An Analysis of Viscoelastic Damping Characteristics of a Simply-Supported Sandwich Beam

1971 ◽  
Vol 93 (4) ◽  
pp. 1239-1244 ◽  
Author(s):  
A. Chatterjee ◽  
J. R. Baumgarten
Keyword(s):  
Energy Method ◽  
Sandwich Beam ◽  
Core Material ◽  
Viscoelastic Damping ◽  
Experimental Measurements ◽  
Simply Supported ◽  
The Core ◽  
Damping Characteristics ◽  
Viscoelastic Core ◽  
Theoretical Predictions

An energy method is employed to analyze the damping in the fundamental mode of a simply-supported sandwich beam with viscoelastic core material sandwiched between two elastic metallic layers called the facings. The theory developed herein enables one to predict the damped natural frequency and the damping (in terms of logarithmic decrement) of the transverse vibration of a beam of known dimensions, provided the moduli-frequency characteristics of the core material are known. Experimental measurements bear out the accuracy of the theoretical predictions. The theory can very easily be extended for the analysis of higher discrete modes.

Flexural Vibration of Segmented Elastic-Viscoelastic Sandwich Beams

1975 ◽  
Vol 42 (4) ◽  
pp. 897-900
Author(s):  
B. E. Sandman
Keyword(s):  
Steady State ◽  
Numerical Study ◽  
Sandwich Beam ◽  
Flexural Vibration ◽  
Middle Layer ◽  
Resonant Mode ◽  
Sandwich Beams ◽  
Simply Supported ◽  
Viscoelastic Core ◽  
Longitudinal Nonuniformity

A pair of governing differential equations form the basis for the study of steady-state forced vibration of a sandwich beam with longitudinal nonuniformity in the stiffness and mass of the middle layer. The spatial solution for simply supported boundary conditions is obtained by a Fourier analysis of both material and kinematic variations. The solution is utilized in the numerical study of a sandwich beam with a segmented configuration of elastic and viscoelastic core materials. The results exemplify a tuned configuration of core segments for optimum damping of the first resonant mode.

Consideration of Both Extensional and Shear Strain of Core Material in Modal Property Estimation of Sandwich Plates

1995 ◽  
Author(s):  
Byung-Chan Lee ◽  
Kwang-Joon Kim
Keyword(s):  
Shear Strain ◽  
Layer Thickness ◽  
Sandwich Beam ◽  
Base Layer ◽  
Core Material ◽  
Viscoelastic Layer ◽  
Sandwich Plates ◽  
Modal Parameter ◽  
The Core ◽  
Plate Length

Abstract In vibration analysis of sandwich beam/plates, it is often assumed that there occurs shear deformation only, i.e. no extension or compression, in the core viscoelastic layer. Certainly, this assumption may have limitations, for example, with increase of the core thickness or frequency range of vibration. The purpose of this paper is to consider the extentional as well as shear strain of the core for modal parameter estimation of the sandwich plates and to investigate how much error will be caused by neglecting the extension or compression in the core material. Natural frequencies and modal loss factors are estimated for a simply supported square plates under each of the above two assumptions. Nondimensional characteristic equations are formulated and solved for various ratios of the base layer thickness to plate length, core to base layer thickness, and constraining layer to base layer thickness.

Vibration and Damping Analysis of Rectangular Plate With Partially Covered Constrained Viscoelastic Layer

1987 ◽  
Vol 109 (3) ◽  
pp. 241-247 ◽  
Author(s):  
A. K. Lall ◽  
N. T. Asnani ◽  
B. C. Nakra
Keyword(s):  
Loss Factor ◽  
Ritz Method ◽  
Viscoelastic Damping ◽  
Viscoelastic Layer ◽  
Transverse Displacement ◽  
Modal System ◽  
Resonant Frequencies ◽  
Simply Supported ◽  
The Core ◽  
Single Term

The Rayleigh-Ritz method is applied for the damping analysis offlexural vibrations of a simply supported plate, partially covered with constrained viscoelastic damping treatment. The anaysis is carried out in terms of resonant frequencies and associated modal system loss factors. Single-term solutions for respective modes are assumed for the longitudinal displacements of the constraining layer and the transverse displacement of the plate. The variations of the resonant frequency and the associated modal loss factor with the coverage percentage, the coverage location, the core shear modulus and the thickness of the constrained and the constraining layers have been reported.

The Damping Effects of Viscoelastic Materials: Part 1—Transverse Vibrations of Beams With Viscoelastic Coatings

1971 ◽  
Vol 93 (2) ◽  
pp. 645-650 ◽  
Author(s):  
Joseph R. Baumgarten ◽  
Britt K. Pearce
Keyword(s):  
Energy Method ◽  
Composite Beam ◽  
Metal Layer ◽  
Viscoelastic Layer ◽  
Experimental Measurements ◽  
Transverse Vibrations ◽  
Theoretical Predictions ◽  
Rate Of Decay ◽  
Damping Effects ◽  
Viscoelastic Coatings

An energy method similar to Rayleigh’s method is employed to analyze a nonhomogeneous, damped beam composed of an elastic (metal) layer and an unconstrained viscoelastic layer. This analysis is limited to the case of thin free-free beams vibrating freely in the fundamental mode. The theory developed enables one to predict the damped natural frequency and the rate of decay (in terms of logarithmic decrement) of the transverse vibrations of a composite beam of given dimensions and composed of two particular materials. Experimental measurements bear out the fact that theoretical predictions are indeed accurate. Beams with two symmetric elastic coatings are also considered and their damping effects are compared to those of coating applied to one side only.

Nonlinear, Damped Vibrations of Sandwich Plates With Time-Dependent Temperature

1993 ◽  
Author(s):  
S. Lukasiewicz ◽  
Z. Q. Xia
Keyword(s):  
Sandwich Plate ◽  
Rapid Change ◽  
Time Dependent ◽  
Viscoelastic Damping ◽  
Sandwich Plates ◽  
Simply Supported ◽  
Geometrical Nonlinearities ◽  
The Core

Abstract The paper studies the effect of the rapid change of temperature on the vibrations of simply supported sandwich plates. It has been taken into consideration that the properties of the facings and of the core of the sandwich plate materials change with the change of the temperature. The effects of the viscoelastic damping and geometrical nonlinearities on the behaviour of the plate have also been included. It was found that the rapid change of temperature affects the amplitude and frequency of the vibrations.

Static Response of Stiff-Cored Unsymmetric Sandwich Beams

1976 ◽  
Vol 98 (2) ◽  
pp. 391-396 ◽  
Author(s):  
D. K. Rao
Keyword(s):  
Variational Method ◽  
Flexural Rigidity ◽  
Sandwich Beam ◽  
Sandwich Beams ◽  
Static Response ◽  
Simply Supported ◽  
The Core ◽  
Distributed Load ◽  
Very High ◽  
Maximum Stresses

Improved equations governing the deflection of an unsymmetric sandwich beam (which include the effect of extensional and bending rigidities of its stiff core) are derived using a variational method. The effect of face-thickness ratio on the contribution of the core to the overall flexural rigidity is studied. Numerical results for simply supported and fixed-fixed beams subjected to a uniformly distributed load are obtained by using Laplace transforms. These results show that ignoring the bending and extensional effects of a stiff core can cause errors in maximum deflections as high as 20 percent. The corresponding errors in stresses are very high, and they vary from 10 to 150 percent. Hence, it is suggested that the extensional and bending effects of the core should be taken into account when one is interested in calculating the maximum stresses in stiff-cored beams.

scholarly journals Investigating the influence of the core material on the mechanical performance of a nitinol wire wrapped helical auxetic yarn

2021 ◽  
pp. 030932472110270
Author(s):  
Nadimul Haque Faisal ◽  
Andrew Fowlie ◽  
Joe Connell ◽  
Sean Mackenzie ◽  
Ryan Noble ◽  
...  
Keyword(s):  
Analytical Model ◽  
Mechanical Performance ◽  
Poisson Ratio ◽  
Axial Strain ◽  
Impact Resistance ◽  
Tensile Tests ◽  
Core Material ◽  
The Core ◽  
Nitinol Wire ◽  
Theoretical Predictions

Helical Auxetic Yarns (HAYs) can be used in a variety of applications from healthcare to blast and impact resistance. This work focuses on the effect of the use of different core materials (e.g. rubber, polyurethane, polytetrafluoroethylene/teflon, polypropylene, polyetheretherketone, polycarbonate, acetal) with a nitinol wire wrap component on the maximum Negative Poisson Ratio (NPR) produced and thus the auxetic performance of Helical Auxetic Yarns (HAYs). From the analytical model, it was found that an acetal core produced the largest NPR when compared to the other six materials. The trend obtained from the experimental tensile tests (validation) correlated closely with the theoretical predictions of the NPR as axial strain was increased. The experimental method presented a maximum NPR at an average axial strain of 0.148 which was close to the strain of 0.155 predicted by theory. However, the maximum experimental NPR was significantly lower than that predicted by the analytical model.

scholarly journals Nonlinear Vibration Behavior of Sandwich Beams With Entangled Fiber Core Material

2013 ◽  
Author(s):  
Elsa Piollet ◽  
Guilhem Michon ◽  
Dominique Poquillon
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Virtual Work ◽  
Equations Of Motion ◽  
Sandwich Beam ◽  
Experimental Tests ◽  
Core Material ◽  
Sandwich Beams ◽  
Fiber Core ◽  
The Core

In this paper, the use of entangled cross-linked fibers as core material in vibrating sandwich beams is investigated. The aim is to analyze the effect of this specific core material in terms of damping. The dynamic shear properties of the material are first studied experimentally. The shear modulus is shown to decrease with increasing shear strain amplitude at low shear strains. To include an amplitude dependency of the core material properties in the sandwich beam behavior, an analytical model is proposed. The equations of motion are derived using Lagrange’s equations. The shearing of the core is introduced in the equations through the use of virtual work to allow any relationship between shear stress and shear strain, including damping and nonlinearities. Experimental tests are carried out on sandwich beams with entangled fiber core material. The Frequency Response Function obtained exhibits decreasing resonant frequency and peak amplitude with increasing load amplitude. This softening behavior is consistent with the decreasing shear modulus. The proposed model is used take into account the softening nonlinearity. The FRF is reproduced with a linearly decreasing shear modulus and linearly increasing loss factor.

scholarly journals Dynamic analysis of sandwich beam with viscoelastic core under moving loads

Mechanika ◽  
2020 ◽  
Vol 26 (4) ◽  
pp. 325-330
Author(s):  
Sabiha Tekili ◽  
Youcef KHADRI ◽  
Yacine KARMI
Keyword(s):  
Sandwich Beam ◽  
Numerical Approach ◽  
Dynamic Responses ◽  
Viscoelastic Damping ◽  
Integration Scheme ◽  
Superposition Method ◽  
Moving Loads ◽  
The Finite Element Method ◽  
Modal Superposition Method ◽  
Viscoelastic Core

In this article, numerical approach is proposedfor dynamic behavior of symmetrical sandwich beams with viscoelastic core under movingload using the Hamilton's principle formulation and the finite element method solution. The dynamic responses are obtained for different configurations using the modal superposition method and the implicit Newmark integration scheme. The analysis shows that the viscoelastic damping has a significant effect on the vibration behavior involving the improvement of the damping of the structure. The parametric study of the effect of the configuration parameters shows that the sandwich structure has more dissipative capacities of vibratory energy by adopting adequate configurations to the structure.

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