| 摘要 |
The method uses records from a BTT system and involves their further processing. The discrete Fourier transform produces aliased amplitude spectra in frequency bands (-∫ N , +∫ N ). Resonance bands of aliased amplitude spectra are then transferred, while respecting the polarity, to reconstructed spectra of individual blades within the (-∫ R , +∫ R ) interval, where fa is half the sampling frequency of the reconstructed spectrum. The inverse Fourier transform yields reconstructed profiles of the original signals of rotating blades vibration in the tangential direction. From the reconstructed profiles of signals, stress tensors are determined and, from those, the effective damaging stress is found. From this stress value, damage increments caused by sequences of extrema of time series of damaging stresses decomposed by the rainflow counting technique are determined and accumulated separately for each individual blade, After the resonance bands were transferred to the reconstructed Fourier spectrum, the remainder of the aliased Fourier spectrum can be distributed across the reconstructed Fourier spectrum. Where multiple probes are used in the BTT system, the records are evaluated for each of the probes. The data from the probe which represents the largest damage increment will be used for evaluating the accumulated damage. |
