Analyisis of Instability about the Rotor System

摘要

Based on the further analysis of traditional definition of reliability, the conception of instability degree for the rotor system had been put forward. And the probability model of instability degree for rotor system had been established by using the reliability analysis methods. After analysis of the model, the piecewise limit state equation can be obtained which use the limit of the allowed amplitude to be the threshold of piecewise interval, and then the piecewise instability probability can be calculated. To the rotor system, it is a continuous progressive process from the static state to accelerate to the normal work speed state, so can use the conditional probability form to link the each disconnected frequency bands, then based on the approach of decomposition firstly and then integration to deduce the overall instability probability formula for rotor system. By the simulation experiments, the frequency-instability curve of rotor system had been drawn, and change trend of rotor movement stability can be obtained while the rotor's frequency increasing, which is perfectly consistent with the rotor movement phenomena in the actual experiments. The analysis results can provide a certain theory and test basis for the research of rotor system instability degree.