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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06 Jan 2020
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TL;DR: In this article, a semi-analytical finite element method was implemented to study the frequency and loss factor values of a mild steel sandwich shaft disc system with mild steel as the facing layers.
Abstract: This work aims at estimating and comparing the frequency and loss factor of a mild steel sandwich shaft disc system containing viscoelastic, electro-rheological fluid (ERF), and magneto-rheological fluid (MRF) core materials with mild steel as the facing layers. Because the structure is axisymmetric, a semi-analytical finite element method was implemented to study the frequency and loss factor values of the mild steel sandwich shaft disc system. The effects of an electric field for the ERF material and a magnetic field for the MRF material on the vibration behavior of the mild steel sandwich shaft disc system were studied. A quantitative study identified the combination of mild steel facing with a viscoelastic core shaft disc system that produced the highest frequency and loss factor values. In addition, the effect of an electric field and a magnetic field on ERF and MRF core improves the damping performance of the structure.
6 citations
Cites background from "Vibration and damping analysis of c..."
...…cylindrical shells with various boundary conditions has been carried out (Stephenson and Rouch, 1993), in addition the damping characteristics of three layered conical shells and cylindrical shells with a constrained layer studied (Ramesh and Ganesan, 1994, 1995; Sathish Kumar et al., 1996, 1997)....
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TL;DR: In this paper, the fatigue life behavior and internal surface conditions of inherently damped Additive Manufactured (AM) specimens subjected to vibration bending are investigated, and it is shown that fatigue failures initiate near the surface of maximum strain/stress at porous features consistent with stock (non-optimized) LPBF process parameters.
Abstract:
The fatigue life behavior and internal surface conditions of inherently damped Additive Manufactured (AM) specimens subjected to vibration bending are under investigation. This study supports research that demonstrated 95% vibration suppression due to damping capability of AM components with 1–3% internal volume of unfused powder. The damping demonstrations have been carried out using laser powder bed fusion (LPBF) specimens of various thicknesses, lengths, and unfused internal powder configurations. In addition, damping is shown to be achievable with both nickel-based alloys and stainless steel specimens. Despite the promise of this method, the viability of fatigue performance is unknown. The following effort aims to address this structural integrity issue; specifically, this study explores whether internal pocket roughness or erosion caused by powder particle motion induces a fatigue life debit. These concerns are addressed by comparing the fatigue behaviors of unfused powder pocket and fully-fused nickel based alloy 718 specimens. Microscopy results confirmed a long suspected powder interaction phenomena as well as appearances of erosion. Furthermore, fractography supports that fatigue failures initiate near the surface of maximum strain/stress at porous features consistent with stock (non-optimized) LPBF process parameters.
5 citations
TL;DR: In this paper, the effect of various constrained layers (viscoelastic layer (VEL), electro-rheological fluid (ERF), and magneto rheological fluids (MRF) over natural frequency and damping loss factor with two different fiber orientations (0 and 90) for a Graphite/Epoxy (GR/E) composite sandwich shaft disc system was investigated.
Abstract: The main aim of this paper is to investigate the effect of various constrained layers (viscoelastic layer (VEL), electro-rheological fluid (ERF), and magneto-rheological fluid (MRF)) over natural fre- quency and the damping loss factor with two different fiber orientations (0 and 90) for a Graphite/Epoxy (GR/E) composite sandwich shaft disc system. The finite element technique is used to investigate the natural frequency and loss factor for various combina- tions. Furthermore, the vibrational characteristics of the composite sandwich shaft disc system are compared with those of the base structure without constrained layers. The study shows that introducing various constrained layers reduces the magnitude of natural frequency by up to 80%. The results also show that GR/ E composite with 90 fiber orientation acquires the highest frequency reduction. Among the proposed layers, VEL has the highest damping loss factor.
5 citations
Cites methods from "Vibration and damping analysis of c..."
...were presented with the help of modal strain energy method by Ramkumar and Ganesan (2009) and Badie et al....
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TL;DR: In this paper, the effect of various constrained layers [electro rheological fluid (ERF), magneto rheologically fluid (MRF), and viscoelastic layer (VEL)] over natural frequency and damping loss factor with five different fiber orientations (0, 30, 45, 60 and 90°) for a boron/epoxy (B/E), carbon/encoxy (C/E) and kevlar/eboxy (K/E)) shaft disc system was investigated.
Abstract: This paper focuses on investigating the effect of various constrained layers [electro rheological fluid (ERF), magneto rheological fluid (MRF) and viscoelastic layer (VEL)] over natural frequency and damping loss factor with five different fiber orientations (0, 30, 45, 60 and 90°) for a boron/epoxy (B/E), carbon/epoxy (C/E) and kevlar/epoxy (K/E) shaft disc system. Finite element technique is employed to evaluate the natural frequency and damping loss factor for various combinations. Also the vibrational characteristics of composite sandwich shaft disc system are compared for better damping capabilities. From the study VEL core shows excellent frequency and loss factor performances and the 90° fiber oriented composites is dominant in vibration damping. Also, it is evident that the damping performance of ERF and MRF core depends on applied electric and magnetic field.
5 citations
References
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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
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
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
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
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