Vibro-acoustic response of a circular isotropic cylindrical shell under a thermal environment
01 Sep 2011-International Journal of Applied Mechanics (Imperial College Press)-Vol. 03, Iss: 03, pp 525-541
TL;DR: In this paper, the authors presented numerical simulation studies on the vibration and acoustic response-characteristics of an isotropic cylindrical shell under a thermal environment using commercial softwares ANSYS and SYSNOISE.
Abstract: This paper presents numerical simulation studies on the vibration and acoustic response-characteristics of an isotropic cylindrical shell under a thermal environment using commercial softwares ANSYS and SYSNOISE. First, the critical buckling temperature is obtained, followed by modal and harmonic response analyses considering pre-stress due to the thermal field in the cylindrical shell, with the critical buckling temperature as a parameter. The vibration response predicted is then used to compute the sound radiation. It is found that there is a significant change in the vibration mode shapes and ring frequency towards the lowest natural frequency with an increase in temperature. There is a sudden increase in overall sound power level near the critical buckling temperature and significant changes in mode shapes with temperature does not affect the overall sound power level.
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TL;DR: In this article, the acoustic radiation responses of doubly curved laminated composite shell panels subjected to harmonic excitation are investigated numerically in the framework of the higher-order shear deformation theory.
Abstract: In this article, the acoustic radiation responses of doubly curved laminated composite shell panels subjected to harmonic excitation are investigated numerically in the framework of the higher-order shear deformation theory. A general mathematical model for the vibrating curved panel has been developed and the cylindrical, spherical, elliptical and hyperboloid shell panel geometries resting on an infinite rigid baffle are considered for analysis. The desired response is computed using an in-house code developed in MATLAB. Firstly, the natural frequencies of the vibrating shell panel are obtained using the present model and validated with data available in the literature with experimental test results. A coupled finite element/boundary element formulation is then used to obtain the acoustic response of the structure. The mean square velocity, radiation efficiency and the sound power radiated are chosen as the acoustic response indicators. The effect of different support conditions, lamination schemes, aspect ratio and geometry of the vibrating doubly curved shell panel on the acoustic radiation behaviour is investigated and discussed in detail. It is observed that the support conditions and the lamination scheme greatly influence the acoustic radiation from the panels. On the other hand, the radiation pattern is quite similar for different geometries with a substantial distinction for flat plate.
20 citations
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TL;DR: In this article, a higher-order coupled finite-boundary element scheme is presented for the computation of the thermoacoustic responses of the layered panel structure under the harmonic excitation.
Abstract: A novel higher-order coupled finite-boundary element scheme is presented for the computation of the thermoacoustic responses of the layered panel structure under the harmonic excitation. The therma...
19 citations
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TL;DR: In this paper, an analytical study for vibration and acoustic radiation of a finite thin orthotropic composite cylindrical shell excited by a harmonic concentrated force in a hygroscopic environment is presented.
Abstract: An analytical study is presented for vibration and acoustic radiation of a finite thin orthotropic composite cylindrical shell excited by a harmonic concentrated force in a hygroscopic environment....
18 citations
Cites methods from "Vibro-acoustic response of a circul..."
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01 Sep 2018
TL;DR: In this article, the vibration-induced acoustic responses of laminated composite flat panels subjected to harmonic mechanical excitation under uniform temperature load are investigated numerically, and the results show that the flat panels exhibit similar acoustic responses to the vibration induced acoustic response of the same type of flat panels.
Abstract: In this article, the vibration-induced acoustic responses of laminated composite flat panels subjected to harmonic mechanical excitation under uniform temperature load are investigated numerically....
17 citations
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TL;DR: In this paper, the vibroacoustic responses of laminated composite curved panels subjected to harmonic point excitation in a combined temperature and moisture environment are investigated numerically using a novel higher-order finite-boundary element model.
Abstract: In this article, the vibroacoustic responses of laminated composite curved panels subjected to harmonic point excitation in a combined temperature and moisture environment are investigated numerically using a novel higher-order finite-boundary element model. The hygrothermal dependent composite material properties are incorporated macroscopically in the formulation. The governing equations are derived using the higher-order shear deformation shell theory coupled with finite and boundary element approach. First, the Hamilton's principle is employed to obtain the stiffness, mass tensors and modal values of the vibrating structure subjected to hygrothermal stresses. The acoustic radiation responses are then computed by solving the Helmholtz wave equation discretized on the structure boundary using boundary elements coupled with the structural finite elements. Compared to those reported in open literature, the results for natural frequencies, critical buckling temperature, critical buckling moisture and sound power level values computed using the present scheme are found to be more accurate. The sound power values are also acquired via a simulation model implemented using commercial tools ANSYS and LMS. Virtual Lab and compared with present numerical results. The scheme is further extended to solve numerous numerical examples highlighting the influence of hygrothermal loads, geometry, curvature ratio, modular ratio, support conditions and lamination scheme on the hygro-thermo-acoustic responses of laminated composite shell panels.
16 citations
References
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TL;DR: In this article, the authors presented numerical studies on the vibration and acoustic response characteristics of a fiber-reinforced composite plate in a thermal environment by considering the inherent material damping property of the composite material.
Abstract: This paper presents numerical studies on the vibration and acoustic response characteristics of a fiber-reinforced composite plate in a thermal environment by considering the inherent material damping property of the composite material. Initially the critical buckling temperature is obtained, followed by free and forced vibration analyses considering the pre-stress due to the imposed thermal environment. The vibration response predicted is then used to compute the sound radiation. The critical buckling temperature and vibration response are obtained using the finite element method based on the Classical Laminate Plate Theory (CLPT) while sound radiation characteristics are obtained using a coupled FEM/BEM technique. It is found that the vibration response of the structure reduces with an increase in uniform temperature rise for both Glass Epoxy and PEEK/IM7 materials, but the overall sound radiation of the plate reduces only marginally due to interaction between reduced stiffness and enhanced damping.
113 citations
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TL;DR: In this paper, the modal-averaged sound radiation efficiencies of acoustically thick circular cylindrical shells are calculated based on this method, and it is found that unlike acoustic-thick shells, the radiation efficiency depends on the acoustic behaviour of each individual vibration mode, and thus on the geometries and the boundary conditions.
Abstract: The acoustic radiation from circular cylindrical shells is of fundamental and applied interest primarily because cylindrical shells are widely used in industry, and because their acoustic behaviour is different from that of beams and plates due to curvature effects. In previous studies of the subject, cylindrical shells have been categorized into acoustically thin and acoustically thick shells in terms of the ratio between the ring frequency f r and the critical frequency f C , i.e., f r / f C f r / f C >1 for acoustically thick shells. For acoustically thin shells, it has been found by statistical methods that the radiation efficiency has a peak at the ring frequency. Above the ring frequency, the shells behave like flat plates. For acoustically thick shells, especially with finite length, however, the behavior is not so clear. From the analysis in the wavenumber domain, a formula for calculating the modal radiation efficiency of finite length circular cylindrical shells (immersed in light fluid) under mechanical excitation is obtained analytically. Based on this method, the modal-averaged sound radiation efficiencies of acoustically thick circular cylindrical shells are calculated. It is found that unlike acoustically thin shells, the radiation efficiencies of acoustically thick cylindrical shells very much depend on the acoustic behaviour of each individual vibration mode, and thus on the geometries and the boundary conditions. Results obtained by acoustic boundary element calculations and experiments verify these conclusions.
58 citations
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TL;DR: In this article, an analytical study of radiation by a finite, stiffened cylindrical shell is presented, where the driving force is applied on the stiffener or directly on the shell and can be radial, tangential or longitudinal.
Abstract: An analytical study of radiation by a finite, stiffened cylindrical shell is presented. The model of stiffener used allows one to treat hollow cross-section cases encountered in industry. The driving force is applied on the stiffener or directly on the shell and can be radial, tangential or longitudinal. Fluid and structure equations are solved with modal analysis and use of the in vacuo non-stiffened basis. This leads to the calculation of radiation impedances and generalized mass and stiffness terms of stiffeners. Theoretical results are presented in radiated power, radial quadratic velocity and radiation coefficient (in both air and water); they show the influence of stiffeners on the vibro-acoustic shell behaviour in both fluids. Parameters such as shell and stiffener structural damping, relative location of force and stiffeners, and force direction are investigated. This gives some guidelines for noise reduction.
52 citations
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TL;DR: In this article, the structural and acoustical properties of a cylindrical shell with an internal floor partition are analyzed using a variational approach based on the artificial spring technique and an integro-modal approach.
Abstract: Vibroacoustic analysis of a finite isotropic thin cylindrical shell with an internal floor partition is presented in the present paper A general formulation is developed based on a variational approach in which the structural coupling between sub-structures is simulated using the artificial spring technique, while the acoustic field is computed by an integro-modal approach For validation purposes, numerical results are compared with experimental data Numerical analysis is performed to show the structural and acoustical effects of the floor on the internal pressure field Further analysis is made to identify contributions of individual structural modes to sound radiation The present paper illustrates how the two previously established methods (artificial spring technique and the integro-modal approach) can be combined into a vibroacoustic model in the prediction of the structural acoustic response of complex shaped cavities surrounded by structural boundaries
35 citations
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TL;DR: In this paper, the thermal buckling behavior of laminated cross-ply oval cylindrical shells is analyzed using finite element approach based on higher-order theory that accounts for the transverse shear and transverse normal deformations, and incorporates realistic through thickness approximations of the in-plane displacements.
Abstract: Thermal buckling behavior of laminated cross-ply oval cylindrical shells is analyzed using finite element approach. The formulation is based on higher-order theory that accounts for the transverse shear and transverse normal deformations, and incorporates realistic through the thickness approximations of the in-plane displacements. The strain–displacement relations are accurately introduced in the formulation. The contributions of work done by initial membrane state of thermal stress due to the higher-order function arising from the assumed displacement models are also included. The governing equations are obtained using the principle of minimum potential energy. The combined influence of higher-order shear deformation, shell geometry, ovality, and lay-up on the critical temperature parameter of laminated oval cylindrical shells is examined.
30 citations