On low frequency sound transmission loss of double sidebranches: A comparison between theory and experiment

This paper studies low-frequency sound transmission loss (STL) of an infinite orthogonally rib-stiffened sandwich structure flexibly connected with periodic subwavelength arrays of finite shunted piezoelectric patches. A complete theoretical model is proposed by three steps. First, the panels and piezoelectric patches on both sides are equivalent to two homogeneous facesheets by effective medium method. Second, we take into account all inertia terms of the rib-stiffeners to establish the governing equations by space harmonic method, separating the amplitude coefficients of the equivalent facesheets through virtual work principle. Third, the expression of STL is reduced. Based on the two prerequisites of subwavelength assumption and convergence criterion, the accuracy and validity of the model are verified by finite element simulations, cited experiments, and theoretical values. In the end, parameters affecting the STL performance of the structure are studied. All of these results show that the sandwich structure can improve the low-frequency STL effectively and broaden the sound insulation bandwidth.

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Research of Sound Transmission Loss of Aircraft Sidewall with the Resonators

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.214.194 ◽

2012 ◽

Vol 214 ◽

pp. 194-199

Author(s):

Li Ming Shi

Keyword(s):

Transmission Loss ◽

Sound Transmission ◽

Side Wall ◽

General Aviation ◽

Sound Transmission Loss ◽

Low Frequencies ◽

Theory And Experiment ◽

General Aviation Aircraft

This paper suggesting a method that improving T.L. at low frequencies of general aviation aircraft side wall configuration by installing resonators between double panel.In this paper, through the theory and experiment results, explains the proposed view is correct.

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Sound transmission loss characteristics of sandwich aircraft panels: Influence of nature of core

Journal of Sandwich Structures & Materials ◽

10.1177/1099636216652580 ◽

2016 ◽

Vol 19 (1) ◽

pp. 26-48 ◽

Cited By ~ 21

Author(s):

MP Arunkumar ◽

Jeyaraj Pitchaimani ◽

KV Gangadharan ◽

MC Lenin Babu

Keyword(s):

Sandwich Panel ◽

Transmission Loss ◽

Sheet Material ◽

Low Frequency ◽

Sandwich Panels ◽

Sound Transmission ◽

Sound Transmission Loss ◽

Honeycomb Core ◽

Transmission Characteristics ◽

The Impact

Sandwich panel which has a design involving acoustic comfort is always denser and larger in size than the design involving mechanical strength. The respective short come can be solved by exploring the impact of core geometry on sound transmission characteristics of sandwich panels. In this aspect, the present work focuses on the study of influence of core geometry on sound transmission characteristics of sandwich panels which are commonly used as aircraft structures. Numerical investigation has been carried out based on a 2D model with equivalent elastic properties. The present study has found that, for a honeycomb core sandwich panel in due consideration to space constraint, better sound transmission characteristics can be achieved with lower core height. It is observed that, for a honeycomb core sandwich panel, one can select cell size as the parameter to reduce the weight with out affecting the sound transmission loss. Triangular core sandwich panel can be used for low frequency application due to its increased transmission loss. In foam core sandwich panel, it is noticed that the effect of face sheet material on sound transmission loss is significant and this can be controlled by varying the density of foam.

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Normal Incidence of Sound Transmission Loss of a Double-Leaf Partition Inserted with a Microperforated Panel

Advances in Acoustics and Vibration ◽

10.1155/2013/216493 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

A. Putra ◽

A. Y. Ismail ◽

R. Ramlan ◽

Md. R. Ayob ◽

M. S. Py

Keyword(s):

Mathematical Model ◽

Transmission Loss ◽

Low Frequency ◽

Sound Transmission ◽

Normal Incidence ◽

Sound Transmission Loss ◽

Engineering Structures ◽

Air Mass ◽

Noise Barrier ◽

The Mathematical Model

A double-leaf partition in engineering structures has been widely applied for its advantages, that is, in terms of its mechanical strength as well as its lightweight property. In noise control, the double-leaf also serves as an effective noise barrier. Unfortunately at low frequency, the sound transmission loss reduces significantly due to the coupling between the panels and the air between them. This paper studies the effect of a microperforated panel (MPP) inserted inside a double-leaf partition on the sound transmission loss performance of the system. The MPP insertion is proposed to provide a hygienic double-leaf noise insulator replacing the classical abrasive porous materials between the panels. It is found that the transmission loss improves at the troublesome mass-air-mass resonant frequency if the MPP is located closer to the solid panel. The mathematical model is derived for normal incidence of acoustic loading.

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