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Journal ArticleDOI

Vibration and Acoustic Response of an Isotropic Plate in a Thermal Environment

01 Oct 2008-Journal of Vibration and Acoustics (American Society of Mechanical Engineers)-Vol. 130, Iss: 5, pp 051005
Abstract: This paper presents numerical simulation studies on the vibration and acoustic response characteristics of an isotropic rectangular plate in a thermal environment using commercial finite element softwares ANSYS and SYSNOISE. First the critical buckling temperature is obtained, followed by modal and harmonic analyses considering prestress due to the thermal field in the plate, with the critical buckling temperature as a parameter. The vibration response predicted is then used to compute the sound radiation. It is found that the displacement response of the structure increases with an increase in temperature for all boundary conditions. The overall sound radiation of the plate marginally increases with an increase in temperature for all boundary conditions when the temperature approaches the critical buckling temperature although there is a sharp increase in sound power levels.

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Topics: Sound power (59%), Vibration (54%), Isotropy (52%) ...read more
Citations
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Journal ArticleDOI
Qian Geng1, Yueming Li1Institutions (1)
Abstract: A study on vibration and acoustic radiation characters of an isotropic rectangular thin plate under thermal environments is presented in this paper. It is assumed that thermal loads caused by thermal environments just change the structure stress state. Thermal stresses induced by uniform temperature rise of the plate are determined with the thermo-elastic theory. Then the stress state is used in the following dynamic analysis as a pre-stressed factor. It is observed that thermal loads influence the natural frequencies evidently, especially the fundamental natural frequency. The order of mode shapes stays the same. Dynamic response peaks float to lower frequency range with the increment of structure temperature. Acoustic radiation efficiency of the plate subjected to thermal loads decreases in the mid-frequency band. For validation, numerical simulations are also carried out. It can be found that the combined approach of finite element method (FEM) and boundary element method (BEM) is more appropriate for radiation problems.

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51 citations


Journal ArticleDOI
Xiangyang Li1, Kaiping Yu1Institutions (1)
Abstract: The paper is focused on the vibration and acoustic responses of the sandwich panels constituted of orthotropic materials applied a concentrated harmonic force in a high temperature environment. The natural frequencies together with corresponding modes are obtained under the thermal stresses by applying the piecewise low order shear deformation theory. The critical temperature is derived to prevent the thermal load excess. And the sound pressure distribution is derived by applying the Rayleigh integral. The analytical solution is verified by the numerical simulations. It is observed that the natural frequencies of the sandwich panel decrease with the increment of the temperature. The interchanges of the mode shapes occur because of the material anisotropy. The peaks of vibration and acoustic responses float to the low frequency domain due to the decrement of the natural frequencies. The influences caused by the high temperature environment on the sandwich panels are deeply discussed.

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47 citations


Journal ArticleDOI
Qian Geng1, Huan Li1, Yueming Li1Institutions (1)
TL;DR: Experiments to investigate the vibration and acoustic response characteristics of a clamped rectangular aluminum plate in thermal environments indicated that the initial deflection has a great influence on the natural vibration of the heated plate.

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Abstract: Experiments were performed to investigate the vibration and acoustic response characteristics of a clamped rectangular aluminum plate in thermal environments. Modal tests were carried out to study the influence of thermal environment on natural vibration. With the increment of structural temperature, natural frequencies of the plate decrease obviously. Mode shape interchange was observed for the modes with frequencies very close to each other. The thermally induced softening effect has unequal influences on the plate along the two in-plane directions. Numerical methods were also employed to study the experimental phenomena. Calculated results indicated that the initial deflection has a great influence on the natural vibration of the heated plate. Even a slight curvature can reduce the thermally induced softening effect obviously. Dynamic response tests were carried out under acoustic and mechanical excitations, and the measured results indicate that the variation in damping determines the response amplitudes at resonant peaks in the test.

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44 citations


Journal ArticleDOI
P.V. Joshi1, N.K. Jain1, G.D. Ramtekkar1Institutions (1)
Abstract: An analytical model is proposed for free vibration and geometrically linear thermal buckling phenomenon of a thin rectangular isotropic plate containing a continuous line surface or internal crack located at the centre of the plate using classical plate theory. The crack terms are formulated using Line Spring Model. The in-plane forces are due to the uniform heating of the cracked plate. Applying the Galerkin׳s method, the equation is transformed into Duffing equation which shows the effect of uniform rise in temperature on natural frequencies. A classical relation for buckling temperature for a cracked plate is also determined.

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36 citations


Journal ArticleDOI
Abstract: This article presents numerical simulation studies on the vibration and acoustic response characteristics of a multilayered viscoelastic sandwich plate in a thermal environment. Initially the critical buckling temperature is obtained followed by free and forced vibration analyses considering the pre-stress due to the imposed thermal environment in the plate. The vibration response predicted is then used to compute the sound radiation. The critical buckling temperature and vibration response are obtained using finite element method while sound radiation characteristics are obtained using boundary element method. It is found that resonant amplitude of both the vibration and acoustic response decreases with increase in temperature. The influence of core thickness, number of layers, type of thermal field, and type of viscoelastic core material on vibration response sound radiation characteristics are studied in detail.

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35 citations


Cites background from "Vibration and Acoustic Response of ..."

  • ...[12,13] studied the effect of thermal loading on vibration and acoustic response of isotropic and composite plates....

    [...]

  • ...The resonant amplitude of vibration and acoustic response increases with temperature rise for an isotropic plate [12] while the resonant amplitudes are decreasing with increase in temperature rise for the viscoelastic sandwich plate....

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References
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Journal ArticleDOI
Abstract: The thermal postbuckling behavior of graphite/epoxy multi-layered rectangular plates of various boundary conditions is studied using the finite element method. Temperature dependent thermal and elastic properties of the material are used in the analysis. The nonlinear finite element equations are solved as a sequence of linear eigenvalue problems to trace the thermal postbuckling paths of 15-layered symmetric angle-ply plates. The presence of secondary instability with an unsymmetric deformation mode has been identified for symmetric laminates under uniform temperature rise. In the case of linearly varying temperature rise through the thickness of the plate, the nonlinear equilibrium equations are solved by the modified Newton–Raphson technique to get the temperature-displacement curves.

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77 citations


Journal ArticleDOI
Junhong Park1, Luc Mongeau1, Thomas Siegmund1Institutions (1)
Abstract: The control of the forced vibration response of structures through the optimal tuning of its supports is desirable in many applications. Tuning may enhance the dissipation of vibration energy within the supports, thereby reducing fatigue and structure-borne noise. Two different models were developed to calculate the optimal support stiffness that minimizes the velocity response of homogeneous plates. The first model, based on the wave propagation at the edge, yields a good first cut approximation of the optimal properties. The optimal viscous and viscoelastic support stiffness for minimal reflection at the edge was calculated. Maximum absorption of the incident waves occurs when the viscous support stiffness matches the characteristic mechanical impedances of the plate. The second model, based on the Rayleigh–Ritz method, yields more accurate estimates of the optimal support stiffness required to minimize the forced velocity response of the finite rectangular plate. The optimal support properties calculated from the two different methods were in good agreement. This suggested that the modal response of the plate is strongly influenced by the wave reflections at the edges. Finally, the effects of support properties on the sound radiated from the plate were investigated. The optimal support stiffness that minimizes the radiated sound power was found to be smaller than the value that minimizes the velocity response. The results show that both the velocity response and sound radiation are strongly influenced by dissipation of vibration energy at the edges, and demonstrate that support tuning can yield significant noise and vibration reduction.

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48 citations


Journal ArticleDOI
Abstract: A direct-BEM/Fem method was proposed to analyze the vibration and acoustic radiation characteristics of a submerged structure. Model parameters of the structure and the fluid-structure interaction due to surrounding water were analyzed by using FEM and direct BEM. Vibration velocity of the outer hull surface and underwater sound pressure were computed through modal superposition technique. The direct-BEM/FEM method was first validated by analyzing a submerged cylindrical shell, then was used to analyze the vibro-acoustic behavior of a submarine stern structure. The results have demonstrated the direct-BEM/FEM method is more effective than FEM in computing the underwater sound radiation of the stern structure.

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46 citations


Journal ArticleDOI
Pradeep Vangipuram1, N. Ganesan1Institutions (1)
Abstract: The free vibration and damping characteristics of plates consisting of composite stiff-layers and an isotropic viscoelastic core were studied under thermal loads using finite element method. The temperature dependence of viscoelastic core properties and effects of pre-stresses are taken into account. The inherent composite damping and damping due to viscoelastic layer are compared. Parametric study is conducted with fiber angle, ply lay-up, and core thickness as parameters. The results show some interesting phenomenon like shifting of modes with temperature.

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44 citations


Journal ArticleDOI
A.R. Krishna Reddy1, R. Palaninathan1Institutions (1)
Abstract: A general high precision triangular plate bending finite element has been extended to the buckling analysis of laminated skew plates. This procedure involves development of the transformation matrix between global and local degrees of freedom for nodes lying on the skew edges and suitable transformation of the element matrices. The accuracy of the present formulation has been verified against literature values. New results are obtained for antisymmetric angle-ply and cross-ply laminated skew plates. In this analysis, the critical buckling loads for different skew angles with various lamination parameters, such as number of layers, fibre orientation angle, different boundary (simply supported, clamped) and loading (uniaxial, biaxial) conditions, have been presented.

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37 citations