Index of content:
Volume 115, Issue 3, March 2004
- STRUCTURAL ACOUSTICS AND VIBRATION 
115(2004); http://dx.doi.org/10.1121/1.1635415View Description Hide Description
In this paper, power flow propagation in plates connected in an L-joint is investigated in both the low and high frequency ranges. An exact solution is derived to describe the flexural, in-plane longitudinal and in-plane shear wave motion in the plates. The coupled plates are simply supported along two parallel sides, and free at the other two ends. A point force is used to generate flexural wave motion only. The flexural wave coefficients are determined from the boundary conditions, continuity equations at the driving force locations, and continuity equations at the corner junction of the plates. Structural intensity expressions are used to examine the structural noise transmission in the low and high frequency ranges. The contributions from the individual wave types are also examined.
115(2004); http://dx.doi.org/10.1121/1.1649331View Description Hide Description
The behavior of coupled elastic systems is often analyzed in terms of the admittances or impedances of the component systems. In many applications, the admittances are approximated by a small number of simple oscillators; i.e., a low-order truncation of the normal-mode expansion. Such an approach is reasonable in the neighborhood of system resonances, but is much less convenient and accurate in the neighborhood of antiresonances. Pole-zero product expansions of the sort employed in circuit analysis offer a potential means of improving the accuracy of low-order approximations. The validity of such representations of the admittance matrix is explored here, and it is noted that in general the off-diagonal components cannot be written in this fashion. Nevertheless, it is shown below that the entire admittance matrix of beam and plate strip systems can always be represented in the pole-zero product form. Further, the representation is shown to be valid even when the beam or plate is coupled to an arbitrary conservative elastic structure.