| The main objective of this research is the development of automatic modal analysis technique which can be applied on a machine in operation with only the output vibratory responses. This thesis thus presents a research on structural and machinery modal analysis in operation by using an autoregressive model. It is seen that such applications can be non stationary with time-varying physical properties; a new method for the modal surveillance in the time is developed. To reach the objectives, some original aspects have been developed such as the determination of a minimum required model order, the updating of the model with respect to the model order and to the time, the classification and determination of physical modes in a frequency range, the calculation of the uncertainties of the modal parameters.;Keywords: Non-stationary vibrations, Operational modal analysis, Multivariable autoregressive, QR factorization updating. |
