Examinando por Autor "Garcia, Manuel"

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    Fluid-structure coupling using lattice-Boltzmann and fixed-grid FEM
    (ELSEVIER SCIENCE BV, 2011-08-01) Garcia, Manuel; Gutierrez, Jorge; Rueda, Nestor; Mecánica Aplicada
    This paper presents a method for the fluid-structure interaction by a hybrid approach that uses lattice-Boltzmann method (LBM) for the fluid dynamics analysis and fixed-grid FEM (FGFEM) for the structural analysis. The method is implemented in a high performance platform using GPUs to provide a high level of interactivity with the simulation. The solution uses the same Cartesian grid for both solvers. The coupling between both methods is accomplished by mapping the macroscopic pressure, velocity or momentum values from the LBM simulation into the corresponding nodes of the FGFEM structural problem. In spite of being based on a Cartesian grid, both solvers take into account the effect of curve boundaries. Also the effect of a moving boundary is considered in the fluid simulations. The examples presented in this paper show that the accuracy of the solution is as the same level of the finite volume method of the finite element method. On the other hand, the performance of the parallel implementation of the proposed method is of the order that allows real-time visualisation of the computing values for two-dimensional problems. © 2011 Elsevier B.V. All rights reserved.
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    Quaternion and octonion-based finite element analysis methods for computing multiple first order derivatives
    (Elsevier Inc., 2019-11-15) Aristizabal, Mauricio; Ramirez-Tamayo, Daniel; Garcia, Manuel; Aguirre-Mesa, Andres; Montoya, Arturo; Millwater, Harry; Mecánica Aplicada
    The complex Taylor series expansion method for computing accurate first order derivatives is extended in this work to quaternion, octonion and any order Cayley-Dickson algebra. The advantage of this new approach is that highly accurate multiple first order derivatives can be obtained in a single analysis. Quaternion and octonion-based finite element analysis methods were developed in order to compute up to three (quaternion) and up to seven (octonion) first order derivatives of shape, material properties, and/or loading conditions in a single analysis. The traditional finite element formulation was modified such that each degree-of-freedom was augmented with three or seven additional imaginary nodes. The quaternion and octonion-based methods were integrated within the Abaqus commercial finite element code through a user element subroutine. Numerical examples are presented for thermal conductivity and linear elasticity; however, the methodology is general. The results indicate that the quaternion and octonion-based methods provide derivatives of the same high accuracy as the complex finite element method but are significantly more efficient. A Fortran code to solve a simple seven variable quaternion example is given in the Appendix. (C) 2019 Elsevier Inc. All rights reserved.
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    Spring-particle model for hyperelastic cloth
    (UNIV NAC COLOMBIA, FAC NAC MINAS, 2007-03-01) Garcia, Manuel; Gomez, Mario; Ruiz, Oscar; Boulanger, Pierre; Mecánica Aplicada
    This article presents a computational model to simulate the deformation of hyperelastic fabrics. The model is based on a spring-particle approach and it simulates the interaction of a textile tissue with a forming body. The fabric is represented by rectangular meshes of springs. This fact enables the model to behave orthotropically and therefore it is possible to simulate the warp and weft properties. The constitutive relations preserve the natural hyperelastic capabilities of the cloth. In the model developed herein, initially the cloth lies in its relaxed un-deformed state. Then it is given an initial deformation that guarantees no contact nor intersection with the forming rigid body. Finally, the deformed cloth is realised, and moves iteratively towards an equilibrium location. The final equilibrium location is reached when the internal forces are balanced by the external contact forces caused by the rigid object. This is achieved when the stop criterion has been satisfied.