Numerical investigation of active porous composites with enhanced acoustic absorption

• Published in: Journal of sound and vibration 2011-10, Vol.330 (22), p.5292-5308
• Main Author: ZIELINSKI, Tomasz G
• Format: Article
• Language: English
• Subjects: Absorption; Acoustic absorption; Acoustics; Exact sciences and technology; Foams; Fundamental areas of phenomenology (including applications); Inclusions; Linear acoustics; Noise: its effects and control; Numerical analysis; Physics; Porosity; Solid mechanics; Sound; Structural acoustics and vibration; Structural and continuum mechanics; Vibration; Vibration, mechanical wave, dynamic stability (aeroelasticity, vibration control...)
• ISSN: 0022-460X; 1095-8568
• DOI: 10.1016/j.jsv.2011.05.029

The paper presents numerical analysis – involving an advanced multiphysics modeling – of the concept of active porous composite sound absorbers. Such absorbers should be made up of a layer or layers of poroelastic material (porous foams) with embedded elastic inclusions having active (piezoelectric) elements. The purpose of such active composite material is to significantly absorb the energy of acoustic waves in a wide frequency range, particularly, at lower frequencies. At the same time the total thickness of composite should be very moderate. The active parts of composites are used to adapt the absorbing properties of porous layers to different noise conditions by affecting the so-called solid-borne wave – originating mainly from the vibrations of elastic skeleton of porous medium – to counteract the fluid-borne wave – resulting mainly from the vibrations of air in the pores; both waves are strongly coupled, especially, at lower frequencies. In fact, since the traction between the air and the solid frame of porous medium is the main absorption mechanism, the elastic skeleton is actively vibrated in order to adapt and improve the dissipative interaction of the skeleton and air in the pores. Passive and active performance of such absorbers is analyzed to test the feasibility of this approach. ► Acoustic absorption of foams with passive and active inclusions is investigated. ► Multiphysics modeling involves the Biot's poroelasticity, piezoelectricity, etc. ► Passive inclusions enhance absorption at some frequencies, but may also decrease it. ► Active composites are always superior to passive, or foams without inclusions. ► Frame is actively vibrated to enhance dissipative interaction with air in the pores.