Development of a degradation index for machinery condition monitoring using the fictitious frequency response function and its application to a entrifugal compressor

摘要

Recently, many sophisticated machinery diagnosis techniques have been developed and incorporated to the condition-based maintenance (CBM) methodrnfor cost effective and reliable operation of machinery. However, many companies are still reluctant to change their maintenance strategy completely fromrnthe traditional time-based maintenance (TBM) method to the CBM method due to their conservative approach. Instead, they often want to reduce thernmaintenance cost by increasing the time between overhaul (TBO) provided that a machine under inspection has not been degraded too much. In order tornmeet this need, in this paper, a degradation index is suggested as a measure to evaluate how much a machine has been degraded since its last overhaulrnservice. The proposed degradation index is based on the fictitious frequency response function method. It is simple to interpret, and has a clear physicalrnmeaning. It is applied to an integrally geared centrifugal compressor and validated its usefulness. The results show that the suggested degradation index canrnbe used as a good complement to both the TBM and CBM methods.