Section: New Results

Change/damage detection and isolation in the frequency domain

Participants : Gilles Canales, Laurent Mevel.

See modules  3.3 , 3.4 , and 6.5 .

The first year of the PhD thesis of G. Canales has been focused on understanding and developing some detection tests in the frequency domain. Indeed, advances in engineering have led to the increase in monitoring capacities (number of sensors). This calls for developing new and more efficient approaches to the monitoring problem. One such approach was to try to work out a frequency domain damage detection test.

A new residual based on the polyreference Least Square Complex Frequency domain (LSCF) identification method has been proposed and described in the 2007 report. It has been presented at [34] .

In the second year of Gilles Canales thesis, different frequency domain damage detection residuals have been derived for the transmissibility frequency domain method. It has been presented at [14] and has been submitted to SYSID 09 [15] .

Consistency and asymptotical normality of that residual have been proved. We monitor some small changes in the transmissibility equation, where the transmissibility is the ratio between output and input in the frequency domain. Assuming a single force is applied to the system, this leads to an output only frequency domain method, a relaxing hypothesis with respect to last year [34] .

Other frequency domain methods under investigation include OMAX, Maximum likelihood and frequency domain decomposition methods. Residuals for such techniques have been evaluated. G. Canales is currently writing his thesis.