Transmissibility across simply supported thin plates. I. Rectangular and square plates with and without damping layers

Abstract

The transmissibility across thin, simply supported, rectangular and square aluminum plates has been determined experimentally and found to agree closely with theoretical prediction through the frequency range of measurement, which extended from 25 to 3025 Hz. Both the rectangular and the square plates considered were uniquely supported by spring-steel flanges, which were designed to provide, for the first time, true simple supports that simulated almost identically the idealized supports assumed as boundary conditions in theoretical analyses for more than a century. For example, the first 20 resonant frequencies of the rectangular plate with these novel supports differed, with only one exception, by less than 0.55% from their predicted values. One important result obtained for the damped plates considered--which comprised aluminum plates plus applied tiles of high-damping compound to yield composite plates having damping factors of essentially 0.3--was that the measured transmissibility across the plates could be duplicated closely by an expression for transmissibility developed for an internally damped homogeneous plate having damping factors equal to those of the composite plates.Subject Classification: 40.24, 40.60, 40.20.

Sound radiation from perforated plates

“…Thus the realisation of such a boundary condition in practice is not easy. However, several attempts have been made in previous measurements involving this type of boundary condition [90,91,92]. Similar to the method used in [91], a 460 × 362 mm frame was constructed to support the plate.…”

A Plane and Thin Panel with Representative Simply Supported Boundary Conditions for Laboratory Vibroacoustic Tests

“…The use of machined groovesp roposed by Barnard and Hambric [9] wasalso suggested years ago by Hoppmann and Greenspon [8], butwith V-shaped grooves. In most of these publications [6,7,8,9,12], the reported experimental validations were all satisfactory,with agood agreement between measured and calculated natural frequencies, mobility or mean quadratic velocity of the panel. Note that the problem of achieving accurate simply supported boundary conditions, apart the specificobjective of vibroacoustic testing, has been also investigated for compression testing of uniaxially loaded panels as an example [13].…”

“…To the best of the authors knowledge, the only papers that explicitly aim at realizing ap anel with simply supported boundary conditions for vibroacoustic testing, and report both experimental setup and test of such apanel were published by Ochs and Olson [6], Champoux et al [7], Hoppmann and Greenspon [8], and Barnard and Hambric [9]. Note that as imilar setup to the one of Ochs and Olson [6] is depicted in Hansen [10] (but no reference to as pecificp ublication nor to an experimental validation wasgiven), and nearly identical experime ntal implementations were reported by Pan et al [11] and Yo on and Nelson [12]. The use of machined groovesp roposed by Barnard and Hambric [9] wasalso suggested years ago by Hoppmann and Greenspon [8], butwith V-shaped grooves.…”

Preliminary Experiments on Noise Reduction in Cavities Using Active Impedance Changes

“…Translational displacements are blocked while rotations about the cavity edges supporting the plate are allowed. A method of practical realization inspired by Ochs and Snowdon [36] has been used: a 0)3 mm thick steel strip is glued in part under the plate along its perimeter, while the other part is clamped on the cavity edges, as shown in Figure 7. This technique allows one to achieve hinged boundary conditions in remarkable agreement with those expected from the theory.…”