Patent US4574642A successfully refreshed from Google Patents.
US4574642A
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Apparatus for automated crack growth rate measurement
Assignee: Bridgestone Firestone Inc
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Filing: 1984-11-23
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Granted: 1986-03-11
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Expires: 2004-11-23
Abstract
Abstract Apparatus for monitoring and measuring the growth of a crack in an elastic specimen. The specimen is repeatedly flexed by a piston at a set frequency and periodically slowed to a substantially lower frequency during which time a line scan camera monitors the length of the crack. The camera is positioned such that the specimen is drawn through the scan line thereof. The camera is calibrated such that the output signal from the camera correlates directly to the cracklength. This output signal is digitized, received, and stored by a digital processor for use in determining the crack growth rate.
Inventors
- 👤 Thomas S. Fleischman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 08:26
CPC Classifications
G; G01; G01N; G01N3/00; G01N3/32; G01N19/00; G01N19/08; G01N2203/00; G01N2203/0014; G01N2203/0023; G01N2203/0058; G01N2203/006; G01N2203/0062; G01N2203/0066
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
109 words
Apparatus for monitoring the growth of a crack in a first edge of an elastic specimen, comprising: first means for receiving and flexing the specimen; second means in juxtaposition to said first means for optically viewing the specimen in an area including the crack and generating an output signal, said second means comprising a line scan camera and said output signal being a function of the contrast between light and dark in a scan line of said camera, said scan line extending beyond at least the first edge of the specimen; and third means connected to said second means for collecting and storing data obtained from said output signal.
Claim 2
Dependent Claim
109 words
Apparatus for monitoring the growth of a crack in a first edge of an elastic specimen, comprising: first means for receiving and flexing the specimen; second means in juxtaposition to said first means for optically viewing the specimen in an area including the crack and generating an output signal, said second means comprising a line scan camera and said output signal being a function of the contrast between light and dark in a scan line of said camera, said scan line extending beyond at least the first edge of the specimen; and third means connected to said second means for collecting and storing data obtained from said output signal.
Claim 3
Dependent Claim
29 words
The apparatus according to claim 1 wherein said first means comprises a reciprocating piston receiving a first end of the specimen and a load cell receiving a second end.
Claim 4
Dependent Claim
29 words
The apparatus according to claim 1 wherein said third means comprises a digital processor having a memory, said memory receiving and storing said data obtained from said output signal.
Claim 5
Dependent Claim
32 words
The apparatus according to claim 3 wherein said third means further comprised an analog to digital converter interposed between said line scan camera and said digital process for digitizing said output signal.
Claim 6
Dependent Claim
27 words
The apparatus according to claim 1 wherein said third means is further operatively connected to said first means for controlling the amplitude and frequency of said flexing.
Claim 7
Dependent Claim
21 words
The apparatus according to claim 5 wherein said third means is selectively enabled to receive said data from said output signal.
Claim 8
Dependent Claim
22 words
The apparatus according to claim 6 wherein said third means is enabled for a full cycle of said flexing at periodic intervals.
Claim 9
Dependent Claim
22 words
The apparatus according to claim 7 wherein said data is received from said output signal during one half of said full cycle.
Claim 10
Dependent Claim
79 words
Apparatus for monitoring the growth of a crack propagating from the edge of an elastic specimen, comprising: reciprocating means for receiving and flexing the specimen; a line scan camera maintained opposite said reciprocating means and having a scan line extending beyond the edge of the specimen from which the crack propagates; and processing means connected to said reciprocating means and said camera for controlling the frequency at which the specimen is flexed and periodically receiving data from said camera.
Claim 11
Dependent Claim
79 words
Apparatus for monitoring the growth of a crack propagating from the edge of an elastic specimen, comprising: reciprocating means for receiving and flexing the specimen; a line scan camera maintained opposite said reciprocating means and having a scan line extending beyond the edge of the specimen from which the crack propagates; and processing means connected to said reciprocating means and said camera for controlling the frequency at which the specimen is flexed and periodically receiving data from said camera.
Claim 12
Dependent Claim
27 words
The apparatus according to claim 9 wherein said camera is fixedly positioned and said scan line is orthogonal to an axis along which said specimen is flexed.
Claim 13
Dependent Claim
19 words
The apparatus according to claim 10 wherein said flexing of the specimen draws the crack through said scan line.
Claim 14
Dependent Claim
32 words
The apparatus according to claim 10 wherein said reciprocating means comprises a piston maintained in juxtaposition to a load cell, the specimen being received and maintained between said piston and load cell.
Claim 15
Dependent Claim
39 words
The apparatus according to claim 10 wherein said processing means maintains said reciprocating means at a fixed frequency, periodically interrupting said frequency with a reduced frequency, said processing means receiving said data from said camera during said reduced frequency.
Claim 16
Dependent Claim
41 words
The apparatus according to claim 13 wherein said processing means comprises a digital processor, and wherein said camera emits an analog output signal corresponding to the contrast between light and dark along said scan line on each scan of the camera.
Claim 17
Dependent Claim
24 words
The apparatus according to claim 14 wherein said processing means further comprises an analog to digital converter, receiving and digitizing said analog output signal.
Claim 18
Dependent Claim
21 words
The apparatus according to claim 9 which further includes a light source positioned opposite said camera with the specimen interposed therebetween.
Claim 19
Dependent Claim
20 words
The apparatus according to claim 16 wherein said light source is connected to, and selectively energized by, said processing means.
References Cited (Backward Citations)
US3918299A
Cited
US3983745A
Cited
US4003246A
Cited
US4175447A
Cited
GB2057124A
Cited
US4418563A
Cited
GB2108684A
Cited
JPS58211626A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-03-10 | 1989-09-09 | 1990-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-10 | 1993-09-09 | 1994-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-10 | 1997-09-09 | 1998-03-11 | $7700.00 | Window Closed / Lapsed |