Some problems with vibration-based health monitoring
Abstract
Integration of the Russian scientific and technological achievements with similar foreign developments caused a conflict of interest and misunderstanding, particularly, in the machinery condition monitoring, diagnostics and health monitoring. The conflict of interest is primarily associated with the commercial interest of certain firms and companies aimed at selling their products and the related intentional and unintentional misconception in the machinery diagnostics. The misunderstanding relates to the lag of foreign countries in some fields of science and technology, specifically, in machinery vibroacoustic diagnostics and health monitoring.
The purpose of the paper is to present the basic terminology of diagnostics, monitoring and vibroacoustics and its application to the real engineering solutions.
The terminology is suggested by guidelines and regulations, reference, scientific and educational materials, including the researches carried out by the authors.
The analysis of the terminology used in Russia and abroad revealed the differing interpretations in solving engineering problems of the machinery condition monitoring, diagnostics, and health monitoring. In particular, the term “condition monitoring” shall be understood as monitoring of state parameters without diagnostics.
It is shown that the vibroacoustic signal is a random process, and the vibroacoustic diagnostics requires analysis of its stochastic characteristics. For this reason, it is necessary to measure vibration acceleration, velocity and displacement, since the stochastic characteristics of these vibroacoustic oscillation parameters are statistically independent.
The studies performed brought us to the conclusion that the real-time health monitoring systems should provide real-time machinery diagnostics at such time intervals, during which the machinery state of health cannot change from normal to limit. In order to minimize the failure missing risk and ensure reliable diagnostics based-on the vibroacoustic signal parameters, one should measure the vibration acceleration, velocity and displacement with an accuracy of few percent over the frequency range of at least 3000 Hz.
The purpose of the paper is to present the basic terminology of diagnostics, monitoring and vibroacoustics and its application to the real engineering solutions.
The terminology is suggested by guidelines and regulations, reference, scientific and educational materials, including the researches carried out by the authors.
The analysis of the terminology used in Russia and abroad revealed the differing interpretations in solving engineering problems of the machinery condition monitoring, diagnostics, and health monitoring. In particular, the term “condition monitoring” shall be understood as monitoring of state parameters without diagnostics.
It is shown that the vibroacoustic signal is a random process, and the vibroacoustic diagnostics requires analysis of its stochastic characteristics. For this reason, it is necessary to measure vibration acceleration, velocity and displacement, since the stochastic characteristics of these vibroacoustic oscillation parameters are statistically independent.
The studies performed brought us to the conclusion that the real-time health monitoring systems should provide real-time machinery diagnostics at such time intervals, during which the machinery state of health cannot change from normal to limit. In order to minimize the failure missing risk and ensure reliable diagnostics based-on the vibroacoustic signal parameters, one should measure the vibration acceleration, velocity and displacement with an accuracy of few percent over the frequency range of at least 3000 Hz.
