efficiency of the generation of said vibrations from the resulting value of the remaining signal, said indication being representative of the stress in said region.
Claim 33
Independent Claim
115 words
A method of measuring stress in a structural material, comprising the steps of: i. generating a first signal being a magnetic biasing field to be effective in limited region of the material; ii. superimposing a second signal being an oscillatory component, upon said biasing field so that vibrations are generated in the region on account of magnetostriction; iii. detecting said vibrations at locations spaced from said region and generating a third signal representative thereof; maintaining two of said first, second and third signals constant; and deriving an indication of the efficiency of the generation of said vibrations from the resulting value of the remaining signal, said indication being representative of the stress in said region.
Claim 34
Independent Claim
75 words
A method of detecting stress in structural material comprising: magnetically biasing a particular region; generating an oscillating magnetic field in said region; detecting elastic vibrations as produced in said region including detecting a maximum in the amplitude of the vibrations by varying said biasing; reducing said biasing so that the vibrations as detected have an amplitude which is a particular fraction of the said maximum; and determining a quantity representative of the bias as reduced.
Claim 35
Independent Claim
75 words
A method of detecting stress in structural material comprising: magnetically biasing a particular region; generating an oscillating magnetic field in said region; detecting elastic vibrations as produced in said region including detecting a maximum in the amplitude of the vibrations by varying said biasing; reducing said biasing so that the vibrations as detected have an amplitude which is a particular fraction of the said maximum; and determining a quantity representative of the bias as reduced.
Claim 36
Independent Claim
152 words
A method of measuring stress in a part of a structural material comprising the steps of: generating magnetically in the material vibrations as a result of alternation of magnetostriction in the material and in a well defined first location of the structural part by (a) magnetically biasing said location, and (b) superimposing an oscillatory component upon the bias; detecting at a different location the vibrations as generated and launched from the first location, thereby producing a signal having a particular amplitude; deriving from the preceding steps a representation of the efficiency of the generation of the vibrations at said first location by determining the magnetic bias needed to obtain said particular amplitude; and comparing the representation with a representation of a generation of vibrations generated and detected in a similar manner but at a different location of the same part or at a location of a different part of the same material.
Claim 37
Independent Claim
152 words
A method of measuring stress in a part of a structural material comprising the steps of: generating magnetically in the material vibrations as a result of alternation of magnetostriction in the material and in a well defined first location of the structural part by (a) magnetically biasing said location, and (b) superimposing an oscillatory component upon the bias; detecting at a different location the vibrations as generated and launched from the first location, thereby producing a signal having a particular amplitude; deriving from the preceding steps a representation of the efficiency of the generation of the vibrations at said first location by determining the magnetic bias needed to obtain said particular amplitude; and comparing the representation with a representation of a generation of vibrations generated and detected in a similar manner but at a different location of the same part or at a location of a different part of the same material.
Claim 38
Independent Claim
108 words
A method of measuring stress in a part of a structural material, comprising steps of: magnetically biasing a first region of said part; magnetically exciting the first region to obtain magnetostrictive oscillations; detecting mechanical vibrations as emitted by said first region; adjusting the biasing to obtain constant amplitudes of said vibrations; repeating the aforementioned steps for a different region of the same part or a different part; determining the magnetic bias and the detected vibrations as per said aforementioned steps as well as repeated; and deriving a representation of the relative stress in the first and second regions from said adjusted biases for the first and second regions.
Claim 39
Independent Claim
108 words
A method of measuring stress in a part of a structural material, comprising steps of: magnetically biasing a first region of said part; magnetically exciting the first region to obtain magnetostrictive oscillations; detecting mechanical vibrations as emitted by said first region; adjusting the biasing to obtain constant amplitudes of said vibrations; repeating the aforementioned steps for a different region of the same part or a different part; determining the magnetic bias and the detected vibrations as per said aforementioned steps as well as repeated; and deriving a representation of the relative stress in the first and second regions from said adjusted biases for the first and second regions.
Claim 40
Independent Claim
157 words
A method of measuring stress in a part of a structural material, comprising the steps of: generating a magnetic field in a limited region in said part by providing an adjustable magnetic bias and superimposing a variable magnetic field; causing said field to vary at a particular high frequency so that vibrations are generated in the region on account of magnetostriction; detecting the vibrations at a location spaced-apart from said region, said vibrations as detected having a maximum value for a first particular value of the magnetic field, the magnetic field as generated pursuant to the generating step being smaller than the first particular value; deriving from the preceding steps an indication of the efficiency of the generation by adjusting said bias to obtain detected vibrations of constant amplitude; repeating the previous steps for a different location; and comparing the resulting indications with each other to obtain a representation of the relative stress conditions in said locations.
Claim 41
Independent Claim
157 words
A method of measuring stress in a part of a structural material, comprising the steps of: generating a magnetic field in a limited region in said part by providing an adjustable magnetic bias and superimposing a variable magnetic field; causing said field to vary at a particular high frequency so that vibrations are generated in the region on account of magnetostriction; detecting the vibrations at a location spaced-apart from said region, said vibrations as detected having a maximum value for a first particular value of the magnetic field, the magnetic field as generated pursuant to the generating step being smaller than the first particular value; deriving from the preceding steps an indication of the efficiency of the generation by adjusting said bias to obtain detected vibrations of constant amplitude; repeating the previous steps for a different location; and comparing the resulting indications with each other to obtain a representation of the relative stress conditions in said locations.
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) | 1980-09-19 | 1981-03-21 | 1981-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-19 | 1985-03-21 | 1985-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-19 | 1989-03-21 | 1989-09-20 | $7700.00 | Window Closed / Lapsed |