US4041377A
Expired / Lapsed
US
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Magnetostriction testing apparatus having digital output display
Assignee: Armco Inc
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Filing: 1976-08-25
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Granted: 1977-08-09
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Expires: 1996-08-25
Abstract
Abstract A method and apparatus for providing a digital display representing the magnetostrictive characteristics of a test specimen is disclosed. The apparatus is useful in combination with a test fixture of the type having means for inducing a periodic and alternating induction in a test specimen and including at least one displacement sensitive transducer mounted in association with the test specimen for generating a magnetostriction signal reflecting the magnetostrictive deformation of the test specimen in response to the induction. The apparatus includes a timing circuit associated with the means for inducing the induction in the test specimen, the timing circuit being adapted for producing a series of timing signals identifying the occurrences of zero and maximum induction in the specimen. A conversion circuit operates under the control of the timing circuit for deriving from the magnetostriction signal a DC difference signal which is proportional to the difference between the amplitudes of the magnetostriction signal corresponding to the occurrences of maximum and zero induction in the test specimen. The DC difference signal, which reflects the magnetostrictive characteristics of the test specimen, is applied to a display which produces a digital output corresponding to the magnitude and polarity of the DC difference signal.
Inventors
- 👤 Richard F. Lyke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 11:03
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/12; G01R33/18
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
166 words
In a magnetostriction testing apparatus of the type having means for inducing an alternating and periodic induction in a test specimen and having at least one displacement sensitive transducer mounted in association with said test specimen for generating a magnetostriction signal representative of the magnetostrictive deformation of said test specimen in response to said induction, the improvement comprising: a. a timing circuit in association with said means for inducing said induction for developing a plurality of timing signals, some at least of said timing signals having logical transitions corresponding to the occurrences of zero and maximum induction in said test specimen; b. a conversion circuit responsive to said timing signals for generating from said magnetostriction signal a DC difference signal proportional to the difference between the amplitudes of said magnetostriction signal corresponding to the occurrences of maximum and zero induction in said test specimen, and c. means responsive to said conversion circuit for producing a display reflecting the magnitude and polarity of said DC difference signal.
Claim 2
Dependent Claim
166 words
In a magnetostriction testing apparatus of the type having means for inducing an alternating and periodic induction in a test specimen and having at least one displacement sensitive transducer mounted in association with said test specimen for generating a magnetostriction signal representative of the magnetostrictive deformation of said test specimen in response to said induction, the improvement comprising: a. a timing circuit in association with said means for inducing said induction for developing a plurality of timing signals, some at least of said timing signals having logical transitions corresponding to the occurrences of zero and maximum induction in said test specimen; b. a conversion circuit responsive to said timing signals for generating from said magnetostriction signal a DC difference signal proportional to the difference between the amplitudes of said magnetostriction signal corresponding to the occurrences of maximum and zero induction in said test specimen, and c. means responsive to said conversion circuit for producing a display reflecting the magnitude and polarity of said DC difference signal.
Claim 3
Dependent Claim
21 words
The improvement according to claim 1 wherein said means responsive to said conversion circuit comprises means for producing a digital display.
Claim 4
Dependent Claim
31 words
The improvement according to claim 2 including means connected intermediate said transducer and said conversion circuit for amplifying said magnetostriction signal and including means for filtering the low frequency noise therefrom.
Claim 5
Dependent Claim
127 words
The improvement according to claim 3 wherein said conversion circuit comprises: a. a first data channel connected for receiving said amplified magnetostriction signal and including means for developing a first DC output signal proportional to the amplitude of said magnetostriction signal corresponding to the occurrences of maximum induction in said test specimen; b. a second data channel connected for receiving said amplified magnetostriction signal and including means for developing a second DC output signal proportional to the amplitude of said magnetostriction signal corresponding to the occurrences of zero induction in said test specimen; and c. a differential amplifier connected for generating an output comprising said second DC output signal subtracted from said first DC output signal, said output of said differential amplifier comprising said DC difference signal.
Claim 6
Dependent Claim
128 words
The improvement according to claim 4 wherein said means for amplifying includes means for inverting said magnetostriction signal and wherein said timing circuit comprises means for generating a first timing signal characterized by a first logical condition between all occurrences of zero induction and their respective immediately succeeding occurrences of maximum induction in said test specimen and otherwise characterized by a second logical condition, said timing circuit further including means for generating a second timing signal comprising the complement of said first timing signal and means for generating third and fourth timing signals comprising, respectively, trains of relatively short duration logic pulses at said first logical condition and occurring substantially immediately succeeding each transition from said first to second logical condition of said first and second timing signals.
Claim 7
Dependent Claim
158 words
The improvement according to claim 5 wherein said first and second data channels each comprise an input sample and hold amplifier responsive to, respectively, said first and second timing signals and each having an input connected for receiving said amplified and inverted magnetostriction signal, said first and second data channels each further comprising an output sample and hold amplifier responsive to, respectively, said third and fourth timing signals and each having an input connected for receiving the output of its respective input sample and hold amplifier, each of said sample and hold amplifiers being operative for causing its output to track its input only so long as its associated timing signal is characterized by said first logical condition and to otherwise hold its output at the last tracked value of its input, whereby the outputs of said output sample and hold amplifiers of said first and second data channels comprise, respectively, said first and second DC output signals.
Claim 8
Independent Claim
105 words
The method of generating a digital display representing the magnetostrictive characteristics of a test specimen comprising the steps of: a. inducing a periodic and alternating induction in said test specimen; b. generating a magnetostriction signal representative of the magnetostrictive deformation of said test specimen in response to said induction; c. simultaneously developing first and second output signals reflecting, respectively, the amplitudes of said magnetostriction signal at the occurrences of maximum and zero induction in said test specimen; d. subtracting said second output signal from said first output signal to provide a difference signal; and e. digitally displaying the polarity and magnitude of said difference signal.
Claim 9
Independent Claim
105 words
The method of generating a digital display representing the magnetostrictive characteristics of a test specimen comprising the steps of: a. inducing a periodic and alternating induction in said test specimen; b. generating a magnetostriction signal representative of the magnetostrictive deformation of said test specimen in response to said induction; c. simultaneously developing first and second output signals reflecting, respectively, the amplitudes of said magnetostriction signal at the occurrences of maximum and zero induction in said test specimen; d. subtracting said second output signal from said first output signal to provide a difference signal; and e. digitally displaying the polarity and magnitude of said difference signal.
Claim 10
Dependent Claim
116 words
The method according to claim 7 wherein said step of developing said first and second output signals comprises the steps of: a. developing an intermediate signal by tracking said magnetostriction signal between each occurrence of zero induction in said test specimen and the immediately succeeding occurrence of maximum induction in said test specimen and holding the last tracked value thereof until the next occurrence of zero induction in said test specimen; and b. developing said first signal by tracking, for a relative short time period following each occurrence of maximum induction in said test specimen, said intermediate signal and holding the last tracked value thereof until the next occurrence of maximum induction in said test specimen.
Claim 11
Dependent Claim
117 words
The method according to claim 7 wherein said step of developing said first and second output signals comprises the steps of: a. developing an intermediate signal by tracking said magnetostriction signal between each occurrence of maximum induction in said test specimen and the immediately succeeding occurrence of zero induction in said test specimen and holding the last tracked value thereof until the next occurrence of maximum induction in said test specimen; and b. developing said second output signal by tracking, for a relatively short time period following each occurrence of zero induction in said test specimen, said intermediate signal and holding the last tracked value thereof until the next occurrence of zero induction in said test specimen.
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) | 1980-08-08 | 1981-02-07 | 1981-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-08 | 1985-02-07 | 1985-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-08 | 1989-02-07 | 1989-08-09 | $7700.00 | Window Closed / Lapsed |