Frequency-independent radiation modes of interior sound radiation: Experimental study and global active control

Abstract

Active control of structural sound radiation is a promising technique to overcome the poor passive acoustic isolation performance of lightweight structures in the low-frequency region. Active structural acoustic control commonly aims at the suppression of the far-field radiated sound power. This paper is concerned with the active control of sound radiation into acoustic enclosures. Experimental results of a coupled rectangular plate-fluid system under stochastic excitation are presented. The amplitudes of the frequency-independent interior radiation modes are determined in real-time using a set of structural vibration sensors, for the purpose of estimating their contribution to the acoustic potential energy in the enclosure. This approach is validated by acoustic measurements inside the cavity. Utilizing a feedback control approach, a broadband reduction of the global acoustic response inside the enclosure is achieved.

Active control of composite fuselage type structures with enclosed acoustic cavity

“…This section presents the radiation efficiencies of the considered model, which rely solely on the dimensions of the cavity as well as the material constants of the contained air. For the calculations in this paper, an acoustic density of ρ = 1.204 kg/m 3 The calculated radiation efficienciess l,m (ω) for the composite test-structure are shown in Fig. 2 depending on the modal indices (l, m) according to Eq.…”

“…ASAC approaches are often concerned with the control of sound radiation from infinitely baffled plates radiating noise into the far-field [1]. For the sound radiation into cavities, cuboid cavities in contact with vibrating plates are commonly addressed [2,3].…”

“…A formulation of the frequency-independent ARMs for circular cylindrical shells is given in [11] based on the uncoupled acoustic modes. The advantage of the frequency-independence originates from the reduced complexity for real-time implementations, which is demonstrated for the sound radiation into the farfield [12] and into cavities [3]. However, due to acoustic modes of the cylindrical cavity which contain no information, this formulation may lead to a non-intuitive implementation for the cylindrical shell.…”

Experimental study on resonant acoustic damping for cabin noise reduction

“…According to whether external energy is available or not, traditional noise-reducing schemes can be classified into active and passive ones [1]. Thanks to the rapid development of silicon chips in recent years, the active control technology has remarkable progresses [2][3][4]. However, due to consideration of reliability and compatibility, the passive control technology is still the main noise-reducing scheme adopted in the aviation industry.…”

“…One of the typical works is the heterogeneous (HG) blanket, which consists of porous materials with discrete embedded masses to act as a distributed mass-spring-damper system. The HG blanket can not only suppress structure-borne sound but also enhance sound absorption at low-frequency resonances [4]. Therefore, the HG blanket can be regarded as a perfect fusion of the porous material and the dynamic absorber.…”