Using antiresonances to update finite element dynamic models

In this paper, an updating technique including antiresonances in the definition of the output residual is considered. Antiresonances are not a global system property, but are typical of each FRF, thus allowing to enlarge the residual vector with data identified from additional FRFs. However, antiresonance information is not independent of mode shape information, but it is rather an alternative, which is preferable for several reasons. In the implementation of the technique, matching problems arise whenever antiresonances identified from transfer FRFs are used: unlike in point FRFs, the distribution of antiresonances may be significantly altered by small changes in the structural model. Such problems may be circumvented by restricting the experimental database to point FRFs: in this case, very good results are obtained, but it is required to plan experimental testing differently from usual modal testing. To deal with transfer FRFs, matching between test and analysis FRFs at antiresonances can be sought through the FRAC (Frequency Response Assurance Criterion).