Response of plates with unconstrained layer damping treatment to random acoustic excitation, part I: Damping and frequency evaluations
TL;DR: In this article, a complete understanding of the various modes of vibration and the modal damping associated with each mode is required for theoretical evaluation of the response of a structure under random acoustic excitation.
About: This article is published in Journal of Sound and Vibration.The article was published on 1980-03-08. It has received 17 citations till now. The article focuses on the topics: Normal mode.
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TL;DR: In this article, a finite annular element based on individual layer theory is developed for the analysis of circular plates with a constrained viscoelastic damping layer treatment, and the influence of core-to-facing thickness ratio and shear modulus of the core on the frequencies and loss factors of a circular plate with isotropic facing is analyzed.
40 citations
TL;DR: In this article, a technique for the extraction of acoustic intermodal coupling information from numerically modeled, baffled planar structures was proposed, and the technique generated results in close agreement to a parallel analytical development.
Abstract: This technique permits the extraction of acoustic intermodal coupling information from numerically modeled, baffled planar structures. The technique generates results in close agreement to a parallel analytical development. Below the coincidence wave number ratio, the intermodal coupling effects cannot be neglected with respecty to the total radiated power.
33 citations
TL;DR: In this paper, the natural frequencies and loss factors in cylindrical shells with a constrained viscoelastic layer between two isotropic, elastic facings are studied using the finite element method.
32 citations
TL;DR: In this paper, the effects of partial application on the modal frequencies, loss factors and mode shapes are discussed, and specific recommendations are made for the near-optimum distribution of the damping material on the panel surface which is effective for many modes of panel response.
30 citations
TL;DR: In this paper, a new 1-3 viscoelastic composite material (VECM) layer is designed in order to achieve improved passive damping characteristics of the unconstrained (UCLD)/constrained) layer damping treatment of structural vibration.
Abstract: A new 1-3 viscoelastic composite material (VECM) layer is designed in order to achieve improved passive damping characteristics of the unconstrained (UCLD)/constrained (PCLD) layer damping treatment of structural vibration. The present 1-3 VECM layer is used instead of traditional monolithic viscoelastic material (VEM) layer within the UCLD/PCLD treatment. The corresponding change in damping is studied through the static as well as dynamic finite element (FE) analyses of a substrate beam integrated with the UCLD/PCLD treatment. The static analysis reveals augmentations of damping in the use of 1-3 VECM layer. The dynamic analysis quantifies improvement in the passive unconstrained/constrained layer damping through the present design.
21 citations
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TL;DR: In this article, a simple differential equation is derived to describe constrained-layer damping in nonsymmetric sandwich plates and beams composed of isotropic and homogeneous layers, and the natural boundary conditions related to this equation are determined.
Abstract: A simple differential equation is derived to describe constrained-layer damping in nonsymmetric sandwich plates and beams composed of isotropic and homogeneous layers. The natural boundary conditions related to this equation are determined and some typical numerical results obtained by this equation are given. The equation is valid within the linear theories of elasticity and viscoelasticity in the absence of any constraints on thicknesses, positions, symmetries, and densities of the layers.
215 citations
TL;DR: In this paper, the authors analyzed the energy dissipation due to thicknesswise motion of viscoelastic layers attached to plates in order to supplement previous analyses of damping due to shear, flexural, and inplane extensional motions.
Abstract: Energy dissipation due to thicknesswise motion of viscoelastic layers attached to plates is analyzed in order to supplement previous analyses of damping due to shear, flexural, and in‐plane extensional motions. It is shown that the thicknesswise motion may constitute an important damping mechanism for relatively soft and thick viscoelastic layers at frequencies corresponding to standing‐wave resonances in the damping layer. The general behavior of thickness‐compression damping layers is discussed on the basis of a relatively simple analysis, and reasonable agreement between theory and experimental results is demonstrated.
31 citations
TL;DR: In this paper, the authors used the principle of virtual work to derive the equations of motion in an invariant form for an arbitrary three-layered composite, where no restrictions were placed on the relative thicknesses, densities, elastic moduli, or symmetries of the layers.
Abstract: T use of composite materials in various aerospace and industrial applications has prompted a considerable amount of research on the static and dynamic response of multilayer plates. During the past decade, several authors' have formulated plate theories by a direct extension of Mindlin's theory for homogeneous plates. Sun and Whitney have shown that laminated plate theories which are based on Kirchhoff's hypothesis, or a simple extension of Mindlin's theory, yield grossly inaccurate natural-frequency predictions for twoand three-layer plates whose layers have widely differing shear rigidities. In a recent paper, the principle of virtual work was used to derive the equations of motion in an invariant form for an arbitrary three-layered plate. No restrictions were placed on the relative thicknesses, densities, elastic moduli, or symmetries of the layers. The formulation accounts for the shear deformation of each layer as well as the translational and rotational inertia of the composite. Continuity of displacements and stresses was imposed in accordance with a perfect interface bond assumption. In the current analysis, the previously derived equations will be used to analyze a transversely isotropic two-layer plate by deleting the terms associated with the third layer and neglecting the transverse contraction of the composite. The theory then becomes the two-dimensional analog of Theory II as presented by Sun and Whitney. If we assume that each layer is transversely isotropic, the equations of motion are written in vector notation and can be uncoupled to yield a sixth-order equation in the transverse displacement. By neglecting certain in-plane and rotatory inertia terms, we can obtain a somewhat simpler fourth-order equation, which is very similar to Mindlin's dynamic plate equation with modified stiffness, mass, and inertia coefficients. This equation reduces to Mindlin's formulation if either of the layers is assumed to vanish or the properties of both layers are identical. From virtual work, the natural boundary conditions
15 citations
TL;DR: In this paper, a series of measurements were carried out to examine the effectiveness of vibration damping layers on 2×1 m2 thin metal plates, which were covered with viscoelastic damping.
12 citations
TL;DR: Elastic metal thin plates transverse resonant free vibrations, analyzing viscoelastic coatings damping effects as discussed by the authors, were used to analyze the damping effect of thin plate thinning.
Abstract: Elastic metal thin plates transverse resonant free vibrations, analyzing viscoelastic coatings damping effects
10 citations