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Documents published in Scipedia

• Advances in the particle finite element method for fluid-structure interaction problems

  E. Oñate, S. Idelsohn, M. Celigueta, R. Rossi

  Computational Mechanics (2006). Vol. 6, pp. 41-62

  
  

  Abstract

  We present a general formulation for analysis of fluid-structure interaction problems using the particle finite element method (PFEM). The key feature of the PFEM is the use of a Lagrangian description to model the motion of nodes (particles) in both the fluid and the structure domains. Nodes are thus viewed as particles which can freely move and even separate from the main analysis domain representing, for instance, the effect of water drops. A mesh connects the nodes defining the discretized domain where the governing equations, expressed in an integral from, are solved as in the standard FEM. The necessary stabilization for dealing with the incompressibility of the fluid is introduced via the finite calculus (FIC) method. A fractional step scheme for the transient coupled fluid-structure solution is described. Examples of application of the PFEM to solve a number of fluid-structure interaction problems involving large motions of the free surface and splashing of waves are presented.

  Abstract
  We present a general formulation for analysis of fluid-structure interaction problems using the particle finite element method (PFEM). The key feature of the PFEM is the use [...]

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• The rotation-free BST shell element for linearized buckling analysis of steel structures

  A. Agüero, F. Pallarés, E. Oñate

  Int. J. Computational Methods in Engineering Science and Mechanics (2006). Vol. 7 (3), pp. 209-215

  
  

  Abstract

  In this paper the ability of the basic shell triangular (BST) element to perform linearized buckling analysis is evaluated. The results have been compared with analytical solutions and other finite elements in the literature, such as ANDES3, ANDES4, QSEL, FFQC and BCIZ. This type of analysis is applied to the design of steel structures to obtain the collapse load of panels using the effective width of the plate. In this approach, which is currently recommended by most of the design standards, a semi-empirical/analytical method is used to take into account the nonlinear geometric and material behavior, geometric imperfections and residual stresses. To obtain the critical loads two methods have been mainly applied: the finite strip method and the finite element method, which is more appropriate to deal with any boundary condition and loading pattern. In practice, to obtain the local and distortional buckling, some assumptions related to the interaction between plates are made in order to obtain practical formulae that can be applied; these simplifications can lead to unsafe results, so the linearized buckling analysis must be carried out in a proper way, taking into account the interactions. It is concluded that the BST element presents an excellent behavior to predict the critical loads in compression and shear, and therefore this element must be utilized in future codes when this type of analysis turn out to be mandatory.

  Abstract
  In this paper the ability of the basic shell triangular (BST) element to perform linearized buckling analysis is evaluated. The results have been compared with analytical [...]

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• Simulación de problemas de desgaste, en la interacción herramienta de corte terreno, empleando el método de los elementos discretos

  C. Recarey Morfa, E. Oñate, J. Canet, J. Rojek, F. Zarate, S. Burrel

  Ingeniería Civil (2006). Vol. 141, pp. 19-34

  
  

  Abstract

  Se presenta un modelo numérico que emplea elementos discretos esféricos o también denominados elementos distintos. Este modelo se aplica en la simulación de problemas de desgaste. El movimiento de elementos esféricos se describe por medio de las ecuaciones de Newton-Euler. Se emplea en la formulación una integración explícita, la cual, brinda una buena eficiencia computacional. Los elementos esféricos interactúan recíprocamente entre sí a través de las fuerzas de contacto. El esquema de búsqueda de contacto es muy eficaz, y está basado en las estructuras de oct-tree. El modelo constitutivo de contacto presenta una singularidad muy especial, ya que puede simular las fuerzas de cohesión que permiten modelar la fractura y descohesión de los materiales. El estudio de desgastes se realiza a partir de una formulación termo­acoplada que se aplica a nivel experimental, o escala reducida, y además in-situ o escala real.

  Abstract
  Se presenta un modelo numérico que emplea elementos discretos esféricos o también denominados elementos distintos. Este modelo se aplica en la simulación [...]

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• Posibilidades de los métodos numéricos en el mundo industrial

  E. Oñate

  Col·lecció Aula de Ciència i Cultura (2002). Nº 13, pp. 9-33

  
  

  Abstract

  Se presentan en el artículo las ideas básicas de qué son los métodos numéricos, cuáles son los métodos numéricos más populares, cómo se aplican para resolver ecuaciones diferenciales de interés práctico en ingeniería y qué posibilidades y limitaciones tienen para ayudarnos a entender mejor el mundo que nos rodea. El contenido del artículo se completa con diversas aplicaciones prácticas del método de elementos finitos a diversos problemas de ingeniería.

  Abstract
  Se presentan en el artículo las ideas básicas de qué son los métodos numéricos, cuáles son los métodos numéricos más [...]

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• A large strain plasticity model for anisotropic materials - composite material application

  E. Car, S. Oller, E. Oñate

  International Journal of Plasticity (2001). Vol. 17 (11), pp. 1437-1463

  
  

  Abstract

  In this work a generalized anisotropic model in large strains based on the classical isotropic plasticity theory is presented. The anisotropic theory is based on the concept of mapped tensors from the anisotropic real space to the isotropic fictitious one. In classical orthotropy theories it is necessary to use a special constitutive law for each material. The proposed theory is a generalization of classical theories and allows the use of models and algorithms developed for isotropic materials. It is based on establishing a one-to-one relationship between the behavior of an anisotropic real material and that of an isotropic fictitious one. Therefore, the problem is solved in the isotropic fictious space and the results are transported to the real field. This theory is applied to simulate the behavior of each material in the composite. The whole behavior of the composite is modeled by incorporating the anisotropic model within a model based on a modified mixing theory.

  Abstract
  In this work a generalized anisotropic model in large strains based on the classical isotropic plasticity theory is presented. The anisotropic theory is based on the concept [...]

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• Optimización de embarcaciones de recreo mediante la utilización de un código CFD

  M. López-Rodríguez, J. García-Espinosa, E. Oñate

  Ingeniería Naval (2001). Vol. 784, pp. 122-130

  
  

  Abstract

  En la actualidad las más avanzadas técnicas para diseño naval ya no se restringen sólo a proyectos de alto coste; si no que también ahora son de aplicación en el campo de las embarcaciones de recreo y turísticas, dando con ello un valor añadido al proyecto final. La utilización de un código CFD para el mayor conocimiento del comportamiento hidrodinámico de las embarcaciones de recreo y turísticas es de una gran utilidad debido a las complejidades que en el diseño de estas se presentan. Estas herramientas nos van a proporcionar una serie de datos como sustentación lateral en las embarcaciones de vela o interacción entre cascos en catamaranes con deriva lateral, que de otra forma nunca pudieran conocerse. Los resultados hidrodinámicos obtenidos nos sirven para comparar las diferentes alternativas, y para además obtener unos valores que directamente son usados para la predicción de velocidad de la embarcación, que más tarde se verán refrendadas por las pruebas de mar. La utilización de técnicas CFD, basadas en el método de los elementos finitos, para la resolución de las ecuaciones de Reynolds (RANSE), incluyendo efectos de superficie libre, hace que todo esto sea posible. En este trabajo se presentan diversos resultados de aplicación del código CFD SHYNE a varias embarcaciones deportivas y de recreo. SHYNE está basado en la técnica del Cálculo Finitesimal para la integración de las ecuaciones de Reynolds.

  Abstract
  En la actualidad las más avanzadas técnicas para diseño naval ya no se restringen sólo a proyectos de alto coste; si no que también ahora [...]

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• ED-Elas2D: An Educational Program for Computer-aided Training in Structural Analysis Using the Finite Element Method

  B. Suarez, E. Blanco, L. Gil, P. Zapata, E. Oñate

  European Journal of Engineering Education (1998). Vol. 23 (2), pp. 243-254

  
  

  Abstract

  In this paper, a methodology for computer-aided training of structural problems by the finite element method is presented. The resulting educational program, named ED-Elas2D, has been developed by a group of researchers at the School of Civil Engineering at the Technical University of Catalonia (UPC) in Barcelona, UPC. The program combines the standard concept which appears in the traditional teaching of finite element methods for structural analysis, such as the introduction to the basic structural theory, data definition (pre-processor), description of the analysis procedure (processor) and interpretation of results (post-processor). The program is addressed to both students who enrol in the study on finite element methods and to academic and technical staff in universities and companies who wish to update their knowledge of finite element techniques. The educational program ED-Elas2D works in the Windows system and it is characterized by its interactivity and graphic utilities.

  Abstract
  In this paper, a methodology for computer-aided training of structural problems by the finite element method is presented. The resulting educational program, named ED-Elas2D, [...]

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• A finite element model for thermomechanical analysis in casting processes

  D. Celentano, S. Oller, E. Oñate

  Journal of Physique IV (1993). Vol. 3 (C7), pp. 1171-1180

  
  

  Abstract

  This paper summarizes the recent work of the authors in the numerical simulation of casting processes. In particular, a coupled thermomechanical model to simulate the solidification problem in casting has been developed [7,8,9]. The model, based on a general isotropic thermoelasto-plasticity theory and formulated in a macroscopical point of view, includes generalized phase-change effects and considers the different thermomechanical behaviour of the solidifying material during its evolution from liquid to solid. For this purpose, a phase-change variable, plastic evolution equations and a temperature-dependent material constitutive law have been defined. Some relevant aspects of this model are presented here. Full thermomechanical coupling terms have been considered as well as variable thermal and mechanical boundary conditions : the first are due to air gap formation, while the second involve a contact formulation. Particular details concerning the numerical implementation of this model are also mentioned. An enhanced staggered scheme, used to solve the highly non-linear fully coupled finite element equations, is proposed. Furthermore, a proper convergence criterion to stop the iteration process is adopted and, although the quadratic convergence of Newton-Rapshon's method is not achieved, several numerical experiments demonstrate reasonable convergence rates [9]. Finally, an experimental cylindrical casting test problem, including phase-change phenomena, temperature-dependent constitutive properties and contact effects, is analyzed. Numerical results are compared with some laboratory measurements.

  Abstract
  This paper summarizes the recent work of the authors in the numerical simulation of casting processes. In particular, a coupled thermomechanical model to simulate the solidification [...]

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• Análisis no lineal de tanques criogénicos bajo cargas térmicas

  J. Oliver, E. Oñate, J. Peraire, R. Chueca

  Hormigón y Acero (1985). Vol. 155, pp. 99-123

  
  

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• La formulación del flujo viscoplástico y sus diversas aplicaciones prácticas por el método de los elementos finitos

  E. Oñate

  Revista de Obras Públicas (1980). Vol. 127 (3178), pp. 115-129

  
  

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Articles (Documents not available in Scipedia)

• Comparative study of different discrete element models and evaluation of equivalent micromechanical parameters

  J Rojek, C Labra, O Su, E Oñate

  International Journal of Solids and Structures 49 (13), 1497-1517, 2012

• A monolithic Lagrangian approach for fluid–structure interaction problems

  PB Ryzhakov, R Rossi, SR Idelsohn, E Oñate

  Computational mechanics 46 (6), 883-899, 2010

• Multi-fluid flows with the particle finite element method

  S Idelsohn, M Mier-Torrecilla, E Oñate

  Computer methods in applied mechanics and engineering 198 (33), 2750-2767, 2009

• High‐density sphere packing for discrete element method simulations

  C Labra, E Onate

  Communications in Numerical Methods in Engineering 25 (7), 837-849

• Modeling of ground excavation with the particle finite-element method

  JM Carbonell, E Oñate, B Suárez

  Journal of engineering mechanics 136 (4), 455-463, 2009

• Fluid–structure interaction problems with strong added‐mass effect

  SR Idelsohn, F Del Pin, R Rossi, E Oñate

  International journal for numerical methods in engineering 80 (10), 1261-1294, 2009

• Interaction between an elastic structure and free-surface flows: experimental versus numerical comparisons using the PFEM

  SR Idelsohn, J Marti, A Souto-Iglesias, E Onate

  Computational Mechanics 43 (1), 125-132, 2008

• Composite materials non-linear modelling for long fibre-reinforced laminates: Continuum basis, computational aspects and validations

  F Rastellini, S Oller, O Salomón, E Oñate

  Computers & Structures 86 (9), 879-896, 2008

• Validation of the particle finite element method (PFEM) for simulation of free surface flows

  A Larese, R Rossi, E Oñate, SR Idelsohn

  Engineering Computations 25 (4), 385-425, 2008

• Unified Lagrangian formulation for elastic solids and incompressible fluids: application to fluid–structure interaction problems via the PFEM

  SR Idelsohn, J Marti, A Limache, E Oñate

  Computer Methods in Applied Mechanics and Engineering 197 (19), 1762-1776, 2008

• Advances in the particle finite element method for the analysis of fluid–multibody interaction and bed erosion in free surface flows

  E Onate, SR Idelsohn, MA Celigueta, R Rossi

  Computer Methods in Applied Mechanics and Engineering 197 (19), 1777-1800, 2008

• Multiscale analysis using a coupled discrete/finite element model

  J Rojek, E Oñate

  Interaction and Multiscale Mechanics 1 (1), 1-31, 2007

• An improved finite point method for tridimensional potential flows

  E Ortega, E Oñate, S Idelsohn

  Computational Mechanics 40 (6), 949-963, 2007

• A rotation‐free shell triangle for the analysis of kinked and branching shells

  FG Flores, E Onate

  International Journal for Numerical Methods in Engineering 69 (7), 1521-1551, 2007

• Simulation of flows with violent free surface motion and moving objects using unstructured grids

  R Löhner, C Yang, E Oñate

  International Journal for Numerical Methods in Fluids 53 (8), 1315-1338, 2007

• The ALE/Lagrangian particle finite element method: a new approach to computation of free-surface flows and fluid–object interactions

  F Del Pin, S Idelsohn, E Oñate, R Aubry

  Computers & Fluids 36 (1), 27-38, 2007

• Modeling bed erosion in free surface flows by the particle finite element method

  E Oñate, MA Celigueta, SR Idelsohn

  Acta Geotechnica 1 (4), 237-252, 2006

• FIC/FEM formulation with matrix stabilizing terms for incompressible flows at low and high Reynolds numbers

  E Oñate, A Valls, J García

  Computational Mechanics 38 (4-5), 440-455, 2006

• Finite calculus formulations for finite element analysis of incompressible flows. Eulerian, ALE and Lagrangian approaches

  E Oñate, J García, SR Idelsohn, F Del Pin

  Computer methods in applied mechanics and engineering 195 (23), 3001-3037, 2006

• On the simulation of flows with violent free surface motion

  R Löhner, C Yang, E Oñate

  Computer Methods in Applied Mechanics and Engineering 195 (41), 5597-5620, 2006

• To mesh or not to mesh. That is the question…

  SR Idelsohn, E Onate

  Computer methods in applied mechanics and engineering 195 (37), 4681-4696, 2006

• Fluid–structure interaction using the particle finite element method

  SR Idelsohn, E Onate, F Del Pin, N Calvo

  Computer Methods in Applied Mechanics and Engineering 195 (17), 2100-2123, 2006

• Simple modifications for stabilization of the finite point method

  B Boroomand, AA Tabatabaei, E Onate

  International Journal for Numerical Methods in Engineering 63 (3), 351-379, 2005

• A continuum mechanics model for mechanical fatigue analysis

  S Oller, O Salomón, E Oñate

  Computational Materials Science 32 (2), 175-195, 2005

• Simulation of light‐weight membrane structures by wrinkling model

  R Rossi, M Lazzari, R Vitaliani, E Oñate

  International Journal for Numerical Methods in Engineering 62 (15), 2127-2153, 2005

• Improvements in the membrane behaviour of the three node rotation-free BST shell triangle using an assumed strain approach

  FG Flores, E Onate

  Computer Methods in Applied Mechanics and Engineering 194 (6), 907-932, 2005

• Particle finite element method in fluid-mechanics including thermal convection-diffusion

  R Aubry, SR Idelsohn, E Oñate

  Computers & structures 83 (17), 1459-1475, 2005

• Advances in the formulation of the rotation-free basic shell triangle

  E Oñate, FG Flores

  Computer methods in applied mechanics and engineering 194 (21), 2406-2443, 2005

• A general advancing front technique for filling space with arbitrary objects

  R Löhner, E Oñate

  International journal for numerical methods in engineering 61 (12), 1977-1991, 2004

• Finite calculus formulation for incompressible solids using linear triangles and tetrahedra

  E Oñate, J Rojek, RL Taylor, OC Zienkiewicz

  International Journal for Numerical Methods in Engineering 59 (11), 1473-1500, 2004

• Possibilities of finite calculus in computational mechanics

  E Oñate

  International journal for numerical methods in engineering 60 (1), 255-281, 2004

• Combination of discrete element and finite element methods for dynamic analysis of geomechanics problems

  E Onate, J Rojek

  Computer methods in applied mechanics and engineering 193 (27), 3087-3128, 2004

• The particle finite element method—an overview

  E Oñate, SR Idelsohn, F Del Pin, R Aubry

  International Journal of Computational Methods 1 (02), 267-307, 2004

• The particle finite element method: a powerful tool to solve incompressible flows with free‐surfaces and breaking waves

  SR Idelsohn, E Oñate, FD Pin

  International journal for numerical methods in engineering 61 (7), 964-989, 2004

• A residual correction method based on finite calculus

  E Oñate, RL Taylor, OC Zienkiewicz, J Rojek

  Engineering Computations 20 (5/6), 629-658, 2003

• The extended Delaunay tessellation

  N Calvo, SR Idelsohn, E Oñate

  Engineering Computations 20 (5/6), 583-600, 2003

• Polyhedrization of an arbitrary 3D point set

  SR Idelsohn, N Calvo, E Onate

  Computer Methods in Applied Mechanics and Engineering 192 (22), 2649-2667, 2003

• A Lagrangian meshless finite element method applied to fluid–structure interaction problems

  SR Idelsohn, E Onate, F Del Pin

  Computers & Structures 81 (8), 655-671, 2003

• The meshless finite element method

  SR Idelsohn, E Onate, N Calvo, F Del Pin

  International Journal for Numerical Methods in Engineering 58 (6), 893-912, 2003

• Numerical simulation of fiber reinforced composite materials––two procedures

  E Car, F Zalamea, S Oller, J Miquel, E Oñate

  International Journal of Solids and Structures 39 (7), 1967-1986, 2002

• A finite element methodology for local/global damage evaluation in civil engineering structures

  AD Hanganu, E Onate, AH Barbat

  Computers & Structures 80 (20), 1667-1687, 2002

• A finite point method for compressible flow

  R Löhner, C Sacco, E Onate, S Idelsohn

  International Journal for Numerical Methods in Engineering 53 (8), 1765-1779, 2002

• Lagrangian formulations to solve free surface incompressible inviscid fluid flows

  SR Idelsohn, MA Storti, E Oñate

  Computer Methods in Applied Mechanics and Engineering 191 (6), 583-593, 2001

• A large strain plasticity model for anisotropic materials—composite material application

  E Car, S Oller, E Oñate

  International Journal of Plasticity 17 (11), 1437-1463, 2001

• A basic thin shell triangle with only translational DOFs for large strain plasticity

  FG Flores, E Onate

  International Journal for numerical methods in engineering 51 (1), 57-83, 2001

• A finite element method for fluid–structure interaction with surface waves using a finite calculus formulation

  E Oñate, J Garcıa

  Computer methods in applied mechanics and engineering 191 (6), 635-660, 2001

• A finite point method for elasticity problems

  E Oñate, F Perazzo, J Miquel

  Computers & Structures 79 (22), 2151-2163, 2001

• Stabilization techniques for finite element analysis of convection-diffusion problems

  E Oñate, M Manzan

  Developments in Heat Transfer 7, 71-118, 2000

• An anisotropic elastoplastic constitutive model for large strain analysis of fiber reinforced composite materials

  E Car, S Oller, E Oñate

  Computer Methods in Applied Mechanics and Engineering 185 (2), 245-277, 2000

• A simple method for automatic update of finite element meshes

  G Chiandussi, G Bugeda, E Oñate

  Communications in Numerical Methods in Engineering 16 (1), 1-19, 2000

• A finite point method for incompressible flow problems

  E Oñate, C Sacco, S Idelsohn

  Computing and visualization in science 3 (1-2), 67-75, 2000

• Rotation-free triangular plate and shell elements

  E Onate, F Zarate

  International Journal for Numerical Methods in Engineering 47 (1-3), 557-603, 2000

• A stabilized finite element method for incompressible viscous flows using a finite increment calculus formulation

  E Onate

  Computer methods in applied mechanics and engineering 182 (3), 355-370, 2000

• A generalized streamline finite element approach for the analysis of incompressible flow problems including moving surfaces

  MA Cruchaga, E Oñate

  Computer Methods in Applied Mechanics and Engineering 173 (1), 241-255, 1999

• A general procedure for deriving stabilized space–time finite element methods for advective–diffusive problems

  E Oñate, M Manzan

  International Journal for Numerical Methods in Fluids 31 (1), 203-221, 1999

• A homogeneous constitutive model for masonry

  J Lopez, S Oller, E Onate, J Lubliner

  International journal for numerical methods in engineering 46 (10), 1651-1671, 1999

• Application of explicit FE codes to simulation of sheet and bulk metal forming processes

  J Rojek, E Onate, E Postek

  Journal of Materials Processing Technology 80, 620-627, 1998

• An advancing front point generation technique

  R Löhner, E Onate

  Communications in numerical methods in engineering 14 (12), 1097-1108, 1998

• A hierarchical finite element method based on the partition of unity

  RL Taylor, OC Zienkiewicz, E Oñate

  Computer Methods in Applied Mechanics and Engineering 152 (1), 73-84, 1998

• Experimental and numerical issues in the modelling of the mechanical behaviour of masonry

  P Roca, JL González, E Oñate, PB Lourenço

  Structural Analysis of Historical Constructions II. CIMNE, Barcelona, 1998

• A mesh-free finite point method for advective-diffusive transport and fluid flow problems

  E Onate, S Idelsohn

  Computational Mechanics 21 (4-5), 283-292, 1998

• Derivation of stabilized equations for numerical solution of advective-diffusive transport and fluid flow problems

  E Oñate

  Computer Methods in Applied Mechanics and Engineering 151 (1), 233-265, 1998

• A finite element formulation for incompressible flow problems using a generalized streamline operator

  MA Cruchaga, E Oñate

  Computer Methods in Applied Mechanics and Engineering 143 (1), 49-67, 1997

• Viscous damage model for Timoshenko beam structures

  AH Barbat, S Oller, E Oñate, A Hanganu

  International Journal of Solids and Structures 34 (30), 3953-3976, 1997

• A plastic damage constitutive model for composite materials

  S Oller, E Oñate, J Miquel, S Botello

  International journal of Solids and Structures 33 (17), 2501-2518, 1996

• An unstructured grid-based, parallel free surface solver

  R Löhner, C Yang, E Oñate, S Idelssohn

  Centro Internacional de Métodos Numéricos en Ingeniería, 1996

• A finite point method in computational mechanics. Applications to convective transport and fluid flow

  E Onate, S Idelsohn, OC Zienkiewicz, RL Taylor

  International journal for numerical methods in engineering 39 (22), 3839-3866, 1996

• A stabilized finite point method for analysis of fluid mechanics problems

  E Onate, S Idelsohn, OC Zienkiewicz, RL Taylor, C Sacco

  Computer Methods in Applied Mechanics and Engineering 139 (1), 315-346, 1996

• Moving least square approximations for solution of differential equations

  RL Taylor, OC Zienkiewicz, E Oñate, S Idelsohn

  Centro Internacional de Métodos Numéricos en Ingeniería, 1995

• Cálculo de estructuras por el método de elementos finitos: análisis elástico lineal

  E Oñate

  Centro Internacional de Métodos Numéricos en Ingeniería, 1992

• Plastic Flow in Metal Forming. I.--Coupled Thermal. II.--Thin Sheet Forming

  DC Zienkiewicz, E Onate, JC Heinrich

  Applications of Numerical Methods to Forming Processes, 107-120, 1978