US3774443A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic emission damage measurement
Assignee: LGB Inc
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Filing: 1972-06-19
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Granted: 1973-11-27
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Expires: 1992-06-19
Abstract
Abstract A precracked gage element is attached to a structural member to be monitored for damage and is continuously or periodically monitored to determine acoustic emission therefrom as a measure of fatigue damage of a structural member.
Inventors
- 👤 A Green
- 👤 W Creek
- 👤 A Tetelman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 01:49
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/14; G01B; G01B17/00; G01B17/04
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
89 words
A method of measuring fatigue damage of a structural member comprising the steps of forming an indentation in an edge of a flat piece of gage material, attaching said piece of gage material to a structural member, and at least periodically monitoring said piece of gage material for acoustic emission while applying an increasing force to the piece and measuring the applied force at initiation of acoustic emission, whereby the difference in said measured force and initial known force is a measure of fatigue damage of said structural member.
Claim 2
Independent Claim
89 words
A method of measuring fatigue damage of a structural member comprising the steps of forming an indentation in an edge of a flat piece of gage material, attaching said piece of gage material to a structural member, and at least periodically monitoring said piece of gage material for acoustic emission while applying an increasing force to the piece and measuring the applied force at initiation of acoustic emission, whereby the difference in said measured force and initial known force is a measure of fatigue damage of said structural member.
Claim 3
Dependent Claim
39 words
The method of claim 1 further defined by initially stressing said piece of gage material a predetermined amount by applying a known force thereto whereby said material does not produce acoustic emission at stresses less than said initial stress.
Claim 4
Dependent Claim
83 words
The method of claim 1 further defined by forming the indentation in the edge of said piece of gage material with a pointed inner end to thus concentrate stress at such point whereby the repeated application of forces to the piece of gage material attached to the structural member causes minute cracking at the point of the indentation to thus change the stress concentration thereat with similar force application so that acoustic emission occurs at a lower force than the initial known force.
References Cited (Backward Citations)
DE852771C
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-26 | 1977-05-28 | 1977-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-26 | 1981-05-28 | 1981-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-26 | 1985-05-28 | 1985-11-27 | $7700.00 | Window Closed / Lapsed |