Failure Survey Diagnosis of Structure for Rotating Machinery

In rotating machinery, there are not a few cases of failure of structure such as unbalance, misalignment and looseness. The failure of structure causes the secondary failures by giving too much stress to bearings. The conventional diagnostic method has measured the vibration amplitude and compared them with the alarm level. As the alarm level depends on the machine size, rotating speed and other operating conditions, we must prepare for the alarm level for each machine. The diagnostic method without using the alarm level has been expected. In this paper we propose a diagnostic algorithm using new deteriorative parameters which are obtained by both amplitude domain and frequency domain. We specified total power spectra caused by the fault as the deteriorative parameter in frequency domain, and we also specified logarithm of the RMS value of vibration velocity as the deteriorative parameter in amplitude domain. We examined this diagnostic algorithm by applying to the actual measured vibration data. Finally we described a handheld type machinery fault checker that is equipped with the diagnostic algorithm.