Sound Transmission Loss of Adaptive Sandwich Panels Treated With MR Fluid Core Layer

2016 ◽  
Author(s):  
Masoud Hemmatian ◽  
Ramin Sedaghati
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Transmission Loss ◽  
Sandwich Panels ◽  
Sound Transmission ◽  
Core Layer ◽  
Sound Transmission Loss ◽  
Mr Fluid ◽  
Low Frequencies ◽  
Fluid Core

This study aims to investigate the sound transmission loss (STL) capability of sandwich panels treated with Magnetorheological (MR) fluids at low frequencies. An experimental setup has been designed to investigate the effect of the intensity of the applied magnetic field on the natural frequencies and STL of a clamped circular plate. A multilayered uniform circular panel comprising two elastic face sheets and MR fluid core layer is fabricated. It is shown that as the applied magnetic field increases, the fundamental natural frequency of the MR sandwich panel increases. Moreover, the STL of the panel at the resonance frequency considerably increases under applied magnetic field. Furthermore, an analytical model for the STL of the finite multilayered panels with MR core layer is developed and compared with the experimental measurements. The MR core layer is treated as a viscoelastic material with complex shear modulus. It is shown that good agreement exists between the analytical and experimental results. Parametric study has also been conducted to investigate the effect of face sheets and core layers’ thickness.

Active damping of sound transmission through an electrorheological fluid-actuated sandwich cylindrical shell

2018 ◽  
Vol 22 (3) ◽  
pp. 833-865 ◽  
Author(s):  
Seyyed M Hasheminejad ◽  
Masoud Cheraghi ◽  
Ali Jamalpoor
Keyword(s):  
Cylindrical Shell ◽  
Sliding Mode Control ◽  
Transmission Loss ◽  
Sliding Mode ◽  
Sound Transmission ◽  
Core Layer ◽  
Electrorheological Fluid ◽  
Sound Transmission Loss ◽  
Mode Control ◽  
Fluid Core

An exact model is proposed for sound transmission through a sandwich cylindrical shell of infinite extent that includes a tunable electrorheological fluid core, and is obliquely insonified by a plane progressive acoustic wave. The basic formulation utilizes Hamilton’s variational principle, the classical and first order shear deformation shell theories, the Kelvin–Voigt viscoelastic damping model (for the electrorheological fluid-core layer), and the wave equations for internal/external acoustic domains coupled by the proper fluid/structure compatibility relations. The Fourier–Bessel series expansions are used to arrange the governing (coupled) system equations in state-space form. The classical Sliding Mode Control law is then applied to semi-actively reduce sound transmission through the composite cylinder by smart variation of stiffness and damping characteristics of the electrorheological fluid-core actuator layer according to the control command. Numerical results present both the uncontrolled and controlled sound transmission loss spectra of the sandwich cylindrical shell at three angles of incidence for three distinct sets of material input parameters that represent the electric-field dependency of the complex shear modulus of the electrorheological fluid-core layer. The superior soundproof performance of electrorheological fluid-based sliding mode control system in avoiding the highly detrimental sound transmission loss dips occurring throughout the critical resonance and coincidence regions is demonstrated. Likewise, remarkable enhancements in the sound insulation characteristics of the electrorheological fluid-actuated structure utilizing the first or second electrorheological fluid material model are achieved within the stiffness-controlled region, especially at lower frequencies in near-grazing incidence situation. A number of limiting cases are introduced and validity of the formulation is confirmed by comparison with the available data.

Prediction of Sound Transmission Loss for Finite Sandwich Panels Based on a Test Procedure on Beam Elements

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Zhongchang Qian ◽  
Daoqing Chang ◽  
Bilong Liu ◽  
Ke Liu
Keyword(s):  
Sandwich Panel ◽  
Transmission Loss ◽  
Test Procedure ◽  
Sandwich Panels ◽  
Sound Transmission ◽  
Expansion Method ◽  
Bending Stiffness ◽  
Sound Transmission Loss ◽  
Modal Expansion ◽  
Beam Elements

An approach on the prediction of sound transmission loss for a finite sandwich panel with honeycomb core is described in the paper. The sandwich panel is treated as orthotropic and the apparent bending stiffness in two principal directions is estimated by means of simple tests on beam elements cut from the sandwich panel. Utilizing orthotropic panel theory, together with the obtained bending stiffness in two directions, the sound transmission loss of simply-supported sandwich panel is predicted by the modal expansion method. Simulation results indicated that dimension, orthotropy, and loss factor may play important roles on sound transmission loss of sandwich panel. The predicted transmission loss is compared with measured data and the agreement is reasonable. This approach may provide an efficient tool to predict the sound transmission loss of finite sandwich panels.

Predicting the Sound Transmission Loss of Honeycomb Panels using the Wave Propagation Approach

2011 ◽  
Vol 97 (5) ◽  
pp. 869-876 ◽  
Author(s):  
Sathish Kumar ◽  
Leping Feng ◽  
Ulf Orrenius
Keyword(s):  
Wave Propagation ◽  
Transmission Loss ◽  
Plate Theory ◽  
Sandwich Panels ◽  
Sound Transmission ◽  
Structural Vibration ◽  
Sound Transmission Loss ◽  
Resonance Frequencies ◽  
Fluid Coupling ◽  
Vibration And Sound Radiation

The sound transmission properties of sandwich panels can be predicted with sufficient degree of accuracy by calculating the wave propagation properties of the structure. This method works well for sandwich panels with isotropic cores but applications to panels with anisotropic cores are hard to find. Honeycomb is an example of anisotropic material which when used as a core, results in a sandwich panel with anisotropic properties. In this paper, honeycomb panels are treated as being orthotropic and the wavenumbers are calculated for the two principle directions. These calculated wavenumbers are validated with the measured wavenumbers estimated from the resonance frequencies of freely hanging honeycomb beams. A combination of wave propagation and standard orthotropic plate theory is used to predict the sound transmission loss of honeycomb panels. These predictions are validated through sound transmission measurements. Passive damping treatment is a common way to reduce structural vibration and sound radiation, but they often have little effect on sound transmission. Visco-elastic damping with a constraining layer is applied to two honeycomb panels with standard and enhanced fluid coupling properties. This enhanced fluid coupling in one of the test panels is due to an extended coincidence range observed from the dispersion curves. The influence of damping treatments on the sound transmission loss of these panels is investigated. Results show that, after the damping treatment, the sound transmission loss of an acoustically bad panel and a normal panel are very similar.

Research of Sound Transmission Loss of Aircraft Sidewall with the Resonators

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.

Assessments of shear core effects on sound transmission loss through sandwich panels using a two-scale approach

2017 ◽  
Vol 182 ◽  
pp. 227-237 ◽  
Author(s):  
Z. Zergoune ◽  
M.N. Ichchou ◽  
O. Bareille ◽  
B. Harras ◽  
R. Benamar ◽  
...  
Keyword(s):  
Transmission Loss ◽  
Sandwich Panels ◽  
Sound Transmission ◽  
Sound Transmission Loss

Sound Transmission Loss of Adhesively Bonded Sandwich Panels with Pyramidal Truss Core: Theory and Experiment

2015 ◽  
Vol 07 (01) ◽  
pp. 1550013 ◽  
Author(s):  
C. Shen ◽  
Q. C. Zhang ◽  
S. Q. Chen ◽  
H. Y. Xia ◽  
F. Jin
Keyword(s):  
Adhesive Bonding ◽  
Transmission Loss ◽  
Sandwich Panels ◽  
Sound Transmission ◽  
Homogenization Theory ◽  
Sound Insulation ◽  
Sound Transmission Loss ◽  
Adhesively Bonded ◽  
Effective Elastic Constant ◽  
Standing Wave Tube

In this paper, an analytical model is developed to investigate sound transmission loss characteristic of adhesively bonded metal sandwich panels with pyramidal lattice truss cores based on 3D elasticity theory. Meanwhile, practical specimen is fabricated to conduct corresponding sound insulation experiment test via a standing wave tube method. The effective elastic constant of truss cores is derived using one homogenization theory on account of equivalent strain energy. It is found that satisfactory agreement is achieved between theoretical solutions and experiment results, and damping effect of adhesive bonding interface between facesheets and core has a great impact on transmission loss. Further parameter investigations demonstrate the significant effect of the elevation and azimuth angles of the pyramidal cores, which can be conveniently changed to tailor the acoustic performance of the sandwich panels in the whole frequency range.

Sign in / Sign up

Export Citation Format

Share Document