Some issues related to the feedback control of a baffled plate

Abstract

This paper addresses a few issues related to the active structural acoustic control (ASAC) of a baffled plate. The first part proposes a feedback control strategy according to which a SISO control system is built by using a volume displacement sensor and a set of actuators driven with a single amplifier. The location of the actuators is then optimized to achieve an open‐loop transfer function with alternating poles and zeros, as for systems with co‐located actuators and sensors. This important feature allows the use of low‐order controllers. The second part of the paper discusses the volume displacement sensor; the spatial aliasing of a discrete array sensor is first demonstrated and a new electrode design is proposed, which makes it possible to tailor the effective piezoelectric properties of PVDF films. This electrode is used to design a volume displacement sensor. Copyright © 2002 John Wiley & Sons, Ltd.

Numerical Computation of the Sound Radiation From a Planar Baffled Vibrating Surface

“…Figure 5 shows the results for the radiation efficiency of the first six axisymmetric modes for a clamped plate predicted using Eqs. (11), (14), (36), and (37). Figure 6 presents the same results for a simply-supported plate.…”

“…Therefore, comparing with Eq. (14), Eq. (20) is identified as a quantity proportional to the sound radiation efficiency of the sound source.…”

“…However, this matrix has been mainly used for active structural acoustical control of low-frequency noise radiated by vibrating structures. 14 Associated to the radiation resistance matrix are the radiation modes. These modes are related with surface velocity distributions that produce orthogonal sound pressure radiation fields.…”

Novel electrode concept for spatial filtering with piezoelectric films: experimental validation

“…The distribution of the effective piezoelectric properties to achieve a volume velocity sensor has been computed according to the theory described in. 2,6,7 Like in the previous example, the electrode density has been taken proportional to the effective piezoelectric properties, without correction to account for tridimensional effects in the electric field distribution within the thickness of the piezo film. The test plate is mounted in an aluminium frame and the simply supported boundary conditions are materialized by a dual elastomer joint (on both sides) with a circular cross section.…”

“…Although the spatial filtering of plates and shells with two-dimensional PVDF films has been suggested, 5 it has never been implemented in practice, for lack of capability of continuously shaping the piezoelectric properties of the sensor material. A way to turn around this difficulty by a proper electrode design was proposed by the present authors, [6][7][8] and applied to a cantilever beam covered with a two-dimensional PVDF film (copolymer) 2 ; this test compared the classical modal filter of the beam theory with the corresponding profile obtained with the new porous electrode; it showed that (i) the two electrodes give the same result, but (ii) none of them constitutes a good modal filter when the piezoelectric film is isotropic (d 31 = d 32 ). This somewhat puzzling result has been confirmed with finite element calculations using shell elements.…”