Optimal Damping in Circular Cylindrical Sandwich Shells With a Three-Layered Viscoelastic Composite Core

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Ambesh Kumar ◽  
Satyajit Panda
Keyword(s):  
Composite Layer ◽  
Middle Surface ◽  
Layered Composite ◽  
Fe Model ◽  
Sandwich Shell ◽  
Cylindrical Sandwich Shell ◽  
Viscoelastic Composite ◽  
Damping Characteristics ◽  
Viscoelastic Core ◽  
Viscoelastic Layers

In this work, the damping characteristics of circular cylindrical sandwich shell with a three-layered viscoelastic composite core are investigated. The new composite core is composed of the identical inclusions of graphite-strips which are axially embedded within a cylindrical viscoelastic core at its middle surface. The physical configuration of the composite core is attributed in the form of a cylindrical laminate of two identical monolithic viscoelastic layers over the inner and outer cylindrical surfaces of middle viscoelastic composite layer so that it is a three-layered viscoelastic composite core. A finite element (FE) model of the overall shell is developed based on the layerwise deformation theory and Sander's shell theory. Using this FE model, the damping characteristics of the shell are studied within an operating frequency range after configuring the size and circumferential distribution of graphite-strips in optimal manner. The numerical results reveal significantly improved damping in the sandwich shell for the use of present three-layered composite core instead of traditional single-layered viscoelastic core. It is also found that the three-layered core provides the advantage in achieving damping at different natural modes as per their assigned relative importance while it is impossible in the use of single-layered viscoelastic core.

scholarly journals Finite Element Modelling of Frequency-Dependent Dynamic Behaviour of Viscoelastic Composite Structures

2004 ◽  
Vol 13 (1) ◽  
pp. 096369350401300 ◽  
Author(s):  
Evgeny Barkanov ◽  
Andris Chate
Keyword(s):  
Finite Element ◽  
Composite Structures ◽  
Laminated Composite ◽  
Element Analysis ◽  
Viscoelastic Composite ◽  
Fitting Procedure ◽  
Damping Characteristics ◽  
Storage And Loss Moduli ◽  
Free Vibration Frequency ◽  
Viscoelastic Layers

Finite element analysis of sandwich and laminated composite structures with viscoelastic layers is performed. The present implementation gives the possibility to preserve the frequency dependence for the storage and loss moduli of viscoelastic materials exactly. Moreover, the storage and loss moduli in this case are defined directly in the frequency domain by an experimental technique for each material and can be used after curve fitting procedure in the numerical analysis. Damping characteristics of viscoelastic composite structures are evaluated by the energy method, the method of complex eigenvalues, from the resonant peaks of the frequency response function and using the steady state vibrations. Numerical examples are given to demonstrate the validity and application of the approaches developed for the free vibration, frequency and transient response analyses.

Augmented constrained layer damping in plates through the optimal design of a 0-3 viscoelastic composite layer

2018 ◽  
Vol 24 (23) ◽  
pp. 5514-5524 ◽  
Author(s):  
Ambesh Kumar ◽  
Satyajit Panda ◽  
Vivek Narsaria ◽  
Ashish Kumar
Keyword(s):  
Composite Layer ◽  
Shear Deformation Theory ◽  
Viscoelastic Layer ◽  
Damping Capacity ◽  
Geometrical Parameters ◽  
Fe Model ◽  
Constrained Layer Damping ◽  
Rectangular Array ◽  
Viscoelastic Composite ◽  
Over The Top

In this work, a new 0-3 viscoelastic composite (VEC) layer is presented for augmented constrained layer damping of plate vibration. The 0-3 VEC layer comprises a rectangular array of the thin rectangular graphite-wafers embedded within the viscoelastic matrix. The inclusions of graphite-wafers in the constrained 0-3 VEC layer confine the motion of the viscoelastic phase for its reasonable in-plane strains along with the enhanced transverse shear strains. This occurrence of coincidental shear and extensional strains within the viscoelastic phase is supposed to cause augmented damping capacity of the constrained layer, and it is investigated by integrating the constrained 0-3 VEC layer over the top surface of a substrate plate. A finite element (FE) model of the overall plate is developed based on the layer-wise shear deformation theory. Using this FE model, first, a bending analysis of the overall plate is performed to investigate the mechanisms of damping in the use of 0-3 VEC layer. Next, the damping in the overall plate is quantified for different sets of values of the geometrical parameters of the 0-3 VEC layer. These results reveal significant improvement of damping in the plate due to the inclusions of graphite-wafers within the constrained viscoelastic layer. But, the augmentation of damping indicatively depends on the geometrical parameters in the arrangement of the graphite-wafers. So, the 0-3 VEC layer is configured appropriately through an optimization algorithm, and finally, the forced frequency responses of the overall plate are evaluated to demonstrate the augmented attenuation of vibration-amplitude via the inclusions of graphite-wafers within the constrained viscoelastic layer in an optimal manner.

scholarly journals Vibration analysis of a sandwich cylindrical shell in hygrothermal environment

2021 ◽  
Vol 10 (1) ◽  
pp. 414-430
Author(s):  
Chunwei Zhang ◽  
Qiao Jin ◽  
Yansheng Song ◽  
Jingli Wang ◽  
Li Sun ◽  
...  
Keyword(s):  
Cylindrical Shell ◽  
Natural Frequency ◽  
Equations Of Motion ◽  
Single Layer ◽  
Functionally Graded ◽  
Sandwich Shell ◽  
Continuous Change ◽  
Multilayered Structures ◽  
Cylindrical Sandwich Shell ◽  
Vibrational Behavior

Abstract The sandwich structures are three- or multilayered structures such that their mechanical properties are better than each single layer. In the current research, a three-layered cylindrical shell including a functionally graded porous core and two reinforced nanocomposite face sheets resting on the Pasternak foundation is used as model to provide a comprehensive understanding of vibrational behavior of such structures. The core is made of limestone, while the epoxy is utilized as the top and bottom layers’ matrix phase and also it is reinforced by the graphene nanoplatelets (GNPs). The pattern of the GNPs dispersion and the pores distribution play a crucial role at the continuous change of the layers’ properties. The sinusoidal shear deformation shells theory and the Hamilton’s principle are employed to derive the equations of motion for the mentioned cylindrical sandwich shell. Ultimately, the impacts of the model’s geometry, foundation moduli, mode number, and deviatory radius on the vibrational behavior are investigated and discussed. It is revealed that the natural frequency and rotation angle of the sandwich shell are directly related. Moreover, mid-radius to thickness ratio enhancement results in the natural frequency reduction. The results of this study can be helpful for the future investigations in such a broad context. Furthermore, for the pipe factories current study can be effective at their designing procedure.

Buckling of a Circular Cylindrical Web-Stiffened Sandwich Shell Under Axial Compression

1974 ◽  
Vol 18 (01) ◽  
pp. 55-61
Author(s):  
Vincent Volpe ◽  
Youl-Nan Chen ◽  
Joseph Kempner
Keyword(s):  
Axial Compression ◽  
Large Deflection ◽  
Single Layer ◽  
Subsequent Development ◽  
Buckling Load ◽  
Sandwich Shell ◽  
Cylindrical Sandwich Shell ◽  
Axisymmetric Mode ◽  
Shell Equations ◽  
The Mathematical Model

A stability analysis of an infinitely long web-stiffened, circular cylindrical sandwich shell under uniform axial compression is presented. The formulation begins with the establishment of a set of suitable large-deflection shell equations that forms the basis for the subsequent development of the buckling equations. The mathematical model corresponds to two face layers that are considered as thin shells and a thick core that is capable of resisting both transverse shear and circumferential extension. The associated eigenvalue problem is solved. Results show that the lowest buckling load is associated with the axisymmetric mode and is less than one half the buckling load of an equivalent single-layer shell.

High Frequency Vibration Analysis of Automotive Bodies With Panels That Have Attached Viscoelastic Layers

2003 ◽  
Author(s):  
Yoshio Kurosawa ◽  
Hideki Enomoto ◽  
Shuji Matsumura ◽  
Takao Yamaguchi
Keyword(s):  
High Frequency ◽  
Large Scale ◽  
The Body ◽  
Viscoelastic Damping ◽  
Fe Model ◽  
Automotive Body ◽  
Modal Damping ◽  
Practical Tool ◽  
Damping Materials ◽  
Viscoelastic Layers

A technique has been developed for estimating vibrations of an automotive body structures with viscoelastic damping materials using large-scale finite element (FE) model, which will enable us to grasp and to reduce high-frequency road noise (200∼500Hz). In the new technique, first order solutions for modal loss factors are derived applying asymptotic method. This method saves calculation time to estimate modal damping as a practical tool in the design stages of the body structures. Frequency responses were calculated using this technique and the results almost agreed with the test results. This technique can show the effect of the viscoelastic damping materials on the automotive body panels, and it enables the more efficient layout of the viscoelastic damping materials. Further, we clarified damping properties of the automotive body structures under coupled vibration between frames and panels with the viscoelastic damping materials.

Flexure of a cylindrical sandwich shell of variable thickness

1968 ◽  
Vol 4 (5) ◽  
pp. 36-39
Author(s):  
I. M. Pirogov ◽  
F. I. Selitskii
Keyword(s):  
Variable Thickness ◽  
Sandwich Shell ◽  
Cylindrical Sandwich Shell
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