US3786679A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fatigue indication
Assignee: Battelle Memorial Institute Inc
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Filing: 1972-04-12
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Granted: 1974-01-22
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Expires: 1992-04-12
Abstract
Abstract A device for indicating accumulated fatigue in a selected portion of a structural member. An elongate electrically conductive foil coupon has crack initiating slots of different sizes or shapes, or oriented at different angles, in regions that crack in response to fatigue and thus increase the electrical resistance between selected points. An adhesive securely bonds the coupon to the selected portion of the structural member, transmitting any strain therein to the coupon, which cracks at a lower level of accumulated fatigue than is enough to crack the structural member in the selected portion. Means responsive to the electrical resistance between the selected points on the coupon provide warning indications in time to avoid rupture of the structural member.
Inventors
- 👤 N Crites
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 22:14
CPC Classifications
G; G01; G01L; G01L1/00; G01L1/20; G01L1/22
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
101 words
A device for indicating accumulated fatigue in a selected portion of a structural member, comprising an elongate foil coupon having regions that crack in response to fatigue therein, and adhesive means securely bonding the coupon to the structural member in the selected portion to transmit to the coupon any strains therein to which the structural member is subjected; a plurality of crack initiating means being provided in the coupon, and the adhesive means providing a substantially continuous bond between the structural member and the regions that crack except in a narrow unbonded area that is provided at each crack initiating means.
Claim 2
Independent Claim
101 words
A device for indicating accumulated fatigue in a selected portion of a structural member, comprising an elongate foil coupon having regions that crack in response to fatigue therein, and adhesive means securely bonding the coupon to the structural member in the selected portion to transmit to the coupon any strains therein to which the structural member is subjected; a plurality of crack initiating means being provided in the coupon, and the adhesive means providing a substantially continuous bond between the structural member and the regions that crack except in a narrow unbonded area that is provided at each crack initiating means.
Claim 3
Dependent Claim
19 words
A device as in claim 1, wherein the crack initiating means are responsive to different ranges of accumulated fatigue.
Claim 4
Dependent Claim
13 words
A device as in claim 2, wherein the crack initiating means comprise slots.
Claim 5
Dependent Claim
34 words
A device as in claim 1, wherein at least one crack initiating means is responsive to a lower range of accumulated fatigue than is enough to crack the structural member in the selected portion.
Claim 6
Dependent Claim
12 words
A device as in claim 1, wherein the coupon is electrically conductive.
Claim 7
Dependent Claim
16 words
A device as in claim 5, wherein the coupon is electrically insulated from the structural member.
Claim 8
Dependent Claim
13 words
A device as in claim 5, wherein the adhesive means is electrically nonconductive.
Claim 9
Dependent Claim
20 words
A device as in claim 5, wherein the coupon comprises an electrically conductive outer layer and a nonconductive inner layer.
Claim 10
Dependent Claim
21 words
A device as in claim 5, comprising also means responsive to the electrical resistance of the coupon between predetermined locations thereon.
Claim 11
Dependent Claim
36 words
A device as in claim 9, wherein a plurality of crack initiating means are provided in the coupon in selected regions such that cracking therein substantially and progressively increases the electrical resistance between the predetermined locations.
Claim 12
Dependent Claim
36 words
A device as in claim 9, wherein rupture of regions between the predetermined locations may separate one portion of the coupon from another, and comprising also electrical resistance means connected between separable portions of the coupon.
Claim 13
Dependent Claim
21 words
A device as in claim 1, wherein the coupon has substantially the composition of the selected portion of the structural member.
Claim 14
Dependent Claim
16 words
A device as in claim 1, wherein the coupon is about 0.1 to 30 mils thick.
Claim 15
Dependent Claim
18 words
A device as in claim 1, wherein the adhesive means comprises an epoxy, a polyester, or a cyanoacrylate.
Claim 16
Dependent Claim
25 words
A device as in claim 1, wherein the width of each unbonded area is less than about 3 times the thickness of the coupon there.
Claim 17
Independent Claim
84 words
A device for indicating accumulated fatigue in a selected portion of a structural member, comprising an elongate foil coupon having regions that crack in response to fatigue therein, and adhesive means securely bonding the coupon to the structural member in the selected portion to transmit to the coupon any strains therein to which the structural member is subjected; a plurality of cracks initiating slots responsive to different ranges of accumulated fatigue being provided in the coupon, and the slots being oriented at different angles.
Claim 18
Independent Claim
84 words
A device for indicating accumulated fatigue in a selected portion of a structural member, comprising an elongate foil coupon having regions that crack in response to fatigue therein, and adhesive means securely bonding the coupon to the structural member in the selected portion to transmit to the coupon any strains therein to which the structural member is subjected; a plurality of cracks initiating slots responsive to different ranges of accumulated fatigue being provided in the coupon, and the slots being oriented at different angles.
Claim 19
Dependent Claim
18 words
A device as in claim 16, wherein a plurality of crack terminating means are provided in the coupon.
Claim 20
Dependent Claim
24 words
A device as in claim 16, wherein the adhesive means comprises a substantially uniform layer between the regions that crack and the structural member.
Claim 21
Dependent Claim
24 words
A device as in claim 16, wherein the adhesive means provides a substantially continuous bond between the structural member and the regions that crack.
Claim 22
Independent Claim
82 words
A device for indicating accumulated fatigue in a selected portion of a structural member, comprising an elongate foil coupon having regions that crack in response to fatigue therein, and adhesive means securely bonding the coupon to the structural member in the selected portion to transmit to the coupon any strains therein to which the structural member is subjected; a plurality of crack initiating slots responsive to different ranges of accumulated fatigue being provided in the coupon, and the slots having different geometries.
Claim 23
Independent Claim
82 words
A device for indicating accumulated fatigue in a selected portion of a structural member, comprising an elongate foil coupon having regions that crack in response to fatigue therein, and adhesive means securely bonding the coupon to the structural member in the selected portion to transmit to the coupon any strains therein to which the structural member is subjected; a plurality of crack initiating slots responsive to different ranges of accumulated fatigue being provided in the coupon, and the slots having different geometries.
Claim 24
Independent Claim
84 words
A device for indicating accumulated fatigue in a selected portion Of a structural member, comprising an elongate electrically conductive foil coupon having regions that crack in response to fatigue therein, and adhesive means securely bonding the coupon to the structural member in the selected portion to transmit to the coupon any strains therein to which the structural member is subjected, the adhesive means being electrically nonconductive and having nonconductive solid particles distributed in it to prevent contact between the coupon and the structural member.
Claim 25
Independent Claim
84 words
A device for indicating accumulated fatigue in a selected portion Of a structural member, comprising an elongate electrically conductive foil coupon having regions that crack in response to fatigue therein, and adhesive means securely bonding the coupon to the structural member in the selected portion to transmit to the coupon any strains therein to which the structural member is subjected, the adhesive means being electrically nonconductive and having nonconductive solid particles distributed in it to prevent contact between the coupon and the structural member.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-21 | 1977-07-23 | 1978-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-21 | 1981-07-23 | 1982-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-21 | 1985-07-23 | 1986-01-22 | $7700.00 | Window Closed / Lapsed |