Analysis of sound transmission loss through thick-walled cylindrical shell using three-dimensional elasticity theory

2016 ◽  
Vol 106 ◽  
pp. 286-296 ◽  
Author(s):  
K. Daneshjou ◽  
R. Talebitooti ◽  
A. Tarkashvand
Keyword(s):  
Cylindrical Shell ◽  
Elasticity Theory ◽  
Transmission Loss ◽  
Three Dimensional ◽  
Sound Transmission ◽  
Sound Transmission Loss ◽  
Three Dimensional Elasticity

Functionally graded viscoelastic core characteristics on vibroacoustic behavior of double-walled cylindrical shells in a subsonic external flow

2022 ◽  
pp. 107754632110467
Author(s):  
Shohreh Reaei ◽  
Roohollah Talebitooti
Keyword(s):  
Cylindrical Shell ◽  
Transmission Loss ◽  
Excitation Frequency ◽  
Shear Deformation Theory ◽  
Sound Transmission ◽  
Functionally Graded ◽  
Loss Coefficient ◽  
Sound Transmission Loss ◽  
Polymeric Foam ◽  
The Core

The present study is concerned with an analytical solution for calculating sound transmission loss through an infinite double-walled circular cylindrical shell with two isotropic skins and a polymeric foam core. Accordingly, the two-walled cylindrical shell is stimulated applying an acoustic oblique plane wave. The equations of motion are derived according to Hamilton’s principle using the first-order shear deformation theory for every three layers of the construction. Additionally, by the aid of employing the Zener mathematical model for the core of polymeric foam, mechanical properties are determined. To authenticate the results of this study, the damping of the core layer goes to zero. Therefore, the numerical results in this special case are compared with those of isotropic shells. The results prove that the presented model has high accuracy. It is also designated that decreasing the power-law exponent of the core leads to improving the sound transmission loss through the thickness of the construction. Besides, in addition to probe some configurations versus alterations of frequencies and dimensions, the convergence algorithm is provided. Consequently, it is realized that by increasing the excitation frequency, the minimum number of modes to find the convergence conditions is enhanced. The results also contain a comparison between the sound transmission loss coefficient for four different models of a core of a sandwiched cylindrical shell. It is comprehended that the presented model has a transmission loss coefficient more than the other types of the core at high frequencies.

scholarly journals Optimization of Sound Transmission Loss through a Thin Functionally Graded Material Cylindrical Shell

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Ali Nouri ◽  
Sohrab Astaraki
Keyword(s):  
Cylindrical Shell ◽  
Functionally Graded Material ◽  
Transmission Loss ◽  
Minimum Weight ◽  
Sound Transmission ◽  
Functionally Graded ◽  
Sound Transmission Loss ◽  
Softening Effect ◽  
Important Concern ◽  
Graded Material

The maximizing of sound transmission loss (TL) across a functionally graded material (FGM) cylindrical shell has been conducted using a genetic algorithm (GA). To prevent the softening effect from occurring due to optimization, the objective function is modified based on the first resonant frequency. Optimization is performed over the frequency range 1000–4000 Hz, where the ear is the most sensitive. The weighting constants are chosen here to correspond to an A-weighting scale. Since the weight of the shell structure is an important concern in most applications, the weight of the optimized structure is constrained. Several traditional materials are used and the result shows that optimized shells with aluminum-nickel and aluminum-steel FGM are the most effective at maximizing TL at both stiffness and mass control region, while they have minimum weight.

Study on sound transmission loss modeling through simplified sealing specimens and an automotive door sealing system

2021 ◽  
Vol 69 (4) ◽  
pp. 301-330
Author(s):  
Guoming Deng ◽  
Jianwang Shao ◽  
Songlin Zheng ◽  
Xian Wu
Keyword(s):  
High Speed ◽  
Transmission Loss ◽  
Three Dimensional ◽  
Sound Transmission ◽  
Experimental Result ◽  
Sound Insulation ◽  
Sound Transmission Loss ◽  
Shell Elements ◽  
Design And Optimization ◽  
Hyper Elastic

An imperfect sealing system would be the main path of the noise propagating into the interior compartment of a high-speed vehicle. The study on the sound insulation modeling of automotive door sealing systems, which involve complicated threedimensional sealing structures and gap cavities, has attracted more and more attention. This study employs hybrid finite element–statistical energy analysis (FE-SEA) models to predict the sound transmission loss of three simplified sealing specimens and an actual automotive door sealing system. For the actual sealing system under compression, a three-dimensional FEmodel is built to simulate the nonlinear compression, which can acquire the compressed geometries and pre-stress modal results of the seals for further prediction of the sound transmission loss. The hybrid FE-SEA method is firstly verified by the experimental result of a double plate vibro-acoustic system and another numerical method. Several factors concerning the modeling, including the boundary conditions, the equivalent elastic modulus for the hyper-elastic rubber, the specimen length, and the structural grid size, are considered to study their impacts on the sound transmission loss. The effects of using shell elements and using solid elements to model the sealing rubber layers are also compared. The results of this study can provide guides regarding the trade-off between the modeling efficiency and accuracy, so that it has significance for engineering modeling, as well as the design and optimization of automotive door sealing systems.

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.

Control of sound transmission into a hybrid double-wall sandwich cylindrical shell

2021 ◽  
pp. 107754632098213
Author(s):  
Seyyed M Hasheminejad ◽  
Ali Jamalpoor
Keyword(s):  
Cylindrical Shell ◽  
Shell Structure ◽  
Transmission Loss ◽  
Sliding Mode ◽  
Circular Cylindrical Shell ◽  
Sound Transmission ◽  
Sound Field ◽  
Air Gap ◽  
Sound Transmission Loss ◽  
Double Wall

A 3D analytical model is formulated for diffuse sound field transmission control through a smart hybrid double concentric sandwich circular cylindrical shell structure in presence of external and internal air gap mean flows. The multi-input multi-output sliding mode control is applied to enhance the sound transmission loss characteristics via direct control action of a uniform force piezoelectric actuator layer along with semi-active variation of the stiffness/damping characteristics of the electrorheological fluid core layer incorporated in a non-collocated configuration within the external or internal shell structure. Extensive numerical simulations examine the uncontrolled/controlled diffuse field sound transmission loss spectrums in a broad frequency range for single-wall and hybrid double-wall sandwich shells at selected external and air gap Mach numbers. The proposed smart hybrid active/semi-active double-wall configuration is demonstrated to provide satisfactory overall acoustic insulation control performance with much lower operative energy requirements. Limiting cases are considered, and validity of the formulation is verified against the available data.

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