US4304135A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Constraint factor for structural monitoring
Assignee: ConocoPhillips Co
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Filing: 1980-04-16
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Granted: 1981-12-08
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Expires: 2000-04-16
Abstract
Abstract A dual element strain gauge is placed near a welded or otherwise constrained joint on a structural member so as to provide a constraint factor. The location for the strain gauge must be selected to provide constraint factor that is preferably near either maximum or minimum value. The strain gauge is monitored to detect a change in the initial constraint factor, which indicates failure has begun or is imminent.
Inventors
- 👤 Marvin L. Peterson
- 👤 Norman W. Hein, Jr.
- 👤 Donald H. Oertle
- 👤 Steven E. Hawkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:28
CPC Classifications
G; G01; G01M; G01M5/00; G01M5/0033; G01L; G01L1/00; G01L1/20; G01L1/22; G01N; G01N3/00; G01N2203/00; G01N2203/0058; G01N2203/006; G01N2203/0062; G01N2203/0064; G01N2203/0066; G01N2203/02; G01N2203/026; G01N2203/0296
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
118 words
A method for predicting structural failure and detecting axial failure in constrained structural members subject to fatigue and static stress comprising (a) placing at least one dual element strain gauge near a structural constraint, said strain gauge having one element extending substantially parallel to the longitudinal axis of the structural member to record longitudinal strain, and the second element extending substantially perpendicular to said first element to record transverse strain, wherein said placement is determined by a maximum or minimum reading from either element of said gauge; (b) calculating a constraint factor of said structural member by determining the ratio of longitudinal strain to transverse strain, then (c) monitoring said factor for change, said change indicating structural failure.
Claim 2
Independent Claim
118 words
A method for predicting structural failure and detecting axial failure in constrained structural members subject to fatigue and static stress comprising (a) placing at least one dual element strain gauge near a structural constraint, said strain gauge having one element extending substantially parallel to the longitudinal axis of the structural member to record longitudinal strain, and the second element extending substantially perpendicular to said first element to record transverse strain, wherein said placement is determined by a maximum or minimum reading from either element of said gauge; (b) calculating a constraint factor of said structural member by determining the ratio of longitudinal strain to transverse strain, then (c) monitoring said factor for change, said change indicating structural failure.
Claim 3
Dependent Claim
16 words
A method as described in claim 1 wherein the structural members are comprised of metallic members.
Claim 4
Dependent Claim
20 words
A method as described in claim 2 wherein a plurality of dual element strain gauges are placed on structural members.
Claim 5
Dependent Claim
21 words
A method as described in claim 3 wherein strain gauges are positioned on structural members in the area of highest constraint.
Claim 6
Dependent Claim
14 words
A method as described in claim 3 wherein said strain gauges are monitored continuously.
Claim 7
Dependent Claim
17 words
A method as described in claim 5 wherein constraint factors are continuously compared to original constraint factors.
Claim 8
Dependent Claim
24 words
A method as described in claim 6 wherein the strain gauges are placed from 1 to 2 structural member diameters from the constrained area.
Claim 9
Dependent Claim
13 words
A method as described in claim 7 wherein the structural members are welded.
Claim 10
Dependent Claim
13 words
A method as described in claim 7 wherein the structural members are bolted.
Claim 11
Dependent Claim
18 words
A method as described in claim 7 wherein the strain gauges are protected from the structural member environment.
Claim 12
Dependent Claim
22 words
A method as described in claim 7 wherein the only one dual element strain gauge is monitored for change in constraint factor.
Claim 13
Dependent Claim
17 words
A method as described in claim 7 wherein crack growth is monitored by comparing constraint factor change.
Claim 14
Dependent Claim
20 words
A method as described in claim 7 wherein structural integrity is monitored with sensing elements remote from areas of failure.
Claim 15
Dependent Claim
20 words
A method as described in claim 7 wherein the constraint factor change of 50% or more will signal an alarm.
Claim 16
Dependent Claim
17 words
A method as described in claim 14 wherein the structural member is part of an offshore platform.
Claim 17
Dependent Claim
15 words
A method as described in claim 1 wherein the structural members are comprised of fiberglass.
Claim 18
Dependent Claim
15 words
A method as described in claim 1 wherein the structural members are comprised of wood.
Claim 19
Dependent Claim
15 words
A method as described in claim 1 wherein the structural members are comprised of concrete.
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) | 1984-12-07 | 1985-06-08 | 1985-12-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-12-07 | 1989-06-08 | 1989-12-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-12-07 | 1993-06-08 | 1993-12-08 | $7700.00 | Window Closed / Lapsed |