Francisco Javier Montáns

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A fully nonlinear finite-element (FE) model is developed to investigate the impact of hysteretic and viscous material behavior on the downhole motion recorded by an array at a large-scale seismic test site in Lotung, Taiwan, during the earthquake of May 20, 1986. A stick model with the same spatial interpolation accuracy as a three-dimensional FE model is(More)
SUMMARY In this paper an algorithm for large strain elasto-plasticity with isotropic hyperelasticity based on the multiplicative decomposition is formulated. The algorithm includes a (possible) constitutive equation for the plastic spin and mixed hardening in which the principal stress and principal backstress directions are not necessarily preserved. It is(More)
A 3D finite-element model is developed to study soil-structure interaction (SSI) effects at a Large-Scale Seismic Test (LSST) site in Lotung, Taiwan, during the earthquake of May 20, 1986. Analyses are carried out by direct method incorporating a 1/4-scale nuclear plant containment structure. The containment structure is modeled as a linearly elastic(More)
Efficient and accurate simulation of the deformations in anisotropic metallic sheets requires a constitutive model and an accompanying algorithm at large strains which take into account the anisotropy of both the elastic and plastic material behaviors, as well as their evolution with plastic strains. Recently we proposed such a constitutive model based on(More)
A constitutive theory for orthotropic materials is briefly summarized. The constitutive theory allows for anisotropy of the elastic response and anisotropy resulting from both the yield function and the kinematic hardening. The formulation also includes a constitutive theory, thermodynamically consistent, for the plastic spin and the re-orientation of the(More)
In this paper we present a model and a fully implicit algorithm for large strain anisotropic elasto-plasticity with mixed hardening in which the elastic anisotropy is taken into account. The formulation is developed using hyperelasticity in terms of logarithmic strains, the multiplicative decomposition of the deformation gradient into an elastic and a(More)
We consider the modelling of large strain anisotropic plasticity based on hyperelasticity, the multiplicative decomposition into the elastic and plastic deformation gradients, and the use of the logarithmic strain measure and its work-conjugate stress measure. The integration of the plastic deformation gradient is performed using an exponential mapping.(More)
What-You-Prescribe-Is-What-You-Get (WYPIWYG) procedures are a novel and general phenomenological approach to modelling the behavior of soft materials, applicable to biological tissues in particular. For the hyperelastic case, these procedures solve numerically the nonlinear elastic material determination problem. In this paper we show that they can be(More)
We briefly compare three algorithms for large strain elastoplastic analysis in which the logarithmic strain tensor is used to measure the deformations. The first and second algorithms are based on using, respectively, the elastic stretch matrices in the right basis and left basis of the polar decomposition of the trial elastic deformation gradient, and the(More)
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