Examinando por Materia "finite element method"

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    Finite element modeling of micropolar-based phononic crystals
    (Elsevier BV, 2019-11-11) Guarín-Zapata N.; Gomez J.; Valencia C.; Dargush G.F.; Hadjesfandiari A.R.; Mecánica Aplicada
    The performance of a Cosserat/micropolar solid as a numerical vehicle to represent dispersive media is explored. The study is conducted using the finite element method with emphasis on Hermiticity, positive definiteness, principle of virtual work and Bloch–Floquet boundary conditions. The periodic boundary conditions are given for both translational and rotational degrees of freedom and for the associated force- and couple-traction vectors. Results in terms of band structures for different material cells and mechanical parameters are provided. © 2019 Elsevier B.V.
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    Modeling added spatial variability due to soil improvement: Coupling FEM with binary random fields for seismic risk analysis
    (Elsevier Ltd, 2018-01-01) Montoya-Noguera, Silvana; Lopez-Caballero, Fernando; Mecánica Aplicada
    A binary mixture homogenization model is proposed for predicting the effects on liquefaction-induced settlement after soil improvement based on the consideration of the added spatial variability between the natural and the treated soil. A 2D finite element model of an inelastic structure founded on a shallow foundation was coupled with a binary random field. Nonlinear soil behavior is used and the model is tested for different mesh size, model parameters and input motions. Historical evidence as well as physical and numerical modeling indicate that improved sites present less liquefaction and ground deformation. In most cases this improvement is modeled as homogeneous; however, in-situ measurements evidence the high level of heterogeneity in the deposit. Inherent spatial variability in the soil and the application of some soil improvement techniques such as biogrouting and Bentonite permeations will necessary introduce heterogeneity in the soil deposit shown as clusters of the treated material in the natural soil. Hence, in this study, improvement zones are regarded as a two-phase mixture that will present a nonlinear relation due to the level of complexity of seismic liquefaction and the consequent settlement in a structure. This relation is greatly affected by the mechanical behavior of the soils used and the input motion. The effect on the latter can be efficiently related to the equivalent wave period as the proposed homogenization model depends on the stiffness demand of the input motion. © 2017 Elsevier Ltd