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Journal ArticleDOI

Vibration and damping analysis of cylindrical shells with constrained damping treatment - a comparison of three theories

01 Apr 1995-Journal of Vibration and Acoustics (American Society of Mechanical Engineers)-Vol. 117, Iss: 2, pp 213-219
TL;DR: In this paper, the importance of extensional effects in the core and its effect on the loss factor is brought out in the study of cylindrical shells with a constrained damping layer treatment.
Abstract: Cylindrical shells with a constrained damping layer treatment are studied using three theories The finite element method is made use of in the study The nondimensional frequencies and loss factors predicted by the three theories are compared and the theories are evaluated The importance of inclusion of the extensional effects in the core and its effect on the loss factor is brought out in this study
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Journal ArticleDOI
TL;DR: A review of the different approaches used for modeling multilayered composite shells is given in this article, where the effects of variation in the lamination and geometric parameters of simply supported composite cylinders on the accuracy of the static and vibrational responses predicted by eight different modeling approaches (based on two-dimensional shear deformation theories).
Abstract: A review is made of the different approaches used for modeling multilayered composite shells. Discussion focuses on different approaches for developing two-dimensional shear deformation theories; classification of two-dimensional theories based on introducing plausible displacement, strain and/or stress assumptions in the thickness direction; first-order shear deformation theories based on linear displacement assumptions in the thickness coordinate; and efficient computational strategies for anisotropic composite shells. Extensive numerical results are presented showing the effects of variation in the lamination and geometric parameters of simply supported composite cylinders on the accuracy of the static and vibrational responses predicted by eight different modeling approaches (based on two-dimensional shear deformation theories).

444 citations

Journal ArticleDOI
TL;DR: In this paper, a finite element displacement analysis of multilayer sandwich beams and plates, each with n stiff layers and n−1 weak cores, is presented, where each layer has individual orthotropic properties of its own and the bending rigidities of the stiff layers are taken into account while direct stresses in cores are neglected in the analysis.
Abstract: A finite element displacement analysis of multilayer sandwich beams and plates, each with n stiff layers and n−1 weak cores, is presented. Each layer of the sandwich structure may have individual orthotropic properties of its own and the bending rigidities of the stiff layers are taken into account while direct stresses in cores are neglected in the analysis. The condition of common shear angle for all cores, which has been used by several authors is not implied in the formulation. Several examples on bending problems have been solved using lower-order elements and the accuracy of the results has been shown to be excellent. Two higher-order elements have also been developed but have not been found to yield much better results. The free vibration problems of multilayer sandwich structures have also been solved, and good accuracy is demonstrated.

148 citations

Journal ArticleDOI
TL;DR: In this article, a theory for the prediction of damping and natural frequencies of laminated composite beams with multiple viscoelastic damping layers is described, and the design of composite beams for maximizing the damping capacity is also presented.
Abstract: This paper describes the formulation of a theory for the prediction of damping and natural frequencies of laminated composite beams with multiple viscoelastic damping layers. The damping layers are constrained (or sandwiched) by anisotropic laminates. The in-plane shear strains of the damping layers and the constraining layers are included in the model. Closed-form solutions for the resonance frequencies and modal loss factors of the composite beam system under simple supports are derived using the energy and Ritz method. A parametric study has been conducted to study the variation of dynamic stiffness and modal loss factor of the system with structural parameters (e.g., the ply orientations of laminas, thickness of the damping layers and the laminates), operating temperature, and damping material properties. The design of composite beams for maximizing the damping capacity is also presented in this paper which includes the determination of operating temperature range corresponding to given structural parameters and finding optimal structural parameters corresponding to given temperature range. Finally, some experimental results are compared with theory for the cases of single and double damping layer beam systems that show good agreement between predicted and measured natural frequencies.

112 citations

Journal ArticleDOI
TL;DR: In this article, the governing equations of motion for the nonaxisymmetric and axisymmetric variational of a general multilayered cylindrical shell having an arbitrary number of orthotropic material layers have been derived using variational principles.
Abstract: The governing equations of motion for the nonaxisymmetric and axisymmetric variational of a general multilayered cylindrical shell having an arbitrary number of orthotropic material layers have been derived using variational principles. The refined analysis considers bending, extension, and shear deformations in all layers of a multilayered cylindrical shell, including rotary and longitudinal translatory as well as transverse inertias. The solution for a radially simply supported shell has been obtained and the procedure for determining the damping effectiveness in terms of the system loss factor for all families of the modes of vibration in a multilayered shell with elastic and viscoelastic layers is reported. Numerical results are reported in Part II of the paper.

68 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of aspect ratio, damping layer thickness, and fiber volume ratio on static and dynamic characteristics of composite laminates are also investigated, in connection with a semianalytical method for predicting the modal damping in simply supported specialty composite plates.
Abstract: Integrated damping mechanics for composite plates with constrained interlaminar layers of polymer damping materials are developed. Discrete layer damping mechanics are presented for composite laminates with damping layers, in connection with a semianalytical method for predicting the modal damping in simply supported specialty composite plates. Correlations between predicted and measured response in graphite/epox y plates illustrate the accuracy of the method. Additional application cases for graphite/epoxy plates of various laminations demonstrate the potential for higher damping than geometrically equivalent aluminum plates. The effects of aspect ratio, damping layer thickness, and fiber volume ratio on static and dynamic characteristics of the composite plate are also investigated. AMPING is a significant dynamic parameter for vibration and sound control, dynamic stability, positioning accu- racy, fatigue endurance, and impact resistance. Many current structural applications (e.g., large space structures, engine blades, and high-speed machinery) require light weight and high dynamic performance. Therefore, candidate sources of passive damping should add minimal parasitic weight and be compatible with the structural configuration. Two potential damping sources satisfying the previous re- quirements are the constrained damping layer approach and the damping capacity of composites. Constrained damping layers in isotropic metallic structures have been widely applied and investigated.1 They provide high damping, but tend to increase the structural weight and offer limited means for damping tailoring. The inherent damping capacity of compos- ite materials also seems promising. Although the damping of composite structures is not very high, it is significantly higher than that for most common metallic structures. Moreover, composites are the materials of preference in many cases, since they readily provide high specific stiffness and strength. More importantly, research on the damping mechanics of composite laminates2'4 and structures5'6 has shown that composite damp- ing is anisotropic, highly tailorable, and depends on an array of micromechanic al, laminate, and structural parameters. It has been further demonstrated that optimal tailoring may significantly improve the damped dynamic performance of composite structures.7 It seems likely that the combination of both approaches (i.e., composite structures with interlaminar damping layers) will offer the advantages of high damping, damping tailoring, good mechanical properties, and low weight addition. In addi- tion, the interlaminar damping concept is highly compatible with the laminated configuration of composite structures and their fabrication techniques. In contrast to isotropic materials, the variations in anisotropy and elastic properties of each

68 citations