نتایج جستجو برای: poroelastic media

تعداد نتایج: 281426  

2006
Jianwen Liang Hongbing You Vincent W. Lee

The scattering of SV waves by a canyon in a fluid-saturated, poroelastic layered half-space is modeled using the indirect boundary element method in the frequency domain. The free-field responses are calculated to determine the displacements and stresses at the surface of the canyon, and fictitious distributed loads are then applied at the surface of the canyon in the free field to calculate th...

2012
Jingyi Chen

The nearly perfectly matched layer (NPML) method has been successfully applied to electromagnetic and elastodynamic wave equations including elastic isotropic and anisotropic media types to absorb spurious arrivals reflected from introduced boundaries in a number of numerical solution methods. It has been shown to be extremely satisfactory for this purpose. In this paper, a first-order velocity...

2010
Guillaume Chiavassa Bruno Lombard Joël Piraux

A numerical method is proposed to simulate the propagation of transient poroelastic waves across 2D heterogeneous media, in the low frequency range. A velocity-stress formulation of Biot’s equations is followed, leading to a first-order system of partial differential equations. This system is splitted in two parts: a propagative one discretized by a fourth-order ADER scheme, and a diffusive one...

1997
Anthony L. Endres Rosemary J. Knight

Inclusion-based formulations allow an explicit description of pore geometry by viewing porous rocks as a solid matrix with embedded inclusions representing individual pores. The assumption commonly used in these formulations that there is no fluid pressure communication between pores is reasonable for liquid-filled rocks measured at high frequencies; however, complete fluid pressure communicati...

Journal: :journal of computational applied mechanics 0
s. fallahzadeh r. m.sc., faculty of mechanical engineering, k.n. toosi university of technology, tehran, iran m. shariyat professor, faculty of mechanical engineering, k.n. toosi university of technology, tehran, iran

the present study is the first to analyze the dynamic response of a poroelastic beam subjected to a moving force. moreover, the influences of attached mass-spring systems and non-ideal supports (with local movements in the supporting points or base due to the presence of factors such as gaps, unbalanced masses, and friction or seismic excitations) on the responses were investigated. non-ideal s...

Journal: :Ultrasound in medicine & biology 2005
Raffaella Righetti Jonathan Ophir Thomas A Krouskop

The feasibility of imaging the permeability and Poisson's ratio time-constant of porous media was investigated. The study involved the following steps. First, poroelastograms were generated from porous tofu phantoms under sustained compression. The sample materials used for the experiments were previously characterized through independent mechanical measurements. Second, corresponding Poisson's...

2011
Boris Gurevich

Recently, Hashin-Shtrikman bounds for bulk and shear moduli of elastic composites have been extended to the moduli of composite viscoelastic media. Since viscoelastic moduli are complex, the viscoelastic bounds form a closed curve on a complex plane. We apply these general viscoelastic bounds to a particular case of a porous solid saturated with a Newtonian fluid. Our analysis shows that for po...

2014
L. C. Cardoso J. Dias Rodrigues Roberto Frias

In this paper a numerical model to study the vibro-acoustic behavior of a laminated plate backed by a poroelastic foam layer is developed. Such approach consists on a coupled mitigation strategy aiming either mechanical vibration suppression or acoustic attenuation as well. The laminated plate model consists of fiber laminae with interleaved viscoelastic layers in standard constrained or integr...

Journal: :The Journal of the Acoustical Society of America 2010
Brian T Hefner Darrell R Jackson

While Biot theory can successfully account for the dispersion observed in sand sediments, the attenuation at high frequencies has been observed to increase more rapidly than Biot theory would predict. In an effort to account for this additional loss, perturbation theory is applied to Biot's poroelastic equations to model the loss due to the scattering of energy from heterogeneities in the sedim...

2000
Tim Harrigan

In the field of elastography [l], biological tissues are typically assumed to be purely linear elastic solids. However, several tissues including been known to be poroelastic. We recently developed brain, cartilage and edematous soft tissues, have long a method to estimate the local Poisson's ratio in linear elastic solids [2]. In the current study we use the same method to measure the time-dep...

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