Boots – shoes – and leggings
Patent
1985-07-08
1988-06-14
Lall, Parshotam S.
Boots, shoes, and leggings
364507, 364552, 73577, G01M 700
Patent
active
047516577
ABSTRACT:
Axial cracks in the rotor assembly of a variety of rotating machinery are detected while the rotor is being rotated, by sensing mechanical vibrations of the rotor at a location along the length thereof to produce a corresponding rotor vibration signal. A background vibration signal representing the vibration response at an earlier time is provided, as well as a monitor vibration signal representing the vibration response of the rotor at the time the monitor signal is obtained. A speed-dependent first harmonic difference signal is found by vectorially subtracting the first harmonic of the background vibration signal from the first harmonic of the monitor vibration signal. The relationship between the amplitude of the difference signal and the rotational speed of the rotor is then determined for rotational speeds away from the speed at which vibrational resonance occurs, with a relationship wherein the difference signal is proportional to the fourth power of the rotational speed being indicative of the presence of an axial crack in the rotor assembly. Histogram techniques improve the signal-to-noise ratio of the background vibration signal and of the monitor vibration signal. The vibration response of the rotor assembly at rotational speeds near the resonance speed may be utilized in conjunction with the response at speeds away from the resonance speed, in order to confirm the presence of a rotor crack.
REFERENCES:
patent: 3713127 (1973-01-01), Keledy et al.
patent: 4007630 (1977-02-01), Noda
patent: 4380172 (1983-04-01), Imam et al.
patent: 4408294 (1983-10-01), Imam
patent: 4635210 (1987-01-01), Shiohata et al.
"Crack Propagation Testing Machine Using Shimadzu Servopulser Dynatec", Fujimoto et al., Shimadzu Corp., Kyoto, Japan, Jun. 11, 1979, pp. 43-48.
"Load Fatigue Testing: State of the Art Survey", S. R. Swanson, Materials Research & Standards, Apr. 1963, pp. 11-44.
DeLorenzi Horst G.
Imam Imdad
Davis Jr. James C.
General Electric Company
Lall Parshotam S.
Steinberg William H.
Trans V. N.
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