Performance degradation assessment has emerged to realize equipment’s near-zero downtime and maximum productivity. Exploring effective indices is crucial for it. In this study, taking rolling element bearing as a research object, cyclic energy indicator is proposed for its performance degradation assessment. The proposed cyclic energy indicator is based on signals’ cyclic coherence analysis and its variation with the damage extent of the rolling element bearing is verified through simulation and seeded fault experimental data. Then an accelerated life test of the rolling element bearing is performed to collect vibration data over the whole life time (normal-fault-failure). Results of both simulation and experiments show that the cyclic energy indicator is an effective index for the degradation assessment of rolling element bearings.
A finite element (FE) model, which is based on a transfer matrix analysis and local flexibility theorem, is introduced for crack identification of a static (non-rotating) rotor with an open crack. Through numerical simulation, the effects of crack location and crack depth on the mode shapes and the changes in the eigenfrequencies of the cracked rotor are investigated. A crack identification algorithm that makes use of the translations of the first mode at two symmetric points and the contour diagram of crack location versus crack depth for the first two given normalized eigenfrequencies is proposed to estimate the crack location and depth in the rotor. Two illustrative examples are demonstrated and compared for availability and validity of the proposed algorithm.
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