US3681970A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of flaw detection using internal heating
Assignee: G C OPTRONICS Inc
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Filing: 1970-03-09
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Granted: 1972-08-08
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Expires: 1990-03-09
Abstract
Abstract A method and apparatus are disclosed for nondestructive testing for subsurface flaws in a workpiece. The surface configuration of the workpiece is recorded and heat is induced in the interior of a discrete volume of the material. Then the surface configuration of the workpiece is compared during the dispersion of heat from the discrete volume with the recorded surface configuration to reveal differences as an indication of a flaw. The heating of the interior material is accomplished by producing electrical currents therein as by induction heating. The comparison of the surface configuration during the dispersion of heat with the recording of the surface configuration is preferably accomplished by the use of holographic interferometry.
Inventors
- 👤 Donald R Wells
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:58
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/021; G01N; G01N25/00; G01N25/72; Y; Y10; Y10S; Y10S359/00; Y10S359/90; Y10S359/902
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
93 words
The method of detecting subsurface flaws in a member comprising the steps of; recording a pictorial representation of the surface configuration of a selected portion of the member, inducing internally generated heat by inducing electrical currents in the interior of a discrete volume of the member adjacent the selected portion, and interferometrically comparing the surface configuration of the selected portion during the dispersion of heat from the discrete volume with the recording of the pictorial representation of the surface configuration to identify areas of differential change of configuration as an indication of flaws.
Claim 2
Independent Claim
93 words
The method of detecting subsurface flaws in a member comprising the steps of; recording a pictorial representation of the surface configuration of a selected portion of the member, inducing internally generated heat by inducing electrical currents in the interior of a discrete volume of the member adjacent the selected portion, and interferometrically comparing the surface configuration of the selected portion during the dispersion of heat from the discrete volume with the recording of the pictorial representation of the surface configuration to identify areas of differential change of configuration as an indication of flaws.
Claim 3
Independent Claim
114 words
The method of detecting subsurface flaws in materials comprising the steps of; making a hologram of a selected portion of the surface of the material; illuminating the hologram to reconstruct the wavefront to form an image of the selected portion of said surface, superposing the image on said selected portion of said surface, inducing internally generated heat in the interior of a discrete volume of the material adjacent the selected portion whereby the wavefront from the selected portion of said surface and the reconstructed wavefront from the hologram interfere to form a pattern of interference fringes indicative of differential change of configuration of the selected portion of said surface as an indication of flaws.
Claim 4
Independent Claim
114 words
The method of detecting subsurface flaws in materials comprising the steps of; making a hologram of a selected portion of the surface of the material; illuminating the hologram to reconstruct the wavefront to form an image of the selected portion of said surface, superposing the image on said selected portion of said surface, inducing internally generated heat in the interior of a discrete volume of the material adjacent the selected portion whereby the wavefront from the selected portion of said surface and the reconstructed wavefront from the hologram interfere to form a pattern of interference fringes indicative of differential change of configuration of the selected portion of said surface as an indication of flaws.
Claim 5
Dependent Claim
34 words
The invention as defined in claim 1 wherein the step of inducing heat in the discrete volume is performed by electrical induction heating with an induction coil disposed adjacent the surface of the material.
Claim 6
Dependent Claim
30 words
The invention as defined in claim 1 wherein the induction heating is produced by an induction coil having turns which define an opening opposite said selected portion of the material.
Claim 7
Dependent Claim
83 words
The invention as defined in claim 4 wherein said induction heating is produced by applying impulses of electrical energization to the induction coil at spaced time intervals, the step of comparing the surface configurations is performed throughout the time of application of several impulses and wherein the frequency of said electrical energization of the induction coil is low enough to obtain the induction of eddy currents internally of said volume of material but high enough to achieve a high rate of internal heating.
Claim 8
Independent Claim
90 words
The method of detecting subsurface flaws in materials comprising the steps of; making a hologram of a selected portion of the surface of the material, inducing internally generated heat in the interior of a discrete volume of the material adjacent the selected portion, making a second hologram of the selected portion of the surface of the material; illuminating said holograms to reconstruct the wavefronts to produce an image of the surface with a pattern of interference fringes thereon indicative of areas differential change of configuration as an indication of flaws.
Claim 9
Independent Claim
90 words
The method of detecting subsurface flaws in materials comprising the steps of; making a hologram of a selected portion of the surface of the material, inducing internally generated heat in the interior of a discrete volume of the material adjacent the selected portion, making a second hologram of the selected portion of the surface of the material; illuminating said holograms to reconstruct the wavefronts to produce an image of the surface with a pattern of interference fringes thereon indicative of areas differential change of configuration as an indication of flaws.
Claim 10
Dependent Claim
34 words
The invention as defined in claim 6 wherein the step of inducing heat in the discrete volume is performed by electrical induction heating with an induction coil disposed adjacent the surface of the material.
Claim 11
Dependent Claim
30 words
The invention as defined in claim 6 wherein the induction Heating is produced by an induction coil having turns which define an opening opposite said selected portion of the material.
Claim 12
Dependent Claim
83 words
The invention as defined in claim 8 wherein said induction heating is produced by applying impulses of electrical excitation to the induction coil at spaced time intervals, the step of comparing the surface configurations is performed throughout the time of application of several impulses and wherein the frequency of said electrical energization of the induction coil is low enough to obtain the induction of eddy currents internally of said volume of material but high enough to achieve a high rate of internal heating.
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) | 1975-08-08 | 1976-02-07 | 1976-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-08 | 1980-02-07 | 1980-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-08 | 1984-02-07 | 1984-08-08 | $7700.00 | Window Closed / Lapsed |