5. Modal identification

Modal identification methods were the subject of intensive research in the 1970s-1990s, and the abundant literature includes a huge number of methods and variants. We propose here a few criteria for classifying them according to their characteristics.

• The first distinction relates to the nature of the data – temporal or frequency – used as a starting point for the method. Today, most experimental modal identification software uses frequency data, while operational modal analysis tools (without measurement of applied forces) use time data.

• A second classification can be made according to whether the approaches are local or global in the frequency sense: a local approach deals with an isolated mode or a small group of coupled modes, and is therefore used iteratively; a global approach aims to simultaneously...