US3875381A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stress wave emission defect location system
Assignee: National Research Development Corp UK
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Filing: 1972-05-15
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Granted: 1975-04-01
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Expires: 1992-05-15
Abstract
Abstract The invention is a system for determining the location of defects in structures, using a suitable programmed computer, in which a number of transducers are placed at different locations in the structure to pick up the bursts of stress wave emission produced by the defects and to determine the location of the defects from the differences in the times of arrival of the burst at the various transducers, the arrival of each burst being determined by a peak level sensing circuit rather than by leading edge triggering, as used in previous systems.
Inventors
- 👤 Peter Maurice Wingfield
- 👤 Roger Hill Warren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:13
CPC Classifications
G; G01; G01S; G01S3/00; G01S3/80; G01S3/802; G01S3/808; G01S1/00; G01S1/72
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
164 words
A stress wave emission defect location system for structures including transducer means coupled to the structure under test to convert said stress wave emission to electrical signals, logarithmic amplifier means joined to said transducer means to amplify said signals, circuit means coupled to said logarithmic amplifier means whereby the amplified signals initiate the gating of clock pulses from clock means into counter means, said logarithmic amplifier means including envelope (video) detector means, the outputs of said envelope (video) detector means being summed to produce a video signal whose amplitude increases with time until the stress wave emission peak is reached, sample and hold circuit means in which a sample of each cycle of the video signal is held for comparison with a proportion of the next succeeding cycle and comparator means to compare the amplitudes of successive cycles of said video signal whereby the opening of register means to accept and store the contemporary total of clock pulses in said counter means is controlled.
Claim 2
Dependent Claim
164 words
A stress wave emission defect location system for structures including transducer means coupled to the structure under test to convert said stress wave emission to electrical signals, logarithmic amplifier means joined to said transducer means to amplify said signals, circuit means coupled to said logarithmic amplifier means whereby the amplified signals initiate the gating of clock pulses from clock means into counter means, said logarithmic amplifier means including envelope (video) detector means, the outputs of said envelope (video) detector means being summed to produce a video signal whose amplitude increases with time until the stress wave emission peak is reached, sample and hold circuit means in which a sample of each cycle of the video signal is held for comparison with a proportion of the next succeeding cycle and comparator means to compare the amplitudes of successive cycles of said video signal whereby the opening of register means to accept and store the contemporary total of clock pulses in said counter means is controlled.
Claim 3
Dependent Claim
32 words
A stress wave emission defect location system as claimed in claim 1 including a plurality of register means, each of said register means relating to one transducer means location on said structure.
References Cited (Backward Citations)
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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) | 1978-03-31 | 1978-09-30 | 1979-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-31 | 1982-09-30 | 1983-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-31 | 1986-09-30 | 1987-04-01 | $7700.00 | Window Closed / Lapsed |