Design and valdation of advanced system identification techniques in the field of operational modal analysis

Present modal model identification methods and procedures are limited to forced excitation laboratory tests. The interest in in-operation modal analysis stems from the fact that in many cases (small excitation of offshore platforms, traffic/wind excitation of civil constructions) forced excitation test are very difficult, if not impossible, to conduct, at least with standard testing equipment. Furthermore, the availability of in-operation established models opens the way for in situ model-based diagnosis and damage detection. Hence, a considerable interest exists for techniques able to extract valid models directly from operating data. - The disgn of a global and robust strategy for the identification of the modal parameters from operational "outpit-only" measurements, based on a multivariable frequency-domain Maximum Likelihood approach. - The evaluation of the procedure on pratical measurement problems in the field of operational modal analysis: 1) the in-situ charaterisation of composit materials from non-contact LDV operational measurements (for damage detection purposes). 2) the operational modelling of e.g. agricultural spraying machines (for control purposes).