IDENTIFICATION TECHNIQUES FOR OPERATIONAL MODAL ANALYSIS – AN OVERVIEW AND PRACTICAL EXPERIENCES

Operational Modal Analysis, also known as Output Only Modal Analysis, has for several years been used for extracting modal parameters of mechanical structures. In this paper, an overview of the Frequency Domain Decomposition (FDD) technique and the Stochastic Subspace Identification (SSI) technique is given. Use of the recently developed projection channel technique in combination with the SSI technique is described and discussed. Practical experiences in the use of these techniques are illustrated from measurement examples by comparing the results from the different techniques.