This work presents a method for characterizing elastic structures when spatially varying properties over the input and output contact regions are considered. Most analytical or experimental approaches, such as the four-pole parameter method, are limited by the inherent use of lumped quantities to represent critical parameters. When the excitation frequency increases, however, the structural wavelength becomes comparable to the dimensions of the contact region. As a result, the point-quantity assumption is no longer valid. To address this limitation, the work described here reformulates the traditional four-pole method in terms of quantities defined over planes. Consequently, spatial variations across the region connecting the structures can be considered. After the method is derived, it is applied to a simplified engine mount model in which two elastic beams are coupled through a set of elastic and inertial elements. Just like for the four-pole method, the formulation approach uses building blocks for simple structures that can be assembled to represent more complex structures. Some of the potential applications for this method are also discussed. By using this method, a meaningful characterization of the dynamic behavior can be obtained for structures when the frequency increases beyond that for which the point quantity approaches become invalid.
Biobjective Optimization of Vibration Performance of Steel-Spring Floating Slab Tracks by Four-Pole Parameter Method Coupled with Ant Colony Optimization