Abstract: A fault diagnosis apparatus comprises a vibration sensor for detecting vibration waveforms being generating by machinery or equipment, a cumulative frequency computing device for obtaining a cumulative frequency distribution curve of an absolute value of the vibration waveforms detected by the vibration sensor, a maximum value detecting device for obtaining a maximum value xp of the vibration waveforms detected by the vibration sensor, a peak ratio computing device for obtaining the peak ratio &bgr;1 of an equivalent effective value &sgr;eq in the cumulative frequency distribution curve computed by the cumulative frequency computing device to the maximum value xp computed by the maximum value detecting device, and a fault diagnosing device for diagnosing the degree of fault of the machinery or equipment from the magnitude of the peak ratio &bgr;1 computed by the peak ratio computing device.

Abstract: A method for diagnosis of a defect of an object to be inspected, such as a rotational machine, etc., by measuring a vibration generated thereby, wherein a measured signal generated by the object is detected, an amplitude probability density function of wave-form of the obtained measured signal is expanded orthogonally through a Gram-Charlier series, and the Gram-Charlier series are calculated so as to make diagnosis of defect(s) in the object to be inspected.

Abstract: A fault diagnosis apparatus comprises a vibration sensor for detecting vibration waveforms being generating by machinery or equipment, a cumulative frequency computing device for obtaining a cumulative frequency distribution curve of an absolute value of the vibration waveforms detected by the vibration sensor, a maximum value detecting device for obtaining a maximum value xp of the vibration waveforms detected by the vibration sensor, a peak ratio computing device for obtaining the peak ratio &bgr;1 of an equivalent effective value &sgr;eq in the cumulative frequency distribution curve computed by the cumulative frequency computing device to the maximum value xp computed by the maximum value detecting device, and a fault diagnosing device for diagnosing the degree of fault of the machinery or equipment from the magnitude of the peak ratio &bgr;1 computed by the peak ratio computing device.

Abstract: A hand-held vibrometer for measuring vibration at a surface of a vibrating object includes plural vibration sensors, each of which has a respective axis of measurement. The vibration sensors are mounted on a rigid body so that the respective axes of measurement of the sensors intersect at a contact point on the rigid body, which contact point is to be applied to the vibrating object. The contact point is at a central axis of the rigid body and the respective axes of measurement of the vibration sensors all intersect the central axis of the rigid body at the same angle. Respective amounts of vibration in the vibrating object in three orthogonal measurement axes are calculated on the basis of output signals provided from the plurality of vibration sensors. The above-described arrangement of the vibration sensors increases the contact resonance frequency, and consequently the measurement range, of the vibrometer.