scholarly journals Torsional Damping Characteristics of Rectangular Three-Layered Rods with Viscoelastic Layers. Experimental Evaluation of Sandwich Rod and Covered Rod.

1991 ◽  
Vol 34 (4) ◽  
pp. 466-474
Author(s):  
Hiromi DEWA
Keyword(s):  
Experimental Evaluation ◽  
Damping Characteristics ◽  
Torsional Damping ◽  
Viscoelastic Layers

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.

Vibration Analyses of Cylindrical Hybrid Panel with Viscoelastic Layer Based on Layerwise Finite Elements

2006 ◽  
Vol 324-325 ◽  
pp. 699-702 ◽  
Author(s):  
Il Kwon Oh ◽  
Tai Hong Cheng
Keyword(s):  
Finite Element ◽  
Virtual Work ◽  
Structural Parameters ◽  
Element Model ◽  
Viscoelastic Layer ◽  
Normal Strain ◽  
Constrained Layer Damping ◽  
Damping Characteristics ◽  
Viscoelastic Layers ◽  
Damping Treatments

Based on full layerwise displacement shell theory, the vibration and damping characteristics of cylindrical sandwiched panels with viscoelastic layers are investigated. The transverse shear deformation and the normal strain of the cylindrical hybrid panels are fully taken into account for the structural damping modeling. The layerwise finite element model is formulated by using Hamilton’s virtual work principle and the cylindrical curvature of hybrid panels is exactly modeled. Modal loss factor and frequency response functions are analyzed for various structural parameters of cylindrical sandwich panels. Present results show that the full layerwise finite element method can accurately predict the vibration and damping characteristics of the cylindrical hybrid panels with surface damping treatments and constrained layer damping.

Vibration Damping Characteristics of Multilayered Beams With Constrained Viscoelastic Layers

1976 ◽  
Vol 98 (3) ◽  
pp. 895-901 ◽  
Author(s):  
N. T. Asnani ◽  
B. C. Nakra
Keyword(s):  
Thickness Ratio ◽  
Static Stiffness ◽  
Constant Weight ◽  
Damping Characteristics ◽  
Layered Beams ◽  
Constant Size ◽  
Number Of Layers ◽  
Maximum Value ◽  
Viscoelastic Layers ◽  
Elastic Layers

Results are reported on damping effectiveness during flexural vibrations of multi-layered beams, with constrained viscoelastic layers. These are given for simply supported beams with number of layers up to 15, all viscoelastic layers being identical. The elastic layers are also taken to be similar to one another. The influence of number of layers and thickness ratio of viscoelastic to elastic layers, for constant size, constant weight and constant static stiffness criteria, has been studied. In order to obtain maximum value of loss factor or of displacement response effectiveness for multilayered beams, under specific requirements of static stiffness, weight and size, a suitable choice of number of layers and thickness ratio of viscoelastic to elastic layers, is found to be important.

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 Possibilities of the Additional Damping of Unidirectional Fiber Composites by Implementation of Viscoelastic Neoprene and Rubber Layers

2017 ◽  
Vol 2017 ◽  
pp. 1-15
Author(s):  
Petr Kulhavy ◽  
Michal Petru ◽  
Martina Syrovatkova
Keyword(s):  
Transfer Function ◽  
Carbon Fibers ◽  
Fiber Composites ◽  
Layered Shell ◽  
Fem Model ◽  
Damping Characteristics ◽  
Damping Materials ◽  
The Individual ◽  
The Right ◽  
Viscoelastic Layers

The aim of the presented work is to assess modal, transmission, and damping characteristics of layered carbon plates. The base is to carry experimental analysis verified by FEM model, which evaluates the vibration transfer of tested composites and describes possibilities of additional damping by implementation of viscoelastic layers. Preimpregnated carbon fibers known as prepreg were used for creation of the samples composed of four (2 constant and 2 variable) layers. The task was to assess impact of changing the fiber orientation on the transfer function and individual modal characteristics. As another option, testing of some additional damping materials was included. Neoprene and thin rubber coat were added as an outside damping element when the neoprene ply was inserted also among the layers. Expected dependence of the plies orientation onto the shape of the transfer function and even swapping of some of MOD characters (bending, torsion, and their combinations) have been found. The use of the additional damping materials is also possible but the right combination of the individual plies layout and stacking sequence is the most significant part. The results had been statistically analyzed and showed that the created layered shell FE models could be used to describe the behavior.

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