The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Holger Steeb - One of the best experts on this subject based on the ideXlab platform.
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time harmonic waves in a thermo Viscoelastic Material with voids
Journal of Vibration and Control, 2014Co-Authors: S K Tomar, J Bhagwan, Holger SteebAbstract:In the present work, we study the propagation of time harmonic waves in an infinite thermo-Viscoelastic Material with voids. Four basic waves traveling with distinct speeds are found, out of which, one is a shear wave, and the remaining three are dilatational waves. All the dilatational waves are found to be coupled due to the presence of voids and thermal properties of the Material, while the shear wave is found to be uncoupled and travels independently with the speed that exists in a linear Viscoelastic medium. The speeds of propagation of all the waves are found to be complex valued and frequency dependent. Reflection phenomena of these waves from a mechanically stress-free and thermally insulated plane boundary of a thermo-Viscoelastic half-space with voids have been investigated. Formulae for amplitudes and energy ratios corresponding to various reflected waves have been obtained and are presented in closed form. Numerical computations are performed for a specific model, and the results obtained are ...
Jing Luo - One of the best experts on this subject based on the ideXlab platform.
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a finite element model for the vibration analysis of sandwich beam with frequency dependent Viscoelastic Material core
Materials, 2019Co-Authors: Zhicheng Huang, Xingguo Wang, Fulei Chu, Jing LuoAbstract:In this work, a finite element model was developed for vibration analysis of sandwich beam with a Viscoelastic Material core sandwiched between two elastic layers. The frequency-dependent Viscoelastic dynamics of the sandwich beam were investigated by using finite element analysis and experimental validation. The stiffness and damping of the Viscoelastic Material core is frequency-dependent, which results in complex vibration modes of the sandwich beam system. A third order seven parameter Biot model was used to describe the frequency-dependent Viscoelastic behavior, which was then incorporated with the finite elements of the sandwich beam. Considering the parameters identification, a strategy to determine the parameters of the Biot model has been outlined, and the curve fitting results closely follow the experiment. With identified model parameters, numerical simulations were carried out to predict the vibration and damping behavior in the first three vibration modes, and the results showed that the finite model presented here had good accuracy and efficiency in the specific frequency range of interest. The experimental testing on the Viscoelastic sandwich beam validated the numerical predication. The experimental results also showed that the finite element modeling method of sandwich beams that was proposed was correct, simple and effective.
V. V. Shumilova - One of the best experts on this subject based on the ideXlab platform.
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plane acoustic wave propagation through a composite of elastic and kelvin voigt Viscoelastic Material layers
Mechanics of Solids, 2017Co-Authors: A. S. Shamaev, V. V. ShumilovaAbstract:The problem of plane wave propagation through a plane composite layer of thickness h is considered. The composite consists of periodically repeated elastic and Kelvin–Voigt Viscoelastic Material layers, and all layers are either parallel or perpendicular to the incident wave front. Moreover, it is assumed that the thickness of each separate layer of the composite is much less than the acoustic wave length and the thickness h of the entire composite. We study the problem by using a homogenized model of the composite, which allows us to find the reflection and transmission factors and the variation in the sound intensity level as it propagates though the composite layer of thickness h.
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Plane acoustic wave propagation through a composite of elastic and Kelvin–Voigt Viscoelastic Material layers
Mechanics of Solids, 2017Co-Authors: A. S. Shamaev, V. V. ShumilovaAbstract:The problem of plane wave propagation through a plane composite layer of thickness h is considered. The composite consists of periodically repeated elastic and Kelvin–Voigt Viscoelastic Material layers, and all layers are either parallel or perpendicular to the incident wave front. Moreover, it is assumed that the thickness of each separate layer of the composite is much less than the acoustic wave length and the thickness h of the entire composite. We study the problem by using a homogenized model of the composite, which allows us to find the reflection and transmission factors and the variation in the sound intensity level as it propagates though the composite layer of thickness h .
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AVERAGING OF ACOUSTIC EQUATION FOR PARTIALLY PERFORATED Viscoelastic Material WITH CHANNELS FILLED BY A LIQUID
Journal of Mathematical Sciences, 2013Co-Authors: V. V. ShumilovaAbstract:Acoustic equations for combined media consisting of partially perforated Viscoelastic Material and viscous incompressible liquid filling pores are considered. An averaged model is constructed for the model under consideration, and boundary conditions connecting equations of the obtained averaged model on the boundary between solid Viscoelastic Material and porous Viscoelastic Material filled by a viscous incompressible liquid are found. The convergence of limit problems to the solution of corresponding averaged problem with respect to the norm of the space L 2 is proved.
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averaging the acoustics equations for a Viscoelastic Material with channels filled with a viscous compressible fluid
Fluid Dynamics, 2011Co-Authors: A. S. Shamaev, V. V. ShumilovaAbstract:A mathematical model describing small oscillations of a combined medium consisting of an ɛ-periodic porous Viscoelastic Material and a viscous compressible fluid filling the pores is considered. For this model an effective averaged model is developed and the convergence of the solutions of prelimiting problems, as ɛ → 0, to the solution of the averaged problem in the L2 space norm is proved.
Jan Freundlich - One of the best experts on this subject based on the ideXlab platform.
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vibrations of a simply supported beam with a fractional Viscoelastic Material model supports movement excitation
Shock and Vibration, 2013Co-Authors: Jan FreundlichAbstract:The paper presents vibration analysis of a simply supported beam with a fractional order Viscoelastic Material model. The Bernoulli-Euler beam model is considered. The beam is excited by the supports movement. The Riemann - Liouville frac- tional derivative of order 0 <α 1 is applied. In the first stage, the steady-state vibrations of the beam are analyzed and therefore the Riemann - Liouville fractional derivative with lower terminal at −∞ is assumed. This assumption simplifies solution of the fractional differential equations and enables us to directly obtain amplitude-frequency characteristics of the examined system. The characteristics are obtained for various values of fractional derivative of order α and values of the Voigt Material model parameters. The studies show that the selection of appropriate damping coefficients and fractional derivative order of damping model enables us to fit more accurately dynamic characteristic of the beam in comparison with using integer order derivative damping model.
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Vibrations of a Simply Supported Beam with a Fractional Viscoelastic Material Model – Supports Movement Excitation
Shock and Vibration, 2013Co-Authors: Jan FreundlichAbstract:The paper presents vibration analysis of a simply supported beam with a fractional order Viscoelastic Material model. The Bernoulli-Euler beam model is considered. The beam is excited by the supports movement. The Riemann – Liouville fractional derivative of order 0 α ⩽ 1 is applied. In the first stage, the steady-state vibrations of the beam are analyzed and therefore the Riemann – Liouville fractional derivative with lower terminal at −∞ is assumed. This assumption simplifies solution of the fractional differential equations and enables us to directly obtain amplitude-frequency characteristics of the examined system. The characteristics are obtained for various values of fractional derivative of order α and values of the Voigt Material model parameters. The studies show that the selection of appropriate damping coefficients and fractional derivative order of damping model enables us to fit more accurately dynamic characteristic of the beam in comparison with using integer order derivative damping model.
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Vibrations of a simply supported beam with a fractional derivative order Viscoelastic Material model - Supports movement excitation
2012Co-Authors: Jan FreundlichAbstract:The paper presents vibration analysis of a simply supported beam with a fractional order Viscoelastic Material model. The Bernoulli-Euler beam model is considered. The beam is excited by the supports movement. The Riemann –Liouville fractional derivative of order 0 < α ≤ 1 is applied. In the first stage, the steady-state vibrations of the beam are analyzed and therefore the Riemann –Liouville fractional derivative with lower terminal at -∞ is assumed. This assumption simplifies solution of the fractional differential equations and enables us to directly obtain amplitude-frequency characteristics of the examined system. The characteristics are performed for various values of fractional derivative of order a and values of the Voigt Material model parameters.
Wilkins Aquino - One of the best experts on this subject based on the ideXlab platform.
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inverse Viscoelastic Material characterization using pod reduced order modeling in acoustic structure interaction
Computer Methods in Applied Mechanics and Engineering, 2009Co-Authors: John C Brigham, Wilkins AquinoAbstract:Abstract A strategy is presented for applying the proper orthogonal decomposition (POD) technique for model reduction in computational inverse solution strategies for Viscoelastic Material characterization. POD is used to derive a basis of optimal dimension from a selection of possible solution fields which are generated through a traditional acoustic–structure interaction finite element model for a given vibroacoustic experiment. The POD bases are applied with the Galerkin weak-form finite element method to create a reduced-order numerical model with decreased computational cost, but which still maintains accuracy close to that of the original full-order finite element model. The reduced-order model is then combined with a global optimization technique to identify estimates to the Viscoelastic Material properties of a fluid immersed solid from vibroacoustic tests. A strategy is also presented to select the Viscoelastic parameters of the initial full-order analyses used to create the POD bases. The selection process is shown through an example to maximize the generalization capabilities of the reduced-order model over the Material search space for a minimal number of full-order analyses. Two examples are then presented in which the parameters of rheological Viscoelastic models are identified for solids immersed in water, which are subject to a steady-state harmonic pressure while the acoustic response is measured at a point in the surrounding fluid. The POD reduced-order models were able to generalize over the Material search domains for the inverse problems. Therefore, the reduced-order solution strategy was capable of identifying accurate estimates to the Viscoelastic behavior of the solids with minimal computational expense.
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inverse estimation of Viscoelastic Material properties for solids immersed in fluids using vibroacoustic techniques
Journal of Applied Physics, 2007Co-Authors: John C Brigham, Wilkins Aquino, F G Mitri, James F Greenleaf, Mostafa FatemiAbstract:This work presents an approach to inversely determine Material properties for solids immersed in fluids through the use of steady-state dynamic response. The methodology uses measured acoustic pressure amplitudes in the fluid surrounding a structure being vibrated with a harmonic force to determine the parameters for elastic and Viscoelastic Material models. Steady-state dynamic finite element analysis is used to compute the frequency response function of homogeneous and heterogeneous solids. The frequency response is then used to inversely estimate Material parameters. In order to solve the inverse problem, an optimization method is presented which combines the global search capabilities of the random search method with the reduced computational time of a surrogate model approach. Through numerical and laboratory experiments, this work shows that acoustic emissions hold sufficient information for quantifying both elastic and Viscoelastic Material behaviors. Furthermore, the examples show that the surroga...
