Abstract
This study aims at establishing a new in-situ observation system for evaluating the performance of an oil bearing. The method includes the following steps: (1) To set an oil bearing in a self-designed testing machine. (2) To monitor and record acceleration at different points on the testing machine. (3) To use Fast Fourier Transformation (FFT) to transform the time-domain acceleration into frequency spectrum; and (4) to apply directly the univariate autoregressive moving average model (univariate ARMA model) to dynamically analyze the performance of the bearing. In this way, one can in-situ detect the performance of an oil bearing with a specific oil content. The possibility of applying the univariate ARMA model in this study has been verified experimentally. Once (1) the involved exciting forces on the body and frame of testing machine to generate the subsequent wide-band-frequency vibration, and (2) the characteristic root(s) of Inertance with high dispersion coefficient, were obtained, the high-frequency dynamic characteristic root(s) of Inertance of the oil bearing is (are) also determined. The application of FFT to cross-link analysis of the vibration spectra of exciting forces and Inertance at different points has led to identify the various kinds of exciting forces at a specific point, and to obtain a qualitative understanding of Inertance. The results of Inertance by FFT are in consistence with those by univariate model in this experiment. Although in this study the univariate ARMA model is applied in an off-line mode, the on-line mode application is also expected to be valid.