Identification Techniques in Rotordynamics

Abstract

In order to find out the condition of a rotating machine during operation usually vibrations (output signals) are measured at specified machine locations. Indications can be determined from these signals, which allow a diagnosis of possible failures (fault parameters) based on the support of expert knowledge and/or good rotordynamic models. However, the success of failure diagnostic would probably be much better, if in addition to the output signals more information would be available about rotor excitation forces. This leads to the idea of using Identification Techniques with measured input and output signals. Frequency response functions can than be calculated and an extraction of physical and/or modal parameters, expressing the actual system condition, is possible. This contribution describes the basic relations of Identification Techniques in rotordynamics, including rotordynamic models, measurement and excitation methods and parameter estimation procedures. Some applications of parameter identification are presented together with the corresponding test procedures and test apparatus.