Documents published in 2019 : Scipedia

A new frictional time integration algorithm for large slip multi-body frictional contact problems
C. Agelet de Saracibar

(1995). Research Report, Nº PI69

Abstract
In this paper a new frictional time integration algorithm suitable for large slip multibody frictional contact problems is presented. The algorithm is introduced within the simple context of a model problem: the sliding motion of a particle onto a rough surface. Time integration of frictional traction is performed introducing a new slip path parametrization, which is defined independently traction is performed introducing element parametrization used in the spatial triangularization. The key point of the algorithm is that now, in presence of large slips, problems associated with slip motions such that a full incremental slip path is not within a single surface element, are completed bypassed. Remarkably, the algorithm is defined on the solely basis of the unit outward normal field to the surface without any appeal to the underlying local surface finite element triangularization. Geometrically, the assumed slip path can be viewed as an approximation to the geodesic passing throughout the initial and final points of each incremental slip path. The algorithm is amenable to exact linearization and asymptotic quadratic rate of convergence can be achieved within a Newton-Raphson iterative solution scheme. The algorithm can easily be extended to large slip multi-body frictional contact problems, involving finite strains.
Abstract
In this paper a new frictional time integration algorithm suitable for large slip multibody frictional contact problems is presented. The algorithm is introduced within the [...]
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numerical analysis of frictional wear contact problems computational model and applications
C. Agelet de Saracibar, M. Chiumenti

(1995). Research Report, Nº PI70

Abstract
In this paper a numerical model for the analysis of multi-body frictional wear contact problems at finite deformations is presented. Wear phenomena are analysed and the main wear mechanics are identified. Archard’s wear law provides an estimate of the amount of wear volume produced during forming operations. Wear phenomena are incorporated into the Coulomb frictional model by considering a friction coefficient as function of an internal variable to be defined as the frictional dissipation or the slip amount. Within the context of a displacement-driven formulation of frictional contact problems, i.e. penalty or augmented Lagrangian methods, and exploiting the computational framework developed for plasticity, two methods are considered for the time integration of the constrained frictional evolution problems: the lowest Backward Difference (BD) method, Backward Euler (BE) algorithm, and an Implicit Runge-Kutta (IRK) method, the generalized Projected Mid-Point (PMP) algorithm. The constrained frictional algebraic problem arising from the application of these time integration algorithms to the constrained frictional evolution problem, is amenable to exact linearization leading to an asymptotic quadratic rate of convergence when used within a Newton-Raphson solution scheme. The numerical model has been implemented into an enhanced version of the computational finite element program FEAP. Numerical examples and simulation of industrial metal forming processes show the performance of the numerical model in the analysis of frictional wear contact problems.
Abstract
In this paper a numerical model for the analysis of multi-body frictional wear contact problems at finite deformations is presented. Wear phenomena are analysed and the main [...]
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Simulación del choque de vehículos por el método de los elementos finitos. Programa "SIMPACT"
J. Rojek, E. Oñate, J. Canet

(1995). Research Report, Nº PI71

Abstract
En este trabajo se presentan las principales características del programa de ordenador “SIMPACT” desarrollado en el Centro Internacional de Métodos Numéricos en Ingeniería de Barcelona para la simulación numérica de problemas de impacto y choque de vehículos. El programa se basa en una formulación de elementos finitos de lámina no lineal incorporando también elementos de sólido y de viga para modelar correctamente todos los componentes resistente típicos de estructuras de vehículos. El programa permite la utilización de algoritmos de integración en el tiempo explícitos incluyendo además modelos constitutivos para materiales compuestos. Los ejemplos que se presentan muestran la aplicación del programa a la deformación de una puerta sometida a un ensayo penetración lateral, el choque frontal de un prototipo de vehículo industrial, y el vuelco de una cabina de autobús.
Abstract
En este trabajo se presentan las principales características del programa de ordenador “SIMPACT” desarrollado en el Centro Internacional de Métodos [...]
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Análisis de procesos de conformado de metales por el método de los elementos finitos. Posibilidades y perspectivas.
E. Oñate

(1995). Research Report, Nº PI72
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Structural analysis and durability assessment of historical construction using a finite element damage model
E. Oñate, A. Hanganu, A. Barbat, S. Oller, R. Vitaliani, A. Saetta, R. Scotta

(1995). Research Report, Nº PI73
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Moving least square approximations for solution of differential equations
R. Taylor, O. Zienkiewicz, E. Oñate

(1995). Research Report, Nº PI74
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A rate-dependent isotropic damage model for the seismic analysis of concrete dams
M. Cervera, J. Oliver, O. Manzoli

(1995). Research Report, Nº PI76

Abstract
In this paper a rate‐dependent isotropic damage model developed for the numerical analysis of concrete dams subjected to seismic excitation is presented. The model is shown to incorporate two features essential for seismic analysis: stiffness degradation and stiffness recovery upon load reversals and strain‐rate sensitivity. The issue of mesh objectivity is addressed using the concept of the ‘characteristic length’ of the fracture zone, to show that both the softening modulus and the fluidity parameter must depend on it to provide consistent results as the computational mesh is refined. Some aspects of the numerical implementation of the model are also treated, to show that the model can be easily incorporated in any standard non‐linear finite element code. The application of the proposed model to the seismic analysis of a large gravity concrete dam shows that the structural response may vary significantly in terms of the development of damage. The inclusion of rate sensitivity is able to reproduce the experimental observation that the tensile peak strength of concrete can be increased up to 50 percent for the range of strain rates that appear in a structural safety analysis of a dam subjected to severe seismic actions.
Abstract
In this paper a rate‐dependent isotropic damage model developed for the numerical analysis of concrete dams subjected to seismic excitation is presented. The model is shown [...]
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Viscous damage model for Timoshenko beam structures
A. Barbat, S. Oller, E. Oñate, A. Hanganu

(1995). Research Report, Nº PI77

Abstract
A local damage constitutive model based on Kachanov’s theory is used within a finite element frame and applied to the case of 2D and 3D Timoshenko beam elements. The model takes into account viscous effects, thus allowing damping to be considered in a rigorous way. A damage index based on potential energy criteria, useful in evaluating the behaviour of structures or of parts of structures, is proposed. The procedure is applied to estimate the damage produced by seismic actions in reinforced concrete building structures, whose response is computed by using a non-linear Newmark-type incremental time integration scheme. Three numerical examples are included; one of them compares results obtained by using the proposed model with results of a laboratory test.
Abstract
A local damage constitutive model based on Kachanov’s theory is used within a finite element frame and applied to the case of 2D and 3D Timoshenko beam elements. The [...]
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Alguns aspectos da simulação numérica pelo método dos elementos finitos da estampagem de chapas finas
E. Casas

(1995). Research Report, Nº PI78
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The energy input spectrum scaling laws and synthetic compatible records
J. Hurtado, A. Barbat

(1995). Research Report, Nº PI79

Abstract
A method for predicting the seismic energy input spectrum is presented. The method is based on the analytical relationship linking this spectrum and other measures of earthquake energy such as power spectrum and Arias intensity, and the results of the statistical analysis made on 120 strong motion records. Upon the same relationships, a method for simulating artificial accelerograms compatible with a prescribed energy input spectrum is also developed. This procedure is used for the calculation of damage indexes for reinforced concrete single-degree-of freedom-systems, corresponding to types of energy input spectra and different ground motion durations.
Abstract
A method for predicting the seismic energy input spectrum is presented. The method is based on the analytical relationship linking this spectrum and other measures of earthquake [...]
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On the stabilization of numerical solution for advective-diffusive transport and fluid flow problems
E. Oñate

(1996). Research Report, Nº PI81

Abstract
The concept of the so called “artificial or balancing diffusion” used to stabilize the numerical solution of advective diffusive transport and fluid flow problems is revised in this paper. It is shown that the standard forms of the balancing diffusion terms, usually chosen in a heuristic manner, can be naturally found by introducing higher order approximations in the derivation of the governing differential equations via standard conservation (or equilibrium) principles. This allows us to reinterprete many stabilization algorithms and concepts used in every day practice by numerical analysts and also provides an expression for computing the stabilization parameter.
Abstract
The concept of the so called “artificial or balancing diffusion” used to stabilize the numerical solution of advective diffusive transport and fluid flow [...]
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comparing two algorithms to add large strains to a small strain finite element code
A. Rodríguez-Ferran, A. Huerta

(1996). Research Report, Nº PI91

Abstract
Two algorithms for the stress update (i.e., time-integration of the constitutive equation) in large strain solid mechanics are discussed, with particular emphasis on two issues: the incremental objectivity and the implementation aspects. It is shown that both algorithms are incrementally objective (i.e., they treat rigid rotations properly) and that they can be employed to add large strain capabilities to a small large deformation paths (rigid rotation, simple shear, extension, extension and compression, dilatation, extension and rotation), have been used to test and compare the two algorithms, both for elastic and plastic analysis. These test evidence different time integration accuracy for each algorithm. However, it is demonstrated that the, in general, less accurate algorithm gives exact results for shear-free deformation paths.
Abstract
Two algorithms for the stress update (i.e., time-integration of the constitutive equation) in large strain solid mechanics are discussed, with particular emphasis on two issues: [...]
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comparison of some finite element methods for solving the diffusion-convection-reaction equation
R. Codina

(1996). Research Report, Nº PI101

Abstract
In this paper we describe several finite element methods for solving the diffusion-convection-reaction equation. None of them is new, although the presentation is non-standard in an effort to emphasize the similarities and differences between them. In particular, it is shown that the classical SUPG method is very similar to an explicit version of the Characteristic-Galerkin method, whereas the Taylor-Galerkin method has a stabilization effect similar to a sub-grid scale model, which is un turn related to the introduction of bubbles functions.
Abstract
In this paper we describe several finite element methods for solving the diffusion-convection-reaction equation. None of them is new, although the presentation is non-standard [...]
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A fractional step method for the solution of the compressible Navier-Stokes equations
R. Codina, M. Vázquez, O. Zienkiewicz

(1997). Research Report, Nº PI118

Abstract
In this paper we present a summary of the splitting technique for both compressible and incompressible flows previously proposed in [22, 23, 7]. Also, we extend it to the case of a fully implicit treatment of the viscous and convective terms of the momentum equations. For incompressible flows, this scheme for a non-standard treatment of the boundary conditions. For compressible flows the continuity equation involves two variables which must be related through the equation of state. Convective terms of the conservation equations to be solved are stabilized by means of a Characteristic – Galerkin scheme. Also, in the presence of shocks some additional dissipation is needed. Both numerical techniques are explained here taking the transport of a scalar quantity as a model problem.
Abstract
In this paper we present a summary of the splitting technique for both compressible and incompressible flows previously proposed in [22, 23, 7]. Also, we extend it to the [...]
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On stabilized finite element methods for linear systems of convection-diffusion-reaction equations
R. Codina

(1997). Research Report, Nº PI126

Abstract
A stabilized finite element method for solving systems of convection-diffusion-reaction equations is studied in this paper. The method is based on the subgrid scale approach and an algebraic approximation to the subscales. After presenting the formulation of the method, it is analyzed how it behaves under changes of variables, showing that it relies on the law of change of the matrix of stabilization parameters associated to the method. An expression for this matrix is proposed for the case of general coupled systems of equations that is an extension of the expression proposed for a 1D model problem. Applications of the stabilization technique to the Stokes problem with convection and to the bending of Reissner-Mindlin plates are discussed next. The design of the matrix of stabilization parameters is based on the identification of the stability deficiencies of the standard Galerkin method applied to these two problems.
Abstract
A stabilized finite element method for solving systems of convection-diffusion-reaction equations is studied in this paper. The method is based on the subgrid scale approach [...]
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Error estimation including pollution assesment for nonlinear finite element analysis
A. Huerta, P. Díez

(1998). Research Report, Nº PI132

Abstract
The present paper proposes a new technique for the definition of the shape design variables in 2D and 3D optimisation problems. It can be applied to the discrete model of the analysed structure or to the original geometry without any previous knowledge of the analytical expression of the CAD defining surfaces. The proposed technique allows the surface continuity to be preserved during the geometry modification process to be defined a priori. This capability allows for the definition of shape variables suitable for every kind of discipline involved in the optimisation process (structural analysis, fluid-dynamic analysis, crash analysis, aerodynamic analysis, etc.).
Abstract
The present paper proposes a new technique for the definition of the shape design variables in 2D and 3D optimisation problems. It can be applied to the discrete model of [...]
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High-order accuarte time-stepping schemes for convection-diffusion problems
J. Donea, B. Roig, A. Huerta

(1998). Research Report, Nº PI135

Abstract
A major objective of the study described in the present paper is to achieve a high accuracy in the time integration of transient convection-diffusion problems and to eventually combine this with new methods for space discretization, such as meshless methods. In this way, a uniformly high-order accurate methodology could be made available for the numerical solution of convection-diffusion problems. Both Padé approximations of the exponential function and Runge-Kutta methods are considered for deriving multi-stage schemes involving first time derivatives only, thus easier to implement than standard Taylor-Galerkin schemes which incorporate second and third time derivatives. After a brief discussion of the stability and accuracy properties of the stability and accuracy properties of the multi-stage schemes and the presentation of illustrative examples, the paper closes with some considerations on the coupling of high-order accurate temporal schemes and meshless methods for the spatial representation.
Abstract
A major objective of the study described in the present paper is to achieve a high accuracy in the time integration of transient convection-diffusion problems and to eventually [...]
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Adaptive finite element strategies based on error assessment
A. Huerta, A. Rodríguez-Ferran, P. Díez

(1998). Research Report, Nº PI136

Abstract
Two main ingredients are needed for adaptive finite element computations. First, the error of a given solution must be assessed, by means of either error estimators or errors indicators. After that, a new spatial discretization must be defined via h, p or r-adaptivity. In principle, any of the approaches for error assessment may be combined with any of the procedures for adapting the discretization. However, some combinations are elearly preferable. The advantages and limitations of the various alternatives are discussed. The most adequate strategies are illustrated by means of several applications in solid mechanics.
Abstract
Two main ingredients are needed for adaptive finite element computations. First, the error of a given solution must be assessed, by means of either error estimators or errors [...]
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Arbitrary Lagrangian-Eulerian formulation for fluid-rigid body interaction
J. Sarrate, A. Huerta, J. Donea

(1998). Research Report, Nº PI137

Abstract
A new formulation for two-dimensional fluid-rigid body interaction problems is developed. In particular, vortex-induced oscillations of a rigid boy in viscous incompressible flow are studied. The incompressible Naiver-Stokes equations are used to describe the motion of the fluid, while it is assumed that the rigid body is mounted on a system consisting of a spring and a dashpot. An arbitrary Lagrangian-Eulerian formulation (ALE) is used in order to account for large boundary motion. A general formulation for coupled problem is obtained by uncoupling the translation motion of the body from its rotational motion and developing a specific algorithm to efficiently handle the nonlinear dependence of the rotations. This general formulation ca be easily applied to multi-body problems. Two numerical examples involving either translations and rotations are presented as an illustration of the proposed methodologies for fluid-rigid body interaction.
Abstract
A new formulation for two-dimensional fluid-rigid body interaction problems is developed. In particular, vortex-induced oscillations of a rigid boy in viscous incompressible [...]
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Modelo constitutivo elastoplástico anisótropo en deformaciones finitas para análisis de materiales compuestos reforzados con fibras
E. Car, S. Oller, E. Oñate

(1998). Research Report, Nº PI139

Abstract
En este trabajo se presenta un modelo constitutivo elastoplástico anisótropo generalizado en deformaciones finitas para el análisis de materiales compuestos multifase utilizando el método de los elementos finitos. En la modelización del material compuesto se utiliza la teoría de mezclas en la cual se inserta el modelo constitutivo elastoplástico propuesto. El comportamiento elástico de un sólido anisótropo se simula con la teoría de la elasticidad clásica, mientras que el comportamiento no proporcional de un sólido anisótropo se simula mediante un modelo elastroplástico anisótropo en régimen de grandes deformaciones basado en una formulación isótropa equivalente. Este modelo asume la existencia de un espacio real anisótropo y de un espacio ficticio isótropo, en el cual se resuelve un problema ficticio. Ambos espacios están relacionados a través de una transformación lineal utilizando un tensor de cuarto orden que contiene la información del material real. Por último se presenta los detalles de la implementación numérica del modelo propuesto en un código de elementos finitos y ejemplos de aplicación del modelo al análisis del comportamiento lineal y no-lineal de materiales compuestos.
Abstract
En este trabajo se presenta un modelo constitutivo elastoplástico anisótropo generalizado en deformaciones finitas para el análisis de materiales compuestos [...]
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El proyecto "BAJEL". Una herramienta de diseño hidrodinámico de buques de pasaje
J. García-Espinosa, L. Rojas, J. Cabezas, J. Alonso

(1998). Research Report, Nº PI140

Abstract
El proyecto BAJEL consiste en la validación y desarrollo final de un sistema informático integral para ayudar al diseño hidrodinámico de buques. Tiene como objetivo contribuir al diseño óptimo de las nuevas generaciones de barcos, entre los que se encuentran los de pasaje, mejorando sus condiciones de navegación. Este proyecto se desarrolla como fruto de la labor conjunta de un Centro de Cálculo Numérico (CIMNE) y dos Centros de Investigación Hidrodinámica (ETSIN y Canal de El Pardo) en el marco de la realidad industrial representado por la Empresa Nacional BAZÁN. Este trabajo presenta los objetivos del Proyecto, describiendo las herramientas informáticas que han servido de base y punto de arranque del mismo. También se presenta los logros que en este campo han conseguido en los últimos años los equipos investigadores integrantes. Finalmente, se incluyen diferentes resultados de estudios llevados a cabo sobre geometrías reales de buques con especial dedicación a los buques de pasaje de alta velocidad.
Abstract
El proyecto BAJEL consiste en la validación y desarrollo final de un sistema informático integral para ayudar al diseño hidrodinámico de buques. [...]
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Estudio comparativo de métodos numéricos para resolver ecuaciones en derivadas parciales lineales
D. Vives

(1998). Research Report, Nº PI141

Abstract
La principal ventaja del método de los elementos finitos y del método de los volúmenes finitos es la capacidad que tienen de tratar con dominios ciertamente complejos de manera simple dándole un carácter local a la aproximación. Estos métodos dividen el dominio en un número finito de subdominios, que cumplen unas condiciones geométricas regulares. Para el caso 2-dimensional, ambos métodos no presentan grandes dificultades para la generación de una malla, mientras que en el caso 3-dimensional ello resulta bastante complicado y es uno de los problemas que actualmente se están estudiando con mayor profundidad, ya que, en la mayoría de los casos, la creación de una malla resulta computacionalmente más caro que la resolución numérica del problema. Principalmente por este motivo, se empezaron a estudiar los denominados métodos sin malla. Los primeros métodos se basaron es un intento de generalizar el método de las diferencias finitas a mallas irregulares. Otro de los primeros métodos estudiados son los denominados Smooth Particle Hydrodynamics (SPH). Estos métodos trabajan la ausencia de contornos, aunque no son tan precisos, como los métodos de elementos finitos regulares. Esta clase de métodos suele utilizarse frecuentemente para modelar fenómenos astrofísicos que no posean contornos. Recientemente, se han estudiado una clase de métodos, donde no es necesaria la creación de una malla. Los principios métodos son el método de los elementos difusos (DE), cuyo principal precursor fue Nayroles y el método Element-Free Galerkin (EFG). Ambos se basan en que las funciones interpolatorias son polinomios que tratan de aproximar la función en los nodos por un método de aproximación por mínimos cuadrados. En los dos casos no basta para formular las ecuaciones de Galerkin con una colección de nodos y una descripción del contorno. La diferencia entre ambos métodos radica es que en los métodos de los elementos difusos no se consideran necesarios. Los dos métodos son consistentes y bastante estables, aunque sustancialmente más caros que los métodos SPH. Gracias a un estudio de Duarte y Oden y a otro de Babuska y Melenk se han comprendido con mayor profundidad, y dicen que son métodos basados en la partición de la unidad. Estos personajes junto con Liu fueron los primeros en probar la convergencia de estos dos métodos. Finalmente, para concluir, hay que destacar la presencia de otra clase de métodos denominados Reproducing Kernel Particle (RKP), cuyo principal precursor fue Liu. En la sección 2, veremos una introducción teórica a algunos métodos como son elementos finitos, el método de los elementos difusos, el método EFG, los métodos SPH y finalmente el método de las diferencias finitas para el caso bidimensional. En la sección 3, abordaremos algunos aspectos sobre la programación de ellos, que ha sido efectuada, en el caso 1-dimensional, donde se han programada todos los anteriormente citados, salvo los SPH. La sección 4, contendrá breves remarcar sobre la programación de los métodos en el caso 2-dimensional, donde se han implementado los mismos métodos que en el caso 1-dimensional, con la excepción única de reemplazar el método de los elementos finitos por el de las diferencias finitas. La sección 5 y 6 se comentarán los resultados obtenidos para el caso 1-dimensional y 2-dimensional respectivamente. La seccón 7 contendrá algunas conclusiones y comentarios sobre el estudio.
Abstract
La principal ventaja del método de los elementos finitos y del método de los volúmenes finitos es la capacidad que tienen de tratar con dominios ciertamente [...]
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A viscoplastic model including non-linear isotropic and kinematic hardening
M. Chiumenti, C. Agelet de Saracibar, M. Cervera

(1998). Research Report, Nº PI143

Abstract
In this work the formulation of a general elasto-viscoplastic constitutive model is consistently derived within a thermodynamic framework. The constitutive behavior has been by a elasto-plastic free energy function. Plastic response has been modeled considering a J2 viscoplastic constitutive model, including non-linear isotropic and kinematic hardening. Time integration and linearization of the constitutive model is also introduced. Finally, a number of numerical tests will show the mechanical response of a specimen submitted to a loading-unloading cycle.
Abstract
In this work the formulation of a general elasto-viscoplastic constitutive model is consistently derived within a thermodynamic framework. The constitutive behavior has been [...]
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Numerical differentiation for local and global tangent operators in computational plasticity
G. Chiandussi, G. Bugeda, E. Oñate

(1998). Research Report, Nº PI144

Abstract
A simple method to automatically update the finite element mesh of the analysis domain is proposed. The method considers the mesh as a fictitious elastic body subjected to prescribed displacements at selected boundary points. The mechanical properties of each mesh element are appropriately selected in order to minimize the deformation and the distortion of the mesh elements. Different selection strategies have been used and compared in their application to simple examples. The method avoids the use of remeshing in the solution of shape optimization problems and reduces the number of remeshing steps in the solution of coupled fluid–structure interaction problems.
Abstract
A simple method to automatically update the finite element mesh of the analysis domain is proposed. The method considers the mesh as a fictitious elastic body subjected to [...]
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Thermo-chemo-mechanical model for concrete. I: Hydration and aging
M. Cervera, J. Oliver, T. Prato

(1998). Research Report, Nº PI146

Abstract
In this work a coupled thermo-chemo-mechanical model for the behavior of concrete at early ages is proposed. The model allows simulation of the observed phenomena of hydration, aging, damage, and creep. It is formulated within an appropriate thermodynamic framework, from which the state equations are derived. In this first part, the formulation and assessment of the thermochemical aspects of the model are presented. It is based on the reactive porous media theory, and it can accurately predict the evolution in time of the hydration degree and the hydration heat production. The evolution of the compressive and tensile strengths and elastic moduli is related to the aging degree, a concept introduced to account for the effect of the curing temperature in the evolution of the mechanical properties. The short- and long-term mechanical behavior is modeled by means of a viscoelastic damage model that accounts for the aging effects. The formulation and assessment of the mechanical part of the model are relegated to a companion paper.
Abstract
In this work a coupled thermo-chemo-mechanical model for the behavior of concrete at early ages is proposed. The model allows simulation of the observed phenomena of hydration, [...]
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A simple method for automatic update of finite element meshes
G. Chiandussi, G. Bugeda, E. Oñate

(1998). Research Report, Nº PI147

Abstract
A simple method to automatically update the finite element mesh of the analysis domain is proposed. The method considers the mesh as a fictitious elastic body subjected to prescribed displacements at selected boundary points. The mechanical properties of each mesh element are appropriately selected in order to minimize the deformation and the distortion of the mesh elements. Different selection strategies have been used and compared in their application to simple examples. The method avoids the use of remeshing in the solution of shape optimization problems and reduces the number of remeshing steps in the solution of coupled fluid–structure interaction problems
Abstract
A simple method to automatically update the finite element mesh of the analysis domain is proposed. The method considers the mesh as a fictitious elastic body subjected to [...]
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A stabilized finite element method for generalized stationary incompressible flows
R. Codina

(1999). Research Report, Nº PI148

Abstract
In this paper we describe a finite element formulation for the numerical solution of the stationary Navier-Stokes equations including Coriolis forces and the permeability of the medium. The stabilized method is based on the algebraic version of the sub-grid scale approach. We first describe this technique for general systems of convection-diffusion-reaction equations and then we apply it to linearized flow equations. The important point is the design of the matrix of stabilization parameters that the method has. This design is based on the identification of the stability problems of the Galerkin method and a scaling of variables argument to determine which coefficients must be included in the stabilization matrix. This, together with the convergence analysis of the linearized problem, leads to a simple expression for the stabilization parameters in the general situation considered in the paper. The numerical analysis of the linearized problem also shows that the method has optimal convergence properties.
Abstract
In this paper we describe a finite element formulation for the numerical solution of the stationary Navier-Stokes equations including Coriolis forces and the permeability [...]
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Rotation‐free triangular plate and shell elements
E. Oñate, F. Zárate

(1999). Research Report, Nº PI149

Abstract
The paper describes how the finite element method and the finite volume method can be successfully combined to derive two new families of thin plate and shell triangles with translational degrees of freedom as the only nodal variables. The simplest elements of the two families based on combining a linear interpolation of displacements with cell centred and cell vertex finite volume schemes are presented in detail. Examples of the good performance of the new rotation‐free plate and shell triangles are given.
Abstract
The paper describes how the finite element method and the finite volume method can be successfully combined to derive two new families of thin plate and shell triangles with [...]
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A stabilized finite element method for incompressible viscous flows using a finite increment calculus formulation
E. Oñate

(1999). Research Report, Nº PI150

Abstract
A stabilized finite element formulation for incompressible viscous flows is derived. The starting point are the modified Navier-Stokes equations incorporating naturally the necessary stabilization terms via a finite increment calculus (FIC) procedure. Application of the standard finite element Galerkin method to the modified differential equations leads to a stabilized discrete system of equations overcoming the numerical instabilities emanating from the advective terms and those due to the lack of compatibility between approximate velocity and pressure fields. The FIC method also provides a natural explanation for the stabilization terms appearing in all equations for both the Navier-Stokes and the simpler Stokes equations. Transient solution schemes with enhanced stabilization properties are also proposed. Finally a procedure for computing the stabilization parameters is presented.
Abstract
A stabilized finite element formulation for incompressible viscous flows is derived. The starting point are the modified Navier-Stokes equations incorporating naturally the [...]
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Numerical differentiation for Non-Trivial consistent tangent matrices: An application to the MRS-Lade model
A. Pérez-Foguet, A. Rodríguez-Ferran, A. Huerta

(1999). Research Report, Nº PI151

Abstract
In Reference the authors have shown that numerical differentiation is a competitive alternative to analytical derivatives for the computation of consistent tangent matrices. Relatively simple models were treated in that reference. The approach is extended here to a complex model: the MRS-Lade model. This plastic model has a cone-cap yield surface and exhibits strong coupling between the flow vector and the hardening moduli. Because of this, derivating these quantities with respect to stresses and internal variables –crucial step in obtaining consistent tangent matrices- is rather involved. Numerical differentiation is used here to approximate these derivatives. The approximated derivatives are then used 1) to compute consistent tangent matrices (global problem) and 2) to integrate the constitutive equation at each Gauss point (local problem) with the Newton-Raphson method. The choice of the stepsize (i.e. the perturbation in the approximation schemes), based on the concept of relative stepsize, poses no difficulties. In contrast to previous approaches the global problems. The computational efficiency (CPU time) and robustness of the proposed approach is illustrated by means of several numerical examples, where the major relevant topics are discussed in details.
Abstract
In Reference the authors have shown that numerical differentiation is a competitive alternative to analytical derivatives for the computation of consistent tangent matrices. [...]
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Thermo‐mechanical analysis of industrial solidification processes
M. Cervera, C. Agelet de Saracibar, M. Chiumenti

(1999). Research Report, Nº PI153

Abstract
The paper presents an up‐to‐date finite element numerical model for fully coupled thermo‐mechanical problems, focussing in the simulation of solidification processes of industrial metal parts. The proposed constitutive model is defined by a thermo‐visco‐elasto‐(visco)plastic free energy function which includes a contribution for thermal multiphase changes. Mechanical and thermal properties are assumed to be temperature‐dependent, and viscous‐like strains are introduced to account for the variation of the elastic moduli during the cooling process. The continuous transition between the initial fluid‐like and the final solid‐like behaviour of the part is modelled by considering separate viscous and elasto‐plastic responses as a function of the solid fraction. Thermo‐mechanical contact conditions between the mould and the part are specifically considered, assuming that the heat flux is a function of the normal pressure and the thermal and mechanical gaps. A fractional step method arising from an operator split of the governing equations is used to solve the non‐linear coupled system of equations, leading to a staggered product formula solution algorithm suitable for large‐scale computations. Representative simulations of industrial solidification processes are shown, and comparison of computed results using the proposed model with available experimental data is given.
Abstract
The paper presents an up‐to‐date finite element numerical model for fully coupled thermo‐mechanical problems, focussing in the simulation of solidification processes [...]
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New degrees of freedom in computational mechanics: mesh free finite point method, rotation free shell triangles and moving free meshes
E. Oñate

(1999). Research Report, Nº PI154

Abstract
The paper presents an overview of some recent developments in computational mechanics introducing new degrees of “freedom” allowing the solution of more challenging problems. First advances in the finite point method for fully mesh free solution in fluid and solid mechanics are described. Next, new rotation free shell triangles incorporating membrane and bending effects are presented. Finally, a simple method allowing free movement of meshes is described. Examples of application of all the “free” methods are given.
Abstract
The paper presents an overview of some recent developments in computational mechanics introducing new degrees of “freedom” allowing the solution of more challenging [...]
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A nodal-based implementation of a stabilized Finite Element Method for Incompressible Flow Problems
R. Codina

(1999). Research Report, Nº PI156

Abstract
The objective of this paper is twofold. First, a stabilized finite element method for the incompressible Navier-Stokes is presented, and several numerical experiments are conducted to check its performance. This method is able to deal with all the instabilities that the standard Galerkin method presents, namely, the pressure instability, the instability arising in convection dominated situations and also the less popular instabilities found when the Navier-Stokes equations have a dominant Coriolis force, or there is a dominant absorption term arising from the small permeability of the medium where the flow takes place. The second objective is to describe a nodal-based implementation of the finite element formulation introduced. This implementation is based on an a priori calculation of the integrals appearing in the formulation and then the construction of the matrix approximations, this matrix and this vector can be constructed directly for each nodal point, without the need to loop over element and thus making the calculations much faster. In order to be able to do this, all the variables have to be defined at the nodes of the finite element mesh, not on the elements. This is also so for the stabilization parameters of the formulation. However, doing this given rise to questions regarding the consistency and the conservation properties of the final scheme that are addressed in this paper.
Abstract
The objective of this paper is twofold. First, a stabilized finite element method for the incompressible Navier-Stokes is presented, and several numerical experiments are [...]
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Simulation of Construction of RCC Dams. I: Temperature and Aging
M. Cervera, J. Oliver, T. Prato

(1999). Research Report, Nº PI157

Abstract
In this work a numerical procedure for the simulation of the construction process of Roller Compacted Concrete (RCC) dams is described. The basis of the work is a coupled thermos-chemo-mechanical model for the behaviour of concrete at early ages that allows to simulate the observed phenomena of hydration, aging, creep and damage. In this first part only the thermochemical aspects of the simulation of the construction process are presented. The proposed procedure can accurately predict the evolution in time of the hydration degree and the hydration heat production. This allows to obtain the temperature field inside the dam at any time during the construction and the following years. The evolution of the compressive and tensile strengths and elastic moduli can also be predicted in terms of the evolutions of the hydration degree and the temperature conditions. Results from 2d and simplified vertical 1D models are compared and several parametric studies are carried out. The simulation and discussion of the mechanical aspects of the construction process are relegated to a companion paper that follows.
Abstract
In this work a numerical procedure for the simulation of the construction process of Roller Compacted Concrete (RCC) dams is described. The basis of the work is a coupled [...]
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BLAY3D: 3D boundary layer code. User's guide.
M. Storti

(1999). Research Report, Nº PI158

Abstract
This is the user’s guide for the BLAY3D code (version 2.2 of December 28, 1998). BLAY3D is a fluid mechanics code for solving the incompressible Boundary Layer Equations (BLE), based on a spectral approximation in the transversal direction and a mesh-less approximation on the surface of the body. It contains a basic description of what are the BLE, the governing equations involved, how they are solved, which is the data and how is it entered in order to be processed by BLAY3D, what kind of result BLAY3D generates, and finally several examples are shown.
Abstract
This is the user’s guide for the BLAY3D code (version 2.2 of December 28, 1998). BLAY3D is a fluid mechanics code for solving the incompressible Boundary Layer Equations [...]
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Transferencia de calor por conducción. Verificación del programa ED-Poiss
S. Robles, F. Zárate

(1999). Research Report, Nº PI161
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Stabilization of incompressibility and convection through orthogonal sub-scale in finite element methods
R. Codina

(1999). Research Report, Nº PI162

Abstract
Two apparently different forms of dealing with the numerical instability due to the incompressibility constraint of the stokes problem are analyzed in this paper. The first of them is the stabilization thought the pressure gradient projection, which consists of adding a certain least-squares form of the difference between the pressure gradient and its L² projection onto the discrete velocity space in the variational equations of the problem. The second is a sub-grid scale method, whose stabilization effect is very similar to that of the Galerkin/least-squares method for the Stokes problem. It is shown here that the first method can also be recast in the framework of sub-grid scale method with a particular choice for the space of sub-scales. This leads to a new stabilization procedure, whose applicability to stabilize convection is also studied in this paper.
Abstract
Two apparently different forms of dealing with the numerical instability due to the incompressibility constraint of the stokes problem are analyzed in this paper. The first [...]
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On the constitutive modeling of coupled thermomechanical phase-change problems
C. Agelet de Saracibar, M. Cervera, M. Chiumenti

(1999). Research Report, Nº PI163

Abstract
This paper deals with a thermodynamically consistent numerical formulation for coupled thermoplastic problems including phase-change phenomena and frictional contact. The final goal is to get an accurate, efficient and robust numerical model, able for the numerical simulation of industrial solidification processes. Some of the current issues addressed in the paper are the following. A fractional step method arising from an operator split of the governing differential equations has been used to solve the nonlinear coupled system of equations, leading to a staggered product formula solution algorithm. Nonlinear stability issues are discussed and isentropic and isothermal operator splits are formulated. Within the isentropic split, a strong operator split design constraint is introduced, by requiring that the elastic and plastic entropy, as well as the phase-change induced elastic entropy due to the latent heat, remain fixed in the mechanical problem. The formulation of the model has been consistently derived within a thermodynamic framework. All the material properties have been considered to be temperature dependent. The constitutive behavior has been defined by a thermoviscous/elastoplastic free energy function, including a thermal multiphase change contribution. Plastic response has been modeled by a J2 temperature dependent model, including plastic hardening and thermal softening. The constitutive model proposed accounts for a continuous transition between the initial liquid state, the intermediate mushy state and the final solid state taking place in a solidification process. In particular, a pure viscous deviatoric model has been used at the initial fluid-like state. A thermomecanical contact model, including a frictional hardening and temperature dependent coupled potential, is derived within a fully consistent thermodinamical theory. The numerical model has been implemented into the computational finite element code COMET developed by the authors. Numerical simulations of solidification processes show the good performance of the computational model developed.
Abstract
This paper deals with a thermodynamically consistent numerical formulation for coupled thermoplastic problems including phase-change phenomena and frictional contact. The [...]
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Advances in the stabilized finite point method for structural mechanics
E. Oñate, F. Perazzo, J. Canet

(1999). Research Report, Nº PI164

Abstract
The basis of the finite point method for the fully meshless solution of structure mechanics problems is described. A new stabilization technique based on a finite increment calculus procedure is used. The efficiency and accuracy of the stabilized finite point method in the meshless analysis of simple structural problems is shown in two examples of applications.
Abstract
The basis of the finite point method for the fully meshless solution of structure mechanics problems is described. A new stabilization technique based on a finite increment [...]
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A methodology for analysis of fluid structure interaction accouting for free surface waves
E. Oñate, J. García-Espinosa

(1999). Research Report, Nº PI166

Abstract
A stabilized semi-implicit frictional step finite element method for solving coupled fluid-structure interaction problems involving free surface waves is presented. The stabilized equations are derived at a differential level via a finite element calculus procedure. A new mesh updating technique based on solving a fictitious elastic problem on the moving mesh is described. One example of the efficiency of the stabilized semi-implicit algorithm for the coupled solution of fluid-structure interaction problems is presented.
Abstract
A stabilized semi-implicit frictional step finite element method for solving coupled fluid-structure interaction problems involving free surface waves is presented. The stabilized [...]
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A finite point method for incompressible flow problems
E. Oñate, C. Sacco, S. Idelsohn

(1999). Research Report, Nº PI167

Abstract
A stabilized finite point method (FPM) for meshless analysis of incompressible fluid flow problems is presented. The stabilization approach is based in the finite increment calculus (FIC) procedure developed by Oñate. An enhanced fractional step procedure allowing the semi-implicit numerical solution of incompressible fluids using the FPM is described. Examples of application of the stabilized FPM to the solution of two incompressible flow problems are presented.
Abstract
A stabilized finite point method (FPM) for meshless analysis of incompressible fluid flow problems is presented. The stabilization approach is based in the finite increment [...]
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New rotation free shell triangle for crash-worthiness analysis in parallel PC networks
E. Oñate, F. Zárate, X. Plana, L. Neamtu

(1999). Research Report, Nº PI168

Abstract
A new three node shell triangular element with translational degree of freedom as the only modal variables is presented. The element formulation is based on combining a standard linear finite element interpolation with a cell centered finite volume scheme. Details of the implementation of the element in an explicit dynamic code operating in parallel on networks of PC’s are presented. The efficiency and applicability of the new rotation free shell triangle is shown in the solution of some contact/impact and crash-worthiness problem.
Abstract
A new three node shell triangular element with translational degree of freedom as the only modal variables is presented. The element formulation is based on combining a standard [...]
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Formulación de elementos finitos estabilizada para problemas de transporte convectivo y flujo incompresible mediante técnicas de cálculo finitesimal
E. Oñate

(1999). Research Report, Nº PI169

Abstract
El trabajo muestra que los términos de estabilización para la solución por el MEF de problemas de transporte convectivo y de flujo incompresible, pueden obtenerse de manera natural utilizando aproximaciones de mayor orden en las ecuaciones de balance en un dominio finito. Este procedimiento de cálculo finitesimal permite reinterpretar muchos algoritmos de elementos finitos estabilizados utilizando en la práctica y proporciona también una expresión para calcular los parámetros de estabilización.
Abstract
El trabajo muestra que los términos de estabilización para la solución por el MEF de problemas de transporte convectivo y de flujo incompresible, pueden [...]
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Macroscopic modelling of concrete aging regarding hydration and temperature effects
M. Cervera, R. Faria, J. Oliver, T. Prato

(1999). Research Report, Nº PI170

Abstract
A macroscopic model to account for the hydration and aging phenomena that occur during the early ages of concrete is proposed in this work. Assuming the percolation of water through the hydrates already formed as the dominant mechanism of cement hydration, a normalized variable called hydration degree is adopted in the model, which has an evolution law that can be easily calibrated through an adiabatic calorimetric test. This methodology allows an accurate prediction of the evolution of the hydration degree and the hydration heat production. The evolution of the compressive strength is related to the aging degree, a novel concept which accounts for the effect of the hydration degree and the influence of the curing temperature on the final mechanical properties of concrete, a feature not attended with classic maturity concepts. A wide set of experimental tests validates the proposed model for ordinary and high performance concretes. Fly ash admixture concretes with a large spectrum of cement substitutions can be also modelled with the proposed approach.
Abstract
A macroscopic model to account for the hydration and aging phenomena that occur during the early ages of concrete is proposed in this work. Assuming the percolation of water [...]
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Enrichment and coupling of the finite element and meshless methods
A. Huerta, S. Fernández-Méndez

(1999). Research Report, Nº PI171

Abstract
A mixed hierarchical approximation based on finite elements and meshless methods is presented. Two cases are considered. The first one couples regions where finite elements or meshless methods are used to interpolate: continuity and consistency is preserved. The second one enriches a finite element mesh with processes. In both cases the same formulation is used, convergence is studied and examples are shown.
Abstract
A mixed hierarchical approximation based on finite elements and meshless methods is presented. Two cases are considered. The first one couples regions where finite elements [...]
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Efficient unstructured quadrilateral meshes preserving the prescribed element size
J. Sarrate, A. Huerta

(1999). Research Report, Nº PI172

Abstract
This work devoted to the description of an algorithm for automatic quadrilateral mesh generation. The technique is based on a recursive decomposition of the domain into quadrilateral over complex geometries (there is not need for a previous step where triangles are generated). A background mesh with the desired element sizes allows to obtain the preferred sizes anywhere in the domain. The final mesh can be viewed as the optimal one given the objective function defined. The recursive algorithm induces an efficient data structure which optimizes the computer cost. Several examples are presents to show the efficiency of this algorithm
Abstract
This work devoted to the description of an algorithm for automatic quadrilateral mesh generation. The technique is based on a recursive decomposition of the domain into quadrilateral [...]
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An improved algorithm to smooth graded quadrilateral meshes preserving the prescribed element size
J. Sarrate, A. Huerta

(1999). Research Report, Nº PI173

Abstract
In the generation of quadrilateral unstructured meshes, special attention is focused to the shape of the elements. This is because it is well known that the distortion of the elements and the accuracy of the analysis are closely related. However, in adaptive schemes it is also essential that the new generated mesh meets the prescribed element sizes in order to obtain a solution with the desired precision. In 1982 Giuliani developed a robust rezoning algorithm based on geometrical criteria. It gives proven results is a smooth element size distribution, but elements do not verify the prescribed element size when sharp distributions appear. This paper presents a modification of the Giuliani method that generates non-distorted elements while preserving the element size. Similar to the original method, this modification can be extended to three-dimensional cases
Abstract
In the generation of quadrilateral unstructured meshes, special attention is focused to the shape of the elements. This is because it is well known that the distortion of [...]
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Probabilistic analysis of an a posteriori error estimator for Finite Elements
P. Díez, J. Egozcue

(1999). Research Report, Nº PI175
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EMANT: Programa de análisis de problemas electrotécnicos mediante el método de los elementos finitos
J. Mora, J. Canet, E. Oñate, C. Sacco, L. Martínez

(1999). Research Report, Nº PI177

Abstract
La sencillez conceptual de la electrostática esconde todo un abanico de aplicaciones industriales que precisa de herramientas de cálculo numérico para su optimización. En particular, el diseño de aisladores para sistemas de alta tensión o de las cámaras de tratamiento de alimentos implica una cuidadosa elección de la geometría del sistema y materiales empleados. A la ayuda que supone el conocimiento de la distribución de los campos eléctricos asociados a cada prototipo desde el punto de vista de prestaciones del equipo (homogeneidad de campo, minimización de puntos triples), se añade la interesante posibilidad de contribuir a la comprensión del fenómeno físico (cómo se alteran los alimentos al aplicar un campo eléctrico intenso). Se recoge en las siguientes líneas la formulación desarrollada para escribir un código de resolución de problemas electrostáticos mediante el método de los elementos finitos, no tanto como nuevo problema sino como transición desde otras disciplinas como son la mecánica o transferencia de calor.
Abstract
La sencillez conceptual de la electrostática esconde todo un abanico de aplicaciones industriales que precisa de herramientas de cálculo numérico para [...]
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An anisotropic elastoplastic constitutive model for large deformation analysis of fibre reinforced composites
E. Car, S. Oller, E. Oñate

(1999). Research Report, Nº PI178

Abstract
In this work a generalized anisotropic elastoplastic constitutive model in large deformation is presented. It is used for the analysis of fiber-reinforced composite materials in the frame of the finite element method. Mixing theory is applied to simulate the behavior of the composite material. The elastic anisotropic behavior is simulated with classical elasticity theory, while that of a non-proportional anisotropic solid is simulated by means of the proposed generalized anisotropic elastoplastic model. The approach assumes the existence of a real anisotropic space and of a fictitious isotropic space where a mapped fictitious problem is solved. Both spaces are related by means of a linear transformation using a fourth order tensor incorporating complete information on the real anisotropic material. Details of the numerical implementations of the model into a non-linear, large deformations finite element solution scheme are provided. Examples of application showing the performance of the model for the analysis of fiber-reinforced composite materials are given.
Abstract
In this work a generalized anisotropic elastoplastic constitutive model in large deformation is presented. It is used for the analysis of fiber-reinforced composite [...]
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Numerical aerodynamic analysis of large buildings using a finite element model with application to a telescope building
R. Codina, C. Morton, E. Oñate, O. Soto

(1999). Research Report, Nº PI181

Abstract
Presents a numerical strategy for the aerodynamic analysis of large buildings, with an application to the simulation of the air flow within a telescope building. The finite element formulation is presented first, and then the methodology followed to obtain significant data from the calculations is described. The quality of the ventilation of the building is defined by the average residence times, and the feasibility of this ventilation by the actions created on the instruments and the general flow pattern.
Abstract
Presents a numerical strategy for the aerodynamic analysis of large buildings, with an application to the simulation of the air flow within a telescope building. The finite [...]
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A finite element method for fluid-structure interaction with surface waves using a finite calculus formulation
E. Oñate, J. García-Espinosa

(2000). Research Report, Nº PI180

Abstract
A stabilized semi-implicit step finite element method for solving coupled fluid-structure interaction problems involving free surface waves is presented. The stabilized governing equations for the viscous fluid and the free surface are derived at a differential level via finite increment calculus procedure. A mesh updating technique based on solving a fictitious elastic problem on the moving mesh is described. Examples of the efficiency of the stabilized semi-implicit algorithm for the analysis of fluid-structure interaction problems in totally or partially submerged bodies is presented.
Abstract
A stabilized semi-implicit step finite element method for solving coupled fluid-structure interaction problems involving free surface waves is presented. The stabilized governing [...]
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Stabilization techniques for finite element analysis of convection-diffusion problems
E. Oñate, M. Manzan

(2000). Research Report, Nº PI183

Abstract
The accurate solution of convection type problems on practical grids has been ever a challenging issue, and invariably some sort of stabilization is needed in order to get a physical solution. This has pushed researchers to develop various stabilization algorithms used in every day practice by numerical analysts. In this chapter some methods are presented along with a new finite increment calculus approach to obtain the different algorithms using higher order conservation equations.
Abstract
The accurate solution of convection type problems on practical grids has been ever a challenging issue, and invariably some sort of stabilization is needed in order to get [...]
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The Monte Carlo method. Application to the stochastic analysis of sheet stamping processes
J. Hurtado, F. Zárate, E. Oñate

(2000). Research Report, Nº PI184

Abstract
Stochastic Mechanics is a rapidly growing area of research, whose importance is being recognized not only in academic circles but also in industrial practice. This is no doubt due to the fact that most structural properties and loads are either random or uncertain. The first term refers to a natural chaotic variation of the parameter, while the second is associated to the human lack of knowledge about it. Both kinds of unpredictability work together in rendering doubtful the results of a (usually single) deterministic mechanical analysis. When thinking about the randomness and uncertainty linked to all physical parameters and phenomena a big question mark closes the large list of numbers produced by a finite element calculation. In Stochastic Mechanics there are several techniques to analyse the natural scatter of strains and stresses caused by the dispersion in the given loads and/or the structural parameters. The most general one is the Monte Carlo method. However, it must be recognized that is as well the most costly in computational terms. Nevertheless, this cost has becoming feasible with the advance in Computer Science, specially with the advent of parallel computing, due to the fact that a Monte Carlo calculation is intrinsically a task that can be performed in parallel. The present report is intended to provide the reader an introduction to the Monte Carlo method in the context of Computational Mechanics. The technique is applied to the analysis of the uncertainty spread in a stamping process. The first chapter summarises the Monte Carlo method and its theoretical backgrounds. The second chapter is devoted to the case study, namely, the stochastic analysis of a square cup deep drawing problem. Finally, the basic equations governing the mechanical modelling of the stamping process are summarized in the appendix.
Abstract
Stochastic Mechanics is a rapidly growing area of research, whose importance is being recognized not only in academic circles but also in industrial practice. This is no doubt [...]
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Stabilized finite element approximation of transient incompressible flows using orthogonal subscales
R. Codina

(2000). Research Report, Nº PI185

Abstract
In this paper we present a stabilized finite element formulation to solve the Oseen equations as a model problem involving both convection effects and the incompressibility restriction. The need for stabilization techniques to solve this problem arises because of the restriction in the possible choices for the velocity and pressure spaces dictated by the inf-sup condition, as well as the instabilities encountered when convection is dominant. Both can be overcome by resorting from the standard Galerkin method to a stabilized formulation. The one presented here is based on the subgrid scale concept, in which unresolvable scales of the continuous solution are approximately accounted for. In particular, the approach developed herein is based on the assumption that unresolved subscales are orthogonal to the finite element space. The motivation of the method is fully described. It is also shown that this formulation is table and optimally convergent for an adequate choice of the algorithmic on which the method depends.
Abstract
In this paper we present a stabilized finite element formulation to solve the Oseen equations as a model problem involving both convection effects and the incompressibility [...]
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Pressure stability in fractional step finite element methods for incompressible flows
R. Codina

(2000). Research Report, Nº PI186

Abstract
The objective of this paper is to analyze the pressure stability of fractional step finite element methods for incompressible flows. For the classical first order projection method, it is shown that there is a pressure control which depends on the time step size, and therefore there is a lower bound for this time step for stability reasons. The situation is much worse for a second order scheme in which part of the extremely weak. To overcome these shortcomings, a stabilized fractional step finite element method is also considered, and its stability is analyzed. Some simple numerical examples are presented to support the theoretical results.
Abstract
The objective of this paper is to analyze the pressure stability of fractional step finite element methods for incompressible flows. For the classical first order projection [...]
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Implementation of a stabilized finite element formulation for the incompressible Navier-Stokes equations based on a pressure gradient projection
R. Codina, J. Blasco, G. Buscaglia, A. Huerta

(2000). Research Report, Nº PI187

Abstract
We discuss in this paper some implementation aspects of a finite element formulation for the incompressible Navier-Stokes which allows the use of equal order velocity-pressure interpolations. The method consists in introducing the project of the pressure gradient and adding the difference between the pressure Laplacian and divergence of this new field to the incompressibility equations, both multiplied by suitable algorithmic parameters. The main purpose of this paper is to discuss how to deal with the new variable in the implementation of the algorithm. Obviously, it could be treated as one extra unknown, either explicitly or as a condensed variable. However, we take for granted that the only way or another. Here we discuss some iterative schemes to perform this uncoupling of the pressure gradient projection (PGP) from the calculation of the velocity and the pressure, both for stationary and the transient of the linearization loop and the iterative segregation of the PGP, whereas in the second the main dilemma concerns the explicit or implicit treatment of the PGP.
Abstract
We discuss in this paper some implementation aspects of a finite element formulation for the incompressible Navier-Stokes which allows the use of equal order velocity-pressure [...]
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Prediction of damage and failure in civil engineering structures using a finite element model.
E. Oñate, A. Hanganu, J. Canet

(2000). Research Report, Nº PI188

Abstract
The paper describes a finite element damage model for non linear analysis of concrete or reinforced structures. It is show how can be effectively used to predict local and global damage up to structural failure. Examples of applications of the model to the analysis of different structures such as a nuclear containment shell, a housing building and the domes of St. Mark Basilica are presented.
Abstract
The paper describes a finite element damage model for non linear analysis of concrete or reinforced structures. It is show how can be effectively used to predict local and [...]
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Andragogy and training of entrepreneurs at UNESR Bolívar
M. Doubront

correspondencias & análisis (2019). 11

Abstract
Given the complex crisis experienced by Venezuela, which has provoked a systematic defection of university students, there is a need to structure a training plan for entrepreneurs, to create new businesses, where youth have a leading role, strengthening a culture of entrepreneurship compatible with Andragogical, participatory and flexible philosophy of Universidad Nacional Experimental Simón Rodríguez (UNESR).
Abstract
Given the complex crisis experienced by Venezuela, which has provoked a systematic defection of university students, there is a need to structure a training plan for entrepreneurs, [...]
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Vulnerability of social communication students. A case study
P. Echeverry

correspondencias & análisis (2019). 10

Abstract
This article start with a research completed in 2018, whose goal was to identify situations and causes of physical, emotional, social and economic vulnerability of the students of the Social Communication´s program. In pursuit of this aim, four discussion groups, 125 surveys shaped with 49 closed questions each, provided the information for the analysis. The results of the research, enabled the identification of some socioeconomic characteristics of the students, such as that the program average student lives in low-middle class neighborhoods, does not get to have three proper meals a day and depends on his family to pay their student fees and their sustenance. The research also showed that belonging to the LGBTIQ+ population, parenting, and financial difficulties, represent some bigger student vulnerability conditions which impact in the quality of the training environment and the forming process itself.
Abstract
This article start with a research completed in 2018, whose goal was to identify situations and causes of physical, emotional, social and economic vulnerability of the students [...]
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Informative treatment of the mapuches in the newspaper El Mercurio. A content analysis based on the Framing Theory
C. Valle-Rojas, M. Ruiz, F. Verdú, F. Silva-Layera

correspondencias & análisis (2019). 9

Abstract
This paper analyzes the information treatment of the Mapuche people in the newspaper El Mercurio during two periods. First, between 1950 and 1973 (twentieth century); and second, during the years 2010, 2013 and 2014, (21st century). To this end, a corpus of 340 journalistic texts has been selected, of which 147 correspond to the 20th century (1950-1970) and 193, to the 21st century (2010, 2013-2014). The analysis shows that most of the frames are linked to conflicts, criminal prosecutions and arson attacks; so that El Mercurio prioritizes connotations and negative events to inform about the Mapuche indigenous people.
Abstract
This paper analyzes the information treatment of the Mapuche people in the newspaper El Mercurio during two periods. First, between 1950 and 1973 (twentieth century); and [...]
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The contribution of social communication to projects of rehabilitation of water and sanitation networks: The case of Sedapal Project Lote 3
W. Alva

correspondencias & análisis (2019). 8

Abstract
This paper focus on implementation of communication strategies developed in the Rehabilitation of Potable Water and Sewerage Network Lote 3 project, executed between 2013 and 2014 in the district of Comas, north of Lima-Peru, and belonging to the Servicio de Agua Potable y Alcantarillado de Lima (SEDAPAL), company responsible for water and sewage in Lima. As a result, it could be observed that the implementation of a diagnosis of perceptions, the communication plan and the communication and education products allowed to facilitate the design of messages according to the context of the project, taking into account the speeches of the users against and in favor of the project, as well as the objectives sought by the executing company.
Abstract
This paper focus on implementation of communication strategies developed in the Rehabilitation of Potable Water and Sewerage Network Lote 3 project, executed between 2013 [...]
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Public Relations in electoral campaigns
A. Zepeda

correspondencias & análisis (2019). 7

Abstract
The essay makes a description of the strategical role the play public relations during electoral campaigns. In the beginning, the essay conceptualizes public relations and its connection with political campaigns. It is argued that make an electoral campaign imply a public relation activity with the objective of knowing the voters and make up different political strategies to get their votes and, consequently, avoid the opposition can win the political power. It is concluded that the successful in a political campaigns depends on the creative, intelligent and innovative use of public relations.
Abstract
The essay makes a description of the strategical role the play public relations during electoral campaigns. In the beginning, the essay conceptualizes public relations and [...]
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Transmedia Storytelling and Construction of Fictional Worlds: Aliados Series as Case Study
T. Atarama-Rojas

correspondencias & análisis (2019). 6

Abstract
This paper explores the contributions of transmedia storytelling in the construction of fictional worlds, in an attempt to detect the narrative elements that strengthen the bond of the audience with the fictional world. The study shows that based on the solid construction of the poetics of a story, transmedia storytelling can enrich the engagement with a large audience. To prove this, we analyze the narrative elements and the transmedia strategies of the series Aliados, produced by Cris Morena Group and broadcasted in Latin America and countries in Europe
Abstract
This paper explores the contributions of transmedia storytelling in the construction of fictional worlds, in an attempt to detect the narrative elements that strengthen the [...]
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Strategy and management, the foundations of any successful brand
S. Escalada

correspondencias & análisis (2019). 5

Abstract
When analyzing any branding work we tend to simplify a process that by its nature is enormously complex and multidisciplinary. There is an important current of opinion that tends to reduce the creation of a brand to its logo or to the group of elements that will articulate the visual identity in a sort of cosmetic image, or purely aesthetic. Either by understanding branding as a superficial expense and not as a strategic investment, due to ignorance of the discipline, short-sightedness, lack of means and / or professionals or, by a mixture of all these factors, the brands themselves devalue in many cases from the moment they make the decision not to face their construction in a studied way, serious and coherent.
Abstract
When analyzing any branding work we tend to simplify a process that by its nature is enormously complex and multidisciplinary. There is an important current of opinion that [...]
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Andragogy and training of entrepreneurs at UNESR Bolívar
M. Doubront

Petronila Liz Contreras Yalico's personal collection (2019). 6

Abstract
Given the complex crisis experienced by Venezuela, which has provoked a systematic defection of university students, there is a need to structure a training plan for entrepreneurs, to create new businesses, where youth have a leading role, strengthening a culture of entrepreneurship compatible with Andragogical, participatory and flexible philosophy of Universidad Nacional Experimental Simón Rodríguez (UNESR).
Abstract
Given the complex crisis experienced by Venezuela, which has provoked a systematic defection of university students, there is a need to structure a training plan for entrepreneurs, [...]
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Vulnerability of social communication students. A case study
P. Echeverry

Petronila Liz Contreras Yalico's personal collection (2019). 7

Abstract
This article start with a research completed in 2018, whose goal was to identify situations and causes of physical, emotional, social and economic vulnerability of the students of the Social Communication´s program. In pursuit of this aim, four discussion groups, 125 surveys shaped with 49 closed questions each, provided the information for the analysis. The results of the research, enabled the identification of some socioeconomic characteristics of the students, such as that the program average student lives in low-middle class neighborhoods, does not get to have three proper meals a day and depends on his family to pay their student fees and their sustenance. The research also showed that belonging to the LGBTIQ+ population, parenting, and financial difficulties, represent some bigger student vulnerability conditions which impact in the quality of the training environment and the forming process itself.
Abstract
This article start with a research completed in 2018, whose goal was to identify situations and causes of physical, emotional, social and economic vulnerability of the students [...]
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El Caso Mundial and El Caso Criminal, new weekly papers in Spain after the disappearance of El Caso (1952-1987)
R. Cárcela

correspondencias & análisis (2019). 3

Abstract
The paper analyses “El Caso Mundial” and “El Caso Criminal”, both of them event newspapers that emerged in Spain after the disappearance of "El Caso" (Madrid, 1952-1987), and was published by the businessman and journalist Joaquín Abad. Few research has been done on this newspaper that came to fill the gap left by "El Caso", directed by Eugenio Suárez. The sources consulted show that it was really a new journalistic publication, similar to the original one, but different. Therefore, it cannot be considered a second stage. It was printed and distributed from Almería for ten years (1987-1997), although it had a national scope. His informative style, content, directors and the causes that led to its completion on September 24, 1997.
Abstract
The paper analyses “El Caso Mundial” and “El Caso Criminal”, both of them event newspapers that emerged in Spain after the disappearance of "El [...]
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The concept of Chronicle: An overview from Social and Human Sciences contributions
J. Altamar

correspondencias & análisis (2019). 2

Abstract
We reflect on the concept of the Latin American chronicle from the understanding that to build it, testimonial is not enough, but that additional criteria must be taken into account from the theories of narration, literature, social psychology, anthropology symbolic and ethnography. To this are added the contributions of the journalistic-literary tendencies of the North American style, which, in turn, were nourished by the approaches of the nineteenth-century European realist novel. The result is a concept in which the chronicle is located as a genre of a creative and narrative nature, with a particular voice and tone of marked literary influence, with which the reality that is recreated -be it character, place, situation or event-, both from factors of typical interest from journalism, as from the meaningful everyday life.
Abstract
We reflect on the concept of the Latin American chronicle from the understanding that to build it, testimonial is not enough, but that additional criteria must be taken into [...]
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Manipulación fotográfica y credibilidad del medio periodístico a través de la fotografía
G. García

correspondencias & análisis (2019). 4

Abstract
El presente estudio tiene como objetivo conocer de qué manera la manipulación fotográfica se relaciona con la credibilidad del medio periodístico a través de la fotografía publicada en el diario Los Angeles Times, referida a la Segunda Guerra del Golfo en el 2003. El diseño de investigación es no experimental, con corte trasversal; tipo de investigación aplicativa; nivel de investigación descriptivo, correlacional y comparativo; método de investigación inductivo, deductivo, analítico, estadístico y hermenéutico. Con unidades de análisis y muestras de población de estudiantes de Lima y Nueva York, se confirma la hipótesis general que hace referencia a la relación significativa entre la manipulación fotográfica y la credibilidad del medio periodístico, al tomarse en consideración el material fotográfico publicado en el diario Los Angeles Times durante la Segunda Guerra del Golfo en el 2003.
Abstract
El presente estudio tiene como objetivo conocer de qué manera la manipulación fotográfica se relaciona con la credibilidad del medio periodístico [...]
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Informative treatment of the mapuches in the newspaper El Mercurio. A content analysis based on the Framing Theory
C. Valle-Rojas, J. García-Espinosa, F. Verdú, F. Silva-Layera

Petronila Liz Contreras Yalico's personal collection (2019). 5

Abstract
This paper analyzes the information treatment of the Mapuche people in the newspaper El Mercurio during two periods. First, between 1950 and 1973 (twentieth century); and second, during the years 2010, 2013 and 2014, (21st century). To this end, a corpus of 340 journalistic texts has been selected, of which 147 correspond to the 20th century (1950-1970) and 193, to the 21st century (2010, 2013-2014). The analysis shows that most of the frames are linked to conflicts, criminal prosecutions and arson attacks; so that El Mercurio prioritizes connotations and negative events to inform about the Mapuche indigenous people.
Abstract
This paper analyzes the information treatment of the Mapuche people in the newspaper El Mercurio during two periods. First, between 1950 and 1973 (twentieth century); and [...]
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The contribution of social communication to projects of rehabilitation of water and sanitation networks: The case of Sedapal Project Lote 3
W. Alva

Correspondencias & análisis (2019). n°9

Abstract
This paper focus on implementation of communication strategies developed in the Rehabilitation of Potable Water and Sewerage Network Lote 3 project, executed between 2013 and 2014 in the district of Comas, north of Lima-Peru, and belonging to the Servicio de Agua Potable y Alcantarillado de Lima (SEDAPAL), company responsible for water and sewage in Lima. As a result, it could be observed that the implementation of a diagnosis of perceptions, the communication plan and the communication and education products allowed to facilitate the design of messages according to the context of the project, taking into account the speeches of the users against and in favor of the project, as well as the objectives sought by the executing company.
Abstract
This paper focus on implementation of communication strategies developed in the Rehabilitation of Potable Water and Sewerage Network Lote 3 project, executed between 2013 [...]
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Public Relations in electoral campaigns
A. Zepeda

Correspondencias & análisis (2019). n°9

Abstract
The essay makes a description of the strategical role the play public relations during electoral campaigns. In the beginning, the essay conceptualizes public relations and its connection with political campaigns. It is argued that make an electoral campaign imply a public relation activity with the objective of knowing the voters and make up different political strategies to get their votes and, consequently, avoid the opposition can win the political power. It is concluded that the successful in a political campaigns depends on the creative, intelligent and innovative use of public relations.
Abstract
The essay makes a description of the strategical role the play public relations during electoral campaigns. In the beginning, the essay conceptualizes public relations and [...]
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Transmedia Storytelling and Construction of Fictional Worlds: Aliados Series as Case Study
T. Atarama-Rojas

Petronila Liz Contreras Yalico's personal collection (2019). 2

Abstract
This paper explores the contributions of transmedia storytelling in the construction of fictional worlds, in an attempt to detect the narrative elements that strengthen the bond of the audience with the fictional world. The study shows that based on the solid construction of the poetics of a story, transmedia storytelling can enrich the engagement with a large audience. To prove this, we analyze the narrative elements and the transmedia strategies of the series Aliados, produced by Cris Morena Group and broadcasted in Latin America and countries in Europe.
Abstract
This paper explores the contributions of transmedia storytelling in the construction of fictional worlds, in an attempt to detect the narrative elements that strengthen the [...]
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Strategy and management, the foundations of any successful brand
S. Escalada

Correspondencias & análisis (2019). n°9

Abstract
When analyzing any branding work we tend to simplify a process that by its nature is enormously complex and multidisciplinary. There is an important current of opinion that tends to reduce the creation of a brand to its logo or to the group of elements that will articulate the visual identity in a sort of cosmetic image, or purely aesthetic. Either by understanding branding as a superficial expense and not as a strategic investment, due to ignorance of the discipline, short-sightedness, lack of means and / or professionals or, by a mixture of all these factors, the brands themselves devalue in many cases from the moment they make the decision not to face their construction in a studied way, serious and coherent.
Abstract
When analyzing any branding work we tend to simplify a process that by its nature is enormously complex and multidisciplinary. There is an important current of opinion that [...]
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2nd FIBRESHIP WORKSHOP - Overall description of the FIBRESHIP project
A. Jurado

Open Access Repository of the FIBRESHIP project (2019). 12

Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP project offered to the participants a chance to discuss the different composite materials solutions for shipbuilding as well as learn more about the latest technological advances of FIBRESHIP Project related to design, construction and operation of ships integrally built in composite materials. FIBRESHIP Consortium is looking for a niche in the future shipping market through promoting changes in the regulatory framework of IMO and generating guidelines and methodologies for designing, building and operating large-length vessels, laying the foundations of a new market based on composites technology in shipbuilding and shipping. This presentation introduces the Fibreship project, which addresses the feasibility of the construction of large-length vessels using uniquely lightweight composite materials in their structures. Alfonso explained the significant advantages of the massive application of lightweight composite materials in design, construction and operation of large-length ships. The main challenge of this project is to generate a discussion in regulatory bodies through the advances and developments reached in the project in order to promote new rules and regulations that allows the integral construction of ships over 500 GT (approx. 50 meters in length) in FRP materials, which will result in the development of a new European market based on the construction of lightweight ships.
Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP [...]
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2nd FIBRESHIP WORKSHOP - Durability of sandwich structures, fatigue testing and recent advances in fire strength modeling
P. Casari

Open Access Repository of the FIBRESHIP project (2019). 6

Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP project offered to the participants a chance to discuss the different composite materials solutions for shipbuilding as well as learn more about the latest technological advances of FIBRESHIP Project related to design, construction and operation of ships integrally built in composite materials. FIBRESHIP Consortium is looking for a niche in the future shipping market through promoting changes in the regulatory framework of IMO and generating guidelines and methodologies for designing, building and operating large-length vessels, laying the foundations of a new market based on composites technology in shipbuilding and shipping. This presentation shows interesting results about the mechanical behaviour of sandwich structures under cyclic fatigue stresses. To address this study, a wide variety of experimental tests as per example digital image correlation or tomography analysis were carried out to investigate the failure modes of these materials. Moreover, the fire behaviour of these sandwich structures is investigated using advanced simulation tools based on finite element analysis.
Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of [...]
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2nd FIBRESHIP WORKSHOP - Breakout Session 1 - Materials
X. Martinez

Open Access Repository of the FIBRESHIP project (2019). 9

Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP project offered to the participants a chance to discuss the different composite materials solutions for shipbuilding as well as learn more about the latest technological advances of FIBRESHIP Project related to design, construction and operation of ships integrally built in composite materials. FIBRESHIP Consortium is looking for a niche in the future shipping market through promoting changes in the regulatory framework of IMO and generating guidelines and methodologies for designing, building and operating large-length vessels, laying the foundations of a new market based on composites technology in shipbuilding and shipping. This presentation explains the development of a new methodology for the selection of composites for marine applications, which has been developed within the FIBRESHIP project. This methodology is based on an extensive characterization of the mechanical and fire properties of the potential composites which would be used by designers in the construction of new fibre ships. On top of that, Xavier presented a new type of structural joining connections between the modules and composite sections of the ship which facilitates the structure disassembly.
Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP [...]
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2nd FIBRESHIP WORKSHOP - RAMSSES demo case
E. Billaudeau

Open Access Repository of the FIBRESHIP project (2019). 11

Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP project offered to the participants a chance to discuss the different composite materials solutions for shipbuilding as well as learn more about the latest technological advances of FIBRESHIP Project related to design, construction and operation of ships integrally built in composite materials. FIBRESHIP Consortium is looking for a niche in the future shipping market through promoting changes in the regulatory framework of IMO and generating guidelines and methodologies for designing, building and operating large-length vessels, laying the foundations of a new market based on composites technology in shipbuilding and shipping. In the first section of his presentation, the main objectives of the RAMSSES project are explained (reduction of the weight using multifunctional materials, selection of optimum materials and structural connections for the construction of lightweight ships, etc.). In the second one, it is explained in detail the technical progresses and the experimental and numerical results obtained the in the project up to now.
Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP [...]
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2nd FIBRESHIP WORKSHOP - At the forefront of technology
T. Iturgaiz

Open Access Repository of the FIBRESHIP project (2019). 7

Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP project offered to the participants a chance to discuss the different composite materials solutions for shipbuilding as well as learn more about the latest technological advances of FIBRESHIP Project related to design, construction and operation of ships integrally built in composite materials. FIBRESHIP Consortium is looking for a niche in the future shipping market through promoting changes in the regulatory framework of IMO and generating guidelines and methodologies for designing, building and operating large-length vessels, laying the foundations of a new market based on composites technology in shipbuilding and shipping. In this presentation, Txuma Iturgáiz on behalf of MTorres introduced the field of activity of his company which is focused on the development of new innovative machines with a high level of automatization for manufacturing and testing composite laminates. Txuma suggested that the most advanced technologies for composite manufacturing can be applied for the shipyards in the construction of a new generation of lightweight ships with the advantages of reasonable cost, flexibility and outstanding quality, extrapolating the advances reached in aeronautical and automotive sectors.
Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop [...]
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2nd FIBRESHIP WORKSHOP - Breakout Session 2 - Computational Analysis Tools
J. García-Espinosa

Open Access Repository of the FIBRESHIP project (2019). 8

Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP project offered to the participants a chance to discuss the different composite materials solutions for shipbuilding as well as learn more about the latest technological advances of FIBRESHIP Project related to design, construction and operation of ships integrally built in composite materials. FIBRESHIP Consortium is looking for a niche in the future shipping market through promoting changes in the regulatory framework of IMO and generating guidelines and methodologies for designing, building and operating large-length vessels, laying the foundations of a new market based on composites technology in shipbuilding and shipping. This presentation explains the development of a new software suite with a wide variety of ad-hoctools to simulate the structural and fire performance of the lightweight composite ships developed within the FIBRESHIP project. The computational analysis tool is based on a fast-numerical software which can be used for the simulation of fatigue, fire diagnosis, thermal propagation, hydro-structural analysis and so on. A Betha version of the developed software suite of this numerical tool is available for the partners of the project.
Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP [...]
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2nd FIBRESHIP WORKSHOP - Breakout Session 3 - Production / Demonstrator
J. Rasmussen, E. Waldura

Open Access Repository of the FIBRESHIP project (2019). 5

Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP project offered to the participants a chance to discuss the different composite materials solutions for shipbuilding as well as learn more about the latest technological advances of FIBRESHIP Project related to design, construction and operation of ships integrally built in composite materials. FIBRESHIP Consortium is looking for a niche in the future shipping market through promoting changes in the regulatory framework of IMO and generating guidelines and methodologies for designing, building and operating large-length vessels, laying the foundations of a new market based on composites technology in shipbuilding and shipping. This presentation is focussed on the development of efficient production methodologies and automatized processes which can be efficiently used for the construction of large-length composite ships by the shipyards. Furthermore, it describes the technical feasibility of the construction of the demonstrator of the project using exclusively lightweight composite materials.
Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP [...]
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2nd FIBRESHIP WORKSHOP - Breakout Session 4 - Regulatory and Standardisation
R. Devalapalli, S. Paboeuf

Open Access Repository of the FIBRESHIP project (2019). 10

Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP project offered to the participants a chance to discuss the different composite materials solutions for shipbuilding as well as learn more about the latest technological advances of FIBRESHIP Project related to design, construction and operation of ships integrally built in composite materials. FIBRESHIP Consortium is looking for a niche in the future shipping market through promoting changes in the regulatory framework of IMO and generating guidelines and methodologies for designing, building and operating large-length vessels, laying the foundations of a new market based on composites technology in shipbuilding and shipping. This presentation is dedicated to the strategies of regulatory and standardization activities of the project, mainly focused on the fire challenges related to the use of composites in the shipping industry. Reddy Devalapalli (Lloyd’s Register of Shipping) explained that a presentation in collaboration with RAMSSES project is being prepared for the next SDC of IMO in February 2020 as well as a info paper, to promote changes in the current regulatory frameworks which limit the use of Fibre Reinforced Plastic elements in the construction of large-length ship structures. In addition, Stephane Pabeouf from Bureau Veritas described the development of new performance criteria which will attempt to deal with the fire safety issues and structural performance of the new lightweight ships, being an essential part of the FIBRESHIP project.
Abstract
Presentation held at the second public workshop of the FIBRESHIP project, held at La Ciotat, France, on 25th of June 2019. The second public workshop of the FIBRESHIP [...]
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Rigid-flexible body analysis without rotation parameters
R. Taylor

(2000). Research Report, Nº PI189

Abstract
This paper addresses the coupled flexible and rigid body response of solids undergoing large motions and deformations. The formulation is presented in a form which is free of rotation parameters and thus avoids the need of finding compatible integration formulae for translations and rotations. The motion of each rigid body is represented in terms of the nodal parameters of a simplex element subject to constraints which ensure rigid motions. Flexible structural members for rods and shells are then expressed in terms of displacement and relative displacement parameters leading to total system of equations involving only translation degrees of freedom. The motions are integrated using classical energy and momentum conserving schemes, thus leading to systems which are unconditionally stable for Hamiltonian (elastic-rigid) systems. The only requirement for absolute stability is that the non-linear algebraic equations representing the solution at each time step must converge. The formulation is illustrated in two dimensions by representative numerical problems which involve both rigid and flexible parts or multi-rigid body situations. In all cases the conservation properties are observed.
Abstract
This paper addresses the coupled flexible and rigid body response of solids undergoing large motions and deformations. The formulation is presented in a form which is free [...]
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locking in the incompressible limit for the element free galerkin method
A. Huerta, S. Fernández-Méndez

(2000). Research Report, Nº PI190

Abstract
Volumetric locking (locking in the incompressible limit) for linear elastic isotropic materials is studied in the context of the Element Free Galerkin method. The modal analysis developed here shows here shows that the number of non-physical locking modes is independent of the dilation parameter (support of the interpolation functions). Thus increasing the dilation parameter does not suppress locking. Nevertheless, an increase in the dilation parameter does reduce the energy associated to the non-physical locking behavior. Although more locking modes are present in the Element Free Galerkin method with quadratic consistency than with the standard biquadratic finite element method. Finally, numerical examples are shown.
Abstract
Volumetric locking (locking in the incompressible limit) for linear elastic isotropic materials is studied in the context of the Element Free Galerkin method. The modal analysis [...]
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Límites de los métodos numéricos
E. Oñate

(2000). Research Report, Nº PI191

Abstract
Se plantean en el artículo los límites de los métodos numéricos para resolver cualquier problema que afecte a la vida del hombre. Se discute la capacidad de la razón para expresar todos los problemas del universo en forma matemática, y la posibilidad de encontrar su solución en forma numérica. Finalmente, se especula sobre el alcance y posibilidad de los métodos numéricos en el amplio campo de las ciencias sociales
Abstract
Se plantean en el artículo los límites de los métodos numéricos para resolver cualquier problema que afecte a la vida del hombre. Se discute la [...]
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El bucle de los números
E. Oñate

(2000). Research Report, Nº PI192

Abstract
El artículo presenta una sucinta panorámica sobre la evolución de los métodos numéricos dese la antigua Babilonia hasta nuestros días. Se destaca como la máxima Pitagórica de que “todo es número”, adquiere plena actualidad en nuestros días, en que, con la ayuda de los ordenadores, podemos dar respuestas numéricas a prácticamente cualquier problema que afecte a la vida del hombre. Recorriendo ese bucle de los números se relata brevemente en el artículo como la humanidad ha evolucionado paralelamente en su aspiración de cuantificar los fenómenos de la naturaleza, y como el paso de los pueblos ha ido de la mano de los avances en expresar numéricamente la solución de sus problemas más cotidianos.
Abstract
El artículo presenta una sucinta panorámica sobre la evolución de los métodos numéricos dese la antigua Babilonia hasta nuestros días. [...]
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Simulación por ordenador del comportamiento resistente de estructuras: El laboratorio virtual de estructuras
E. Oñate, A. Hanganu, J. Miquel, B. Suárez

(2000). Research Report, Nº PI193

Abstract
Se presenta el concepto de Laboratorio Virtual de Estructuras (LAVE) para evaluar por ordenador la capacidad resistente de estructuras de hormigón y el coeficiente de seguridad al colapso utilizando modelos de cálculo no lineal basados en la teoría del daño y el método de elementos finitos. Se describen diversos ejemplos de aplicación del LAVE al análisis de la resistencia última de estructuras de hormigón en masa y armado.
Abstract
Se presenta el concepto de Laboratorio Virtual de Estructuras (LAVE) para evaluar por ordenador la capacidad resistente de estructuras de hormigón y el coeficiente [...]
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Del ábaco de fichas a Internet
E. Oñate

(2000). Research Report, Nº PI194
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The braid of numbers
E. Oñate

(2000). Research Report, Nº PI195
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Meshless analysis of incompressible flows using the Finite Point Method
E. Oñate, C. Sacco, S. Idelsohn

(2000). Research Report, Nº PI196

Abstract
A stabilized finite point method (FPM) for meshless analysis of incompressible fluid flows is presented. The stabilization approach is based in the finite calculus (FIC) procedure. An enhanced fractional step procedure allowing the semi-implicit numerical solution of incompressible fluids using the PFM is described. Examples of application of the stabilized FPM to the solution of incompressible flows problems are presented.
Abstract
A stabilized finite point method (FPM) for meshless analysis of incompressible fluid flows is presented. The stabilization approach is based in the finite calculus (FIC) procedure. [...]
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Stabilized finite element approximation of transient incompressible flows using orthogonal subscales
R. Codina

(2000). Research Report, Nº PI197

Abstract
In this paper we present a stabilized finite element method to solve the transient Navier-Stokes equations based on the decomposition of the unknowns into resolvable and sub grid scales. The latter are approximately accounted for, so as to end up with a stable finite element problem which, in particular, allows to deal with convection-dominated flows and the use of equal velocity-pressure interpolations. Three main issues are addressed. The first is a method to estimate the behavior of the stabilization parameters based on a Fourier analysis of the problem for the subscales. Secondly, the way to deal with transient problems discretized using a finite difference scheme is discussed. Finally, the treatment of the nonlinear term is also analyzed. A very important feature of this work is that the sub grid scales are taken as orthogonal to the finite element space. In the transient case, this simplifies considerably the numerical scheme.
Abstract
In this paper we present a stabilized finite element method to solve the transient Navier-Stokes equations based on the decomposition of the unknowns into resolvable and sub [...]
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On isotropic scalar damage models for the numerical analysis of concrete structures
R. Faria, J. Oliver, M. Cervera

(2000). Research Report, Nº PI198

Abstract
Within the framework of Continuum Damage Mechanics some isotropic scalar damage models for concrete are revisited, with emphasis on a recent one proposed by the authors. This scalar damage model is based on the assumption that a stress split is required to capture unilateral behaviour exhibited by concrete when passing from tension to compression. Similar assumptions are pursued on many scalar damage models, yet with many differences being encountered on the strategies adopted for the implementation of such split, which sometimes is performed over the strain tensor. In this paper a discussion on the implications of those splits is conducted, as well as on the norms that define the elastic domain in the stress space. For the proposed damage model a strain-driven formalism is adopted, but the stress split is performed on the effective elastic stress tensor, which is shown to correspond to a split of the Cauchy stress tensor. This strategy improves the algorithmic efficiency as much as required for the seismic analysis of large-scale problems, and circumvents many of the drawbacks present in similar damage models. Besides, two scalar damage variable are introduced as internal variables, as well as an inelastic strain tensor. Efficiency of the proposed constitutive model is illustrated through numerical applications. Algorithmic implementation is also detailed.
Abstract
Within the framework of Continuum Damage Mechanics some isotropic scalar damage models for concrete are revisited, with emphasis on a recent one proposed by the authors. This [...]
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Interface GiD-SAP90 elemento ASOLID
J. Maristany, F. Salinas, A. Mestre

(2000). Research Report, Nº PI199
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A Second Order Semi-Lagrangian Particle Finite Element Method for Fluid Flows
J. Colom Cobb, J. García-Espinosa, B. Servan Camas, P. Nadukandi

Computational Particle Mechanics (2019).

Abstract
In this paper, a second order SL-PFEM scheme for solving the incompressible Navier-Stokes equations is presented. This scheme is based on the second order velocity Verlet algorithm, which uses an explicit integration for the particle’s trajectory and an implicit integration for the velocity. The algorithm is completed with a predictor-multicorrector scheme for the integration of the velocity correction using the Finite Element Method. A second order projector based on least squares is used to transfer the intrinsic variables information from the particles onto the background mesh, while a second order interpolation scheme is used to transfer the accelerations from the mesh to the particles. Convergence analyses are carried out to assess the second order convergence.
Abstract
In this paper, a second order SL-PFEM scheme for solving the incompressible Navier-Stokes equations is presented. This scheme is based on the second order velocity Verlet [...]
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Desarrollos y aplicaciones de modelos de fractura en la escuela de ingenieros de caminos de Barcelona
E. Oñate

(2000). Research Report, Nº PI201

Abstract
El artículo es una panorámica de los aspectos teóricos y algunas aplicaciones prácticas de los modelos de fractura desarrollados por diversos grupos en la Escuela de Ingenieros de Caminos de Barcelona (EICB) durante los últimos quince para el análisis no lineal de estructuras. La motivación fundamental para el desarrollo de estos modelos se centra en el análisis de la seguridad de estructuras de hormigón en masa y armado. La mayor parte de los modelos se basan en la teoría de daño continuo y utilizan el método de los elementos finitos para la solución numérica. Los modelos de daño se han extendido y aplicado también con éxito el análisis de diversas estructuras de edificios históricos. Los desarrollos más recientes de estos modelos en la EICB incluyen la predicción de fenómenos de localización en estructuras de hormigón y el análisis del comportamiento no lineal de estructuras con materiales compuestos. De todos estos modelos se presentan en el artículo unas breves pinceladas, las aplicaciones más relevantes y las referencias donde pueden encontrarse los detalles de cada caso.
Abstract
El artículo es una panorámica de los aspectos teóricos y algunas aplicaciones prácticas de los modelos de fractura desarrollados por diversos grupos [...]
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A finite point method for elasticity problems
E. Oñate, F. Perazzo, J. Canet

(2001). Research Report, Nº PI202

Abstract
The basis of the finite point method (FPM) for the fully meshless solution of elasticity problems in structural mechanics is described. A stabilization technique based on a finite calculus procedure is used to improve the quality of the numerical solution. The efficiency and accuracy of the stabilized FPM in the meshless analysis of simple linear elastic structural problems is shown in some examples of applications.
Abstract
The basis of the finite point method (FPM) for the fully meshless solution of elasticity problems in structural mechanics is described. A stabilization [...]
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Finite element analysis of membrane structures
R. Taylor

(2001). Research Report, Nº PI203

Abstract
This report summarizes the formulation for a large displacement formulation of a membrance composed of three-node triangular elements. A formulation in terms of the deformation gradient is first constructed in terms of nodal variables. In particular, the use of the right Caunchy-Green deformation tensor is shown to lead to a particulary simple representation in terms of nodal quantities. This may then be used to construct general models for use in static and transient analyses.
Abstract
This report summarizes the formulation for a large displacement formulation of a membrance composed of three-node triangular elements. A formulation in terms of the deformation [...]
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On discontinuous Galerkin methods
O. Zienkiewicz, R. Taylor

(2001). Research Report, Nº PI204

Abstract
Discontinuous Galerkin methods have received considerable attention in recent years for applications to many problems in which convection and diffusion terms are present. Several alternatives for treating the diffusion flux effects have been introduced, as well as, for treatment of the convective flux terms. This report summarizes some of the treatments that have been proposed. It also considers how elementary finite volume methods may be considered as the most primative form of a discontinuous Galerkin method as well as how it may be formed as a finite element method. Several numerical examples are included in the report which summarize results for discontinuous Galerkin solutions of one-dimensional problems with a scalar variable. Results are presented for diffusion-reaction problems, convection-diffusion problems, and a special problem with a turning point. We identify aspects which relate to accuracy as well as stability of the method.
Abstract
Discontinuous Galerkin methods have received considerable attention in recent years for applications to many problems in which convection and diffusion terms are present. [...]
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Possibilities of finite calculus in computational mechanics
E. Oñate

(2001). Research Report, Nº PI205

Abstract
The expression ‘finite calculus’ refers to the derivation of the governing differential equations in mechanics by invoking balance of fluxes, forces, etc. in a space–time domain of finite size. The governing equations resulting from this approach are different from those of infinitesimal calculus theory and they incorporate new terms which depend on the dimensions of the balance domain. The new governing equations allow the derivation of naturally stabilized numerical schemes using any discretization procedure. The paper discusses the possibilities of the finite calculus method for the finite element solution of convection–diffusion problems with sharp gradients, incompressible fluid flow and incompressible solid mechanics problems and strain localization situations.
Abstract
The expression ‘finite calculus’ refers to the derivation of the governing differential equations in mechanics by invoking balance of fluxes, forces, etc. in a [...]
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