Application of time-frequency analysis to machinery condition assessment

Machinery condition has traditionally been assessed by analysis of the spectral energy density of the machine´s vibration signal. Examination of time-frequency representations (TFRs) of constant-speed machinery data reveals vibration features that demonstrate variation in frequency over a short time period and thus cannot be adequately characterized by the power spectrum. These features may be used as supplemental information to assess the condition of the machine. Although the spectrogram provides a general indication of the time-varying spectrum, new representations such as the “cone-kernel” TFR reveal the existence of fine structural details inherent to the signal