smart technologies for safety engineering

Smart Technologies in Vibroacoustics 313
significantly attenuated by adding a well-chosen layer of poroelastic material (apart from the
chosen one, two other foams and different thicknesses were tried). Though desirable damping
properties of the poroelastic layer are revealed owing to this simple one-dimensional analysis, it
cannot be stated how they affect the resonances relevant for the plate. To check this, a complete
three-dimensional FE model must be analysed.
8.10.4 Analysis of Passive Behavior of the Panel
Figure 8.13 presents the frequency analysis for the plate linked with the poroelastic layer
coupled to the acoustic medium. This time the piezoelectric patches are present but they are
passive (the only effect is some locally added mass and stiffness). As a matter of fact, an
analysis of the panel without patches was also carried out, but those results are not given here
because they are similar and the conclusions are identical to the ones presented below.
(a) ED FEM (b) 3D FEM (1/8 slice)
Figure 8.13 Frequency analyses: (a) the same curve as in Figure 8.9(d); (b) the results of the FE analysis
of the complete assembly of the panel, i.e. the simply-supported plate (with passive piezo-patches) merged
with the poroelastic layer connected to the acoustic medium (the limited 1/8-slice model was used)