Patent US3825819A successfully refreshed from Google Patents.
US3825819A
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Dynamic proof loading of metal bond structures using pulsed magnetic fields
Assignee: Boeing Co
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Filing: 1973-03-12
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Granted: 1974-07-23
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Expires: 1993-03-12
Abstract
Abstract A method and apparatus for developing tensile stress within bonded metal structures. A magnetic field is first developed slowly in the bonded metal structure by pulsing a coil adjacent the metal structure with a high energy electric pulse. At substantially the peak of the slow high energy pulse, a comparatively fast pulse in an opposing current direction is applied through the coil adjacent the same surface. The fast negative pulse effectively shuts off the slow pulse, resulting in a very rapid decrease in the magnetic field adjacent the surface of the metal structure. The magnetic field internal the structure initially established by the slow pulse is, during the fast negative pulse, at or near a maximum, and just beginning to diffuse through the structure. This creates a large negative magnetic field gradient across the structure from internal the structure to the surface nearest the coils, and thus, a resulting large tensile stress on the bond line.
Inventors
- 👤 K Hansen
- 👤 C Lunden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 09:23
CPC Classifications
G; G01; G01N; G01N3/00; G01N3/30; G01N3/317; G01N19/00; G01N19/04; G01N2203/00; G01N2203/0014; G01N2203/0016; G01N2203/0019
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
149 words
A method of testing adhesive bond lines in a laminated article having at least one surface, which article is receptive to the establishment of a magnetic field therein, comprising the steps of: establishing a first magnetic field within said article, including said adhesive bond line, which first magnetic field reaches a predetermined amplitude; rapidly decreasing said first magnetic field in the vicinity of the one surface of said laminated article at such a rate that a substantial negative field gradient is established between the one surface and said adhesive bond line before said first magnetic field in the vicinity of said bond line can substantially collapse from said predetermined amplitude if otherwise permitted to collapse upon the initiation of the step of decreasing, said negative field gradient resulting in a stress on said adhesive bond line; and detecting a bond failure in said laminated article due to said stress.
Claim 2
Independent Claim
149 words
A method of testing adhesive bond lines in a laminated article having at least one surface, which article is receptive to the establishment of a magnetic field therein, comprising the steps of: establishing a first magnetic field within said article, including said adhesive bond line, which first magnetic field reaches a predetermined amplitude; rapidly decreasing said first magnetic field in the vicinity of the one surface of said laminated article at such a rate that a substantial negative field gradient is established between the one surface and said adhesive bond line before said first magnetic field in the vicinity of said bond line can substantially collapse from said predetermined amplitude if otherwise permitted to collapse upon the initiation of the step of decreasing, said negative field gradient resulting in a stress on said adhesive bond line; and detecting a bond failure in said laminated article due to said stress.
Claim 3
Dependent Claim
41 words
A method in accordance with claim 1, wherein the step of decreasing includes the step of generating a second magnetic field in the vicinity of the one surface of said laminated article, said second magnetic field opposing said first magnetic field.
Claim 4
Dependent Claim
36 words
A method in accordance with claim 2, wherein the step of generating includes applying a first current pulse of a given polarity through an inductive system positioned away from the one surface of said laminated article.
Claim 5
Dependent Claim
33 words
A method in accordancE with claim 3, wherein the step of establishing includes applying a second current pulse of a polarity opposite to that of said first current pulse through said inductive system.
Claim 6
Dependent Claim
27 words
A method in accordance with claim 4, wherein the rise time of said second pulse is slow compared to the rise time of said first current pulse.
Claim 7
Dependent Claim
26 words
A method in accordance with claim 5, wherein said first current pulse is initiated in time at substantially the peak value of said second current pulse.
Claim 8
Dependent Claim
33 words
A method in accordance with claim 6, wherein the magnetic field present in the vicinity of said one surface is substantially zero when said first current pulse is at substantially a peak value.
Claim 9
Dependent Claim
31 words
A method in accordance with claim 7, wherein the duration of said first current pulse from initiation to peak value is substantially in the range of 0.5 microseconds to 20.0 microseconds.
Claim 10
Dependent Claim
31 words
A method in accordance with claim 8, wherein the duration of said second current pulse from initiation to peak value is substantially with the range of 0.2 milliseconds to 10 milliseconds.
Claim 11
Dependent Claim
20 words
A method in accordance with claim 1, including the step of terminating the step of decreasing at a predetermined time.
Claim 12
Independent Claim
149 words
An apparatus for testing an adhesive bond line in a laminated article having at least one surface, which article is receptive to the establishment of a magnetic field therein, comprising: means for establishing a first magnetic field within said laminated article, including said adhesive bond line, which first magnetic field rises to a predetermined amplitude; means for rapidly decreasing said first magnetic field at the one surface of said laminated article at such a rate that a substantial negative magnetic field gradient is established between the one surface and said adhesive bond line before said first magnetic field can substantially collapse from said predetermined amplitude if otherwise permitted to collapse upon the initiation of the decreasing of said first magnetic field at the one surface, said negative field gradient resulting in a stress on said adhesive bond line; and means for detecting a delamination of said adhesive bond line.
Claim 13
Independent Claim
149 words
An apparatus for testing an adhesive bond line in a laminated article having at least one surface, which article is receptive to the establishment of a magnetic field therein, comprising: means for establishing a first magnetic field within said laminated article, including said adhesive bond line, which first magnetic field rises to a predetermined amplitude; means for rapidly decreasing said first magnetic field at the one surface of said laminated article at such a rate that a substantial negative magnetic field gradient is established between the one surface and said adhesive bond line before said first magnetic field can substantially collapse from said predetermined amplitude if otherwise permitted to collapse upon the initiation of the decreasing of said first magnetic field at the one surface, said negative field gradient resulting in a stress on said adhesive bond line; and means for detecting a delamination of said adhesive bond line.
Claim 14
Dependent Claim
34 words
An apparatus according to claim 11, wherein said decreasing means includes means for generating a second magnetic field in the vicinity of said one surface, said second magnetic field opposing said first magnetic field.
Claim 15
Dependent Claim
66 words
An apparatus according to claim 12, including a coil means positioned adjacent to but not touching said one surface, means for generating a first current pulse of a given polarity, and means for applying said first current pulse to said coil means, thereby generating said second magnetic field, the generation of said second magnetic field reducing the magnetic field at said one surface substantially to zero.
Claim 16
Dependent Claim
66 words
An apparatus according to claim 13, wherein said establishing means includes means for generating a second current pulse of a polarity opposite to that of said first current pulse, and means for connecting said second current pulse to said coil means, which second current pulse establishes an expanding first magnetic field outward from said coil means, establishing said first magnetic field encompassing said adhesive bond line.
Claim 17
Dependent Claim
37 words
An apparatus according to claim 14, including means for controlling the initiation of said first and second current pulses, said first current pulse being initiated in time at substantially a peak value of said second current pulse.
Claim 18
Dependent Claim
51 words
An apparatus according to claim 14, wherein said second current pulse generating means includes first energy storage means and first switching means, said first current pulse being of such a magnitude that said predetermined amplitude of said first magnetic field is substantially within the range of 30 kilogauss to 80 kilogauss.
Claim 19
Dependent Claim
20 words
An apparatus according to claim 12, including means for terminating the operation of said decreasing means at a predetermined time.
Claim 20
Dependent Claim
25 words
The apparatus accordIng to claim 17, wherein said terminating means includes a means for connecting said decreasing means to ground potential at said predetermined time.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-22 | 1978-01-21 | 1978-07-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-22 | 1982-01-21 | 1982-07-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-22 | 1986-01-21 | 1986-07-23 | $7700.00 | Window Closed / Lapsed |