METHOD AND DEVICE FOR DETECTING CRACK IN AXIAL DIRECTION

Japanese Patent JPS6242030

A

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.

JPH0527650	[Name of device] AE sensor probe
JPS5914631	[Title of the Invention] An ignition timing control device of an internal-combustion engine

IMUDATSUDO IMAMU
HOOSUTO GANSAA DEIRORENJI

JP15637286A

February 24, 1987

July 04, 1986

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GEN ELECTRIC

G01H1/00; G01M99/00; G01H17/00; (IPC1-7): G01H17/00; G01M19/00

Tokunji Ikunuma

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