Acoustic properties of composite lightweight structures
Invited paper
University of Brescia
Tuesday 2 june, 2015, 09:40 - 10:00
0.1 London (90)
Abstract:
Lightweight structures are of great importance not only in vehicles but also
in many buildings. To meet a growing demand, a variety of different types of
sandwich panels has been developed during the last few decades. The term
“sandwich panel” here refers to a structure with a fairly thick lightweight
core with thin laminates bonded to each side of either a foam or honeycomb
core. This type of plate can combine low weight with high strength. However,
for certain types of composite plates, the acoustic properties can be very
poor. The absence of acoustic qualities can severely restrict the use of
lightweight elements. It is therefore essential to optimize through prediction
the acoustic properties of such structures. Some of the basic parameters of a
sandwich structure can be determined by means of some simple tests using a
beam element of the structure. Alternatively, the material parameters can be
determined from simple point mobility measurements on a plate element. The
apparent bending stiffness of a sandwich construction strongly depends on
frequency and also on boundary conditions. Once the material properties are
determined the sound transmission loss and sound radiation ratio can be
predicted using some simple algorithms. The model can also be used for
parameter studies of the influence on the sound transmission loss and
radiation ratios due to changes of dimensions of laminates, core etc.