ESDU 98020:2011
$62.40
Estimation of Transmission Efficiencies of Coupled Plates
| Published By | Publication Date | Number of Pages |
| ESDU | 2011-02 | NA |
General
The three fundamental wave types that can propagate in plates
are bending, shear and longitudinal waves. A wave type that is
incident on a junction can be transmitted and reflected as all
three types as illustrated in Sketch 2.1. This wave propagation in
structures is sometimes referred to as structure-borne sound
(Derivation 3).
This Item permits estimation of the ratio of transmitted to
incident wave power, that is, the transmission efficiencies of an
arbitrary junction of between two and six coupled thin isotropic
plates. The plates can either be coupled directly as in Sketch 2.1,
or via a beam element as shown in Sketch 2.2.
There are two main applications of this Item. Firstly, it allows
the evaluation, of the attenuation expressed as the transmission
loss, Rijpr, of vibrational power
through different plate junctions, and the determination of the
percentage of the incident wave power that is being transmitted as
bending, shear and longitudinal wave power. Secondly, the Data Item
allows the calculation of diffuse field transmission efficiencies
in 1/3-octave bands, octave bands or at a user defined constant
bandwidth. These can be used to calculate coupling loss factors for
SEA (Statistical Energy Analysis) models.
Transmission efficiencies of coupled plates are functions of the
angle of incidence, ß. If the movement of the junction is not
restricted, as is assumed in this Item, then bending waves and at
least one of the other wave types (longitudinal or shear in the
plates or torsion or longitudinal in the beam element) will
normally be present, and then the transmission efficiencies will
also be functions of frequency.
The transmission efficiencies for coupled plates have also some
application for coupled curved plates and for coupled beams. Above
the ring frequency, a curved plate behaves with good accuracy as a
flat plate. Transmission efficiencies for flat plates can therefore
be used to describe a similar coupling between curved plates for
frequencies above their ring frequencies. For coupled beams, the
transmission efficiencies are identical to those of a similar plate
system at normal incidence (ß=0).