Electricity: measuring and testing – Magnetic – Stress in material measurement
Patent
1996-05-08
1997-04-01
Strecker, Gerard R.
Electricity: measuring and testing
Magnetic
Stress in material measurement
324225, 324240, 324241, 324262, G01N 2790, G01R 3312
Patent
active
056170246
ABSTRACT:
A flux-focusing electromagnetic sensor which uses a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks and material loss in high conductivity material. The unique feature of the device is the ferrous shield isolating a high-turn pick-up coil from an excitation coil. The use of the magnetic shield is shown to produce a null voltage output across the receiving coil in the presence of an unflawed sample. A redistribution of the current flow in the sample caused by the presence of flaws, however, eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal.
The maximum sensor output is obtained when positioned symmetrically above the crack. Hence, by obtaining the position of the maximum sensor output, it is possible to track the fault and locate the area surrounding its tip. The accuracy of tip location is enhanced by two unique features of the sensor; a very high signal-to-noise ratio of the probe's output which results in an extremely smooth signal peak across the fault, and a rapidly decaying sensor output outside a small area surrounding the crack tip which enables the region for searching to be clearly defined. Under low frequency operation, material thinning due to corrosion damage causes an incomplete shielding of the pick-up coil. The low frequency output voltage of the probe is therefore a direct indicator of the thickness of the test sample.
REFERENCES:
patent: 2790140 (1957-04-01), Bender
patent: 2965840 (1960-12-01), Renken, Jr. et al.
patent: 3229197 (1966-01-01), Renken, Jr.
patent: 3427872 (1969-02-01), Leep et al.
patent: 3495166 (1970-02-01), Lorenzi et al.
patent: 3532969 (1970-10-01), McCullough et al.
patent: 3662576 (1972-05-01), Girlatschek
patent: 4207519 (1980-06-01), Zatsepin et al.
patent: 4234848 (1980-11-01), Diem et al.
patent: 4437062 (1984-03-01), Donnelly
patent: 4651093 (1987-03-01), Detriche et al.
patent: 4689558 (1987-08-01), Ruuskanen et al.
patent: 4788499 (1988-11-01), Meier et al.
patent: 4799010 (1989-01-01), Muller
patent: 4821204 (1989-04-01), Huschelrath
patent: 4855677 (1989-08-01), Clark, Jr. et al.
patent: 5021738 (1991-06-01), Vernon et al.
patent: 5028100 (1991-07-01), Valleau et al.
patent: 5053705 (1991-10-01), Herko
patent: 5115196 (1992-05-01), Low et al.
patent: 5202623 (1993-04-01), LePage
patent: 5432444 (1995-07-01), Yasohoma et al.
T. E. Capobianco, "Real-time eddy current monitoring of fatigue crack growth"; Rev. Progress in Quantitative NDE, vol. 11, ed. D.O. Thompson and D.E. Chimenti, Plenium Press, NY, pp. 2117-2122.
Clendenin C. Gerald
Fulton James P.
Namkung Min
Nath Shridhar C.
Simpson John W.
Edwards Robin W.
Strecker Gerard R.
The United States of America as represented by the United States
LandOfFree
Flux focusing eddy current probe does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flux focusing eddy current probe, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flux focusing eddy current probe will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-542211