Optimization of a Composite Double-Walled Cylindrical Shell Lined with Porous Materials for Higher Sound Transmission Loss by using a Genetic Algorithm

2014 ◽  
Vol 50 (1) ◽  
pp. 71-82 ◽  
Author(s):  
H. Ramezani ◽  
A. Saghafi
Keyword(s):  
Genetic Algorithm ◽  
Cylindrical Shell ◽  
Porous Materials ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Transmission Loss

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 Sound transmission loss of hierarchically porous composites produced by hydrogel templating and viscous trapping techniques

2017 ◽  
Vol 1 (12) ◽  
pp. 2627-2637 ◽  
Author(s):  
Benjamin R. Thompson ◽  
Brogan L. Taylor ◽  
Qin Qin ◽  
Simeon D. Stoyanov ◽  
Tommy S. Horozov ◽  
...  
Keyword(s):  
Porous Materials ◽  
Pore Size ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Transmission Loss ◽  
Hierarchically Porous ◽  
Hierarchically Porous Materials ◽  
Porous Composites ◽  
Insulating Properties

We produced hierarchically porous materials using hydrogel templating and viscous trapping techniques and studied how their sound insulating properties depend on the pore size and porosity.

Application of Neural Network and Genetic Algorithm to the Optimum Design of Perforated Tube Mufflers

2009 ◽  
Vol 25 (3) ◽  
pp. N7-N16 ◽  
Author(s):  
M.-C. Chiu ◽  
Y.-C. Chang
Keyword(s):  
Neural Network ◽  
Experimental Data ◽  
Genetic Algorithm ◽  
Mathematical Model ◽  
Optimum Design ◽  
Transmission Loss ◽  
Research Work ◽  
Sound Transmission ◽  
Optimum Process ◽  
Sound Transmission Loss

AbstractResearch on new techniques of perforated silencers has been well addressed. However, the research work on shape optimization for a volume-constrained silencer within a constrained machine room is rare. Therefore, the optimum design of mufflers becomes an essential issue. In this paper, to simplify the optimum process, a simplified mathematical model of the muffler is constructed with a neural network using a series of input design data (muffle dimensions) and output data (theoretical sound transmission loss) obtained by a theoretical mathematical model (TMM). To assess the optimal mufflers, the neural network model (NNM) is used as an objective function in conjunction with a genetic algorithm (GA). Moreover, the numerical cases of sound elimination with respect to pure tones (500, 1000, 2000Hz) are exemplified and discussed.Before the GA operation can be carried out, the accuracy of the TMM is checked by Crocker's experimental data. In addition, both the TMM and NNM are compared. It is found that the TMM and the experimental data are in agreement. Moreover, the TMM and NNM confirm.The results reveal that the maximum value of the sound transmission loss (STL) can be optimally obtained at the desired frequencies. Consequently, it is obvious that the optimum algorithm proposed in this study can provide an efficient way to develop optimal silencers.

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.

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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