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Finite Element Analysis On Dynamic Response Of Saturated Elasto-viscoplastic Porous Media

Posted on:2006-09-15Degree:MasterType:Thesis
Country:ChinaCandidate:N B JiangFull Text:PDF
GTID:2120360155472315Subject:Engineering Mechanics
Abstract/Summary:PDF Full Text Request
The saturated porous media model, which is based on the mixture theory inmodern continuum mechanics frame, is satisfactory in both mathematics and physics.Nowadays, it has been accepted by more and more people. The finite element analysis isone of the important methods in the investigation on dynamic response of biphasicsaturated porous media model.  Firstly, the paper has reviewed the developments of biphasic saturated porousmedia model and its numerical analysis methods.Secondly, in the framework of incompressible fluid-saturated porous media modeldeveloped from mixtures theories, an initial and boundary value problem is presentedfor one-dimensional dynamic response of porous media. Analytical solutions areattained, with use of Laplace transform and convolution theorem, for the transient wavemotion in saturated porous media under arbitrary stress boundary condition anddisplacement boundary condition, respectively. Through several numerical illustratingexamples, it is demonstrated that the wave motion in saturated porous media is acoupled process of the waves in the skeleton and interstitial fluid, and the apparentvisco-elasticity of saturated porous media is endowed.Thirdly, based on incompressible fluid-saturated porous media model developedfrom mixtures theories, solid skeleton was viewed as elasto-plastic material,and thedynamic governing equations of elasto-plastic saturated porous media model wasestablished, which describe the coupling between the solid deformation and fluid flow.A penalty finite element formulation was attained with using Galerkin weighted residualmethod, and an iterative scheme was designed to solve the nonlinear finite elementsystem equations. The designed two-dimensional finite element program with thecorresponding methods includes rectangular elements for plane stress, plane strain andaxisymmetric problems. Through a numerical example, the displacement, stress andplastic zone of the solid skeleton, as while as the flow velocity and pore pressure ofinterstitial fluid in the porous media under dynamic loading were presented.Finally, viscoplasticity was introduced as a general procedure to regularze theelasto-plastic porous solid, and an elasto-viscoplastic saturated porous media model wasestablished. The differences in finite element methods between elasto-plastic andelasto-viscoplastic model were indicated. Moreover, the restrictionof time-step size wasdiscussed. The elasto-plastic finite element program was also changed toelasto-viscoplastic one. Through several numerical examples, the satisfactory resultswere attained, and the dynamic response property of saturated porous media as while asthe rate-dependent propertyof elasto-viscoplastic solid skeletonwas presented.
Keywords/Search Tags:porous media dynamics, fluid-solid coupling effect, analytical solution elasto-viscoplastic, FEM
PDF Full Text Request
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