STRUCTURAL HEALTH MONITORING FOR ROTATING IMBALANCE AND MISALIGNMENT

摘要

The dynamics of rotating machinery are dominated by responses due to shaft and drive train characteristics such as imbalance, misalignment, gear mesh, and bearings. These phenomena occur a fixed number of times every revolution, and are related to rotational speed. This paper presents a new method for condition monitoring of such phenomena. An autoregressive model used for condition assessment is fit to the pulse signal. Decomposition of the model yields its characteristic roots, which contain the frequency, damping value, and variance of the signal component. The model also provides an analytical spectrum yielding clear spectral peaks with extremely accurate levels. The illustrated results are based on an experiment built to simulate a rotating imbalance, shaft misalignment, or a combination of the two. Three areas of improvement are identified. The first is characterization of extra information in the speed signal, eliminating the need for an added measurement that must be related to the speed. The second development is a single number estimate of energies at defect frequencies, eliminating subjective interpretation of spectral plots. The third enhancement is the technique's ability to make accurate spectral estimates based on limited data, allowing the technician to handle situations where rapid speed changes are unavoidable.