MULTI-DIMENSIONAL CHARACTERIZATION OF VIBRATION ISOLATORS OVER A WIDE RANGE OF FREQUENCIES

This article presents a new experimental identification method for extracting frequency-dependent multi-dimensional dynamic stiffnesses of an isolator. The scope is limited to linear time-invariant system and analysis is performed only in the frequency domain. The proposed characterization method uses two inertial elements and an isolator, and a refined multi-dimensional mobility synthesis formulation is developed for estimating the properties of this system. For example, dynamic stiffnesses of an isolator are decomposed given the measured mobilities of the overall system and rigid body system theory. Approximate identification schemes for transfer dynamic stiffnesses, as proposed by prior researchers, are analytically examined for axial motions. The aforementioned approximate scheme is then extended to the identification of flexural stiffnesses. Both symmetric and asymmetric isolators are analyzed, based on a simulation example that models the isolator using a Euler beam and wave equation formulations for flexural and longitudinal motions respectively. Finally, the proposed identification method is applied to three rubber isolators up to 2 kHz, and transfer stiffness estimations are successfully compared with data measured on a commercial test machine for axial motions up to 1 kHz. Our method is very promising though its utility could be limited because of the zero preload assumption.