Vibroacoustic characteristics and sound attenuation analyses of a duct–membrane system coupled with strip masses

Abstract

In this paper, the vibroacoustic characteristics and noise reduction behavior of a duct–membrane system with attached strip masses are investigated analytically. Fully coupled structural–acoustic interactions between membrane–mass dynamics and duct sound propagation are constructed using the energy formulation and Rayleigh–Ritz procedure. Results from the current model are compared to those calculated by finite element analysis to verify the accuracy and effectiveness of the proposed model. Effective dynamic density and average vibrational velocity of the membrane are explicitly demonstrated at the peak/valley frequencies of transmission loss. The transmission loss peak frequency for such a model can be tuned by the variation of mass position and its weight, in which the first peak is mainly dependent on the mass properties, while the second one is more sensitive to the mass position. An extension to noise reduction analysis of a three-dimensional duct–membrane coupling system is also conducted. Significant enhancement of duct silencing performance has been obtained for the first time by making use of strip mass attachment.

Low frequency noise control in duct based on locally resonant membrane with attached resonators

“…At this moment, the resonator contributes nothing to whole vibroacoustic system and can be removed completely. For the first and third peak frequencies, introduction of resonator has improved the equivalent bending stiffness of membrane, then the corresponding TL peak frequency become bigger according to the known relationship between frequency and stiffness as shown in Figure 2(b).

Figure 2.(a) Transmission loss for present model with an attached resonator; present results (circle), FEM (solid curve), without resonator (Liu and Du, 2019c) (dotted line). (b) Membrane velocity distributions at various peak frequencies.

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“…They (Liu and Du, 2019b) investigated sound wave propagation and attenuation in a duct with periodic membranes embedded on duct walls, which exhibit acoustic bandgaps via resonance and Bragg reflection. Furthermore, they (Liu and Du, 2019a, 2019c) replaced the membranes with strip mass-attached membrane array and found that the location and width of the Bragg and the resonant-gaps can be effectively and expediently adjusted by changing the mass position.…”

A low-frequency multiple-band sound insulator without blocking ventilation along a pipe

“…Meanwhile, membrane-type structures were also developed to simultaneously realize sound attenuation and air ventilation. A membrane with attached strips was used to replace a part of a pipe wall, which produces sound insulation at the resonant frequencies of distinct modes 32 . On the basis of the interaction of resonating field of four decorated membranes with the continuous sound field passing through a large orifice, a low-frequency and narrow-band acoustic filter was created 33 .…”

Controlling protein interactions in blood for effective liver immunosuppressive therapy by silica nanocapsules

“…14 There are two main strategies for the controlled delivery of DXM. In the first approach, DXM molecules were conjugated to hydrophilic polymers [15][16][17][18][19][20][21][22] and nanoparticles 23,24 via reactions with ketone [16][17][18][19][20]22,25,26 or hydroxyl 20,21,23,27 groups of DXM. The formed hydrazone or ester linkages allowed a specific release of DXM in response to acidic local environment in inflammatory tissues.…”