The Sequel on the Identification of Modal Parameters from Transmissibility Measurements

In the first International Operational Modal Analysis Conference it was shown for the first time how transmissibility measurements can be used to identify modal parameters. The main advantage of this new technique is that it is no longer necessary to make the assumption that the inputs to the structure are white noise. The unknown operational forces can be arbitrary (colored noise, swept sine, impact, ...) as long as they are persistently exciting in the frequency band of interest. This paper will demonstrate this advantage through some experimental tests, were classic OMA procedures are, strictly speaking, not applicable. This is for example the case in many mechanical structures, where the loading forces are often more complex and harmonic components can be present in the responses. Especially if the harmonic frequencies are close to eigenfrequencies current techniques may encounter difficulties to correctly identify the modal parameters.