P.D. McFadden

A technique for calculating the time domain averages of the vibration of the individual planet gears and the sun gear in an epicyclic gearbox

Abstract A technique is presented for the calculation of the time domain averages of the tooth meshing vibration of the individual planet gears and of the sun gear in an epicyclic gearbox. A detailed analysis is given to establish the conditions under which the technique may be applied.

Interpolation techniques for time domain averaging of gear vibration

Abstract Interpolation by digital computer provides an alternative to the phase-locked frequency multiplier for the calculation of the time domain average of gear vibration signals. Higher-order interpolation techniques produce flatter passbands and lower sidelobes in the stopband but require longer calculation times. Aliasing errors are introduced into the result by replication of the sidelobes during interpolation, but in general are attenuated by time domain averaging.

Determining the location of a fatigue crack in a gear from the phase of the change in the meshing vibration

Abstract An existing digital signal processing technique for calculating the amplitude and phase modulation of the tooth meshing vibration of a gear from the time domain average of the vibration is extended so that the amplitude and phase of the changes in the vibration due to a fatigue crack in a tooth may be determined. A simple explanation is proposed whereby the phase angle of the change in the vibration may be directly related to the location in the tooth of the fatigue crack.

Decomposition of gear motion signals and its application to gearbox diagnostics

The decomposition of gear motion and the related dynamic measurements for the condition monitoring and fault diagnosis of gearboxes are described. The motion error signal is separated according to fundamental frequencies into the harmonic error and the residual error, which are used to quantify the gear condition. High-order accelerations, such as jerk, are considered and shown to be more sensitive to some classes of early damage to gear teeth. Analysis of the time domain average of a gearbox casing vibration signal enables early detection of gear damage. Several methods to represent and enhance the fault information in the signal are introduced, based on the representation of different forms of the motion errors