JOURNALS

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• Ship hydrodynamics

  E. Oñate, J. García-Espinosa, S. Idelsohn

  (2003). Research Report, Nº PI222

  
  

  Abstract

  This chapter presents an overview of some computational methods for analysis of ship hydrodynamics problems. Attention is focused on the description of a stabilized finite element formulation derived via a finite calculus procedure. Both arbitrary Lagrangian-Eulerian (ALE) and fully Lagrangian forms are presented. Details of the treatment of the free-surface waves and the interaction between the ship structure and the sea water are also given. Examples of application to a variety of ship hydrodynamics problems are shown.

  Abstract
  This chapter presents an overview of some computational methods for analysis of ship hydrodynamics problems. Attention is focused on the description of a stabilized finite [...]

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• A general stabilized formulation for incompressible fluid flow using finite calculus and the finite element method

  E. Oñate, J. García-Espinosa, G. Bugeda, S. Idelsohn

  (2003). Research Report, Nº PI223

  
  

  Abstract

  We present a general formulation for incompressible fluid flow analysis using the finite element method (FEM). The necessary stabilization for dealing with convective effects and the incompressibility condition are introduced via the so called finite calculus (FIC) method. The extension of the standard eulerian form of the equations to an arbitrary lagrangian-eulerian (ALE) frame adequate for treating fluid-structure interaction problems is presented. The fully lagrangian form is also discussed. Details of an effective mesh updating procedure are presented together with a method for dealing with free surface effects of importance for ship hydrodynamic analysis and many other fluid flow problems. Examples of application of the eulerian, the ALE and the fully lagrangian flow descriptions are presented.

  Abstract
  We present a general formulation for incompressible fluid flow analysis using the finite element method (FEM). The necessary stabilization for dealing with convective effects [...]

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• Nonlinear dynamic analysis of RC Frame under earthquake loading

  H. Kwak, E. Oñate, S. Kim

  (2003). Research Report, Nº PI229

  
  

  Abstract

  Nonlinear dynamic analysis of a reinforced concrete (RC) frame under earthquake loading is performed in this paper on the basis of a hysteretic moment-curvature relation. Unlike previous analytic moment-curvature relations which take into account the flexural deformation only with the perfect-bond assumption, the proposed relation considers the rigid-body-motion due to anchorage slip at the fixed end, which accounts for more than 50% of the total deformation, using an equivalent flexural stiffness. The advantages of the proposed relation, compared with the layered section approach and multi-component model, may be on the easiness in application to a complex structure composed of many element and on the reduction in calculation time and memory space. The use of curved unloading and reloading branches inferred from the stress-strain relation of steel and consideration of the pinching effect caused by axial force made it possible to describe the structural response more exactly. Finally, correlation studies between analytical and experimental results are conducted to establish the applicability of the proposed model to the nonlinear dynamic analysis of RC structures.

  Abstract
  Nonlinear dynamic analysis of a reinforced concrete (RC) frame under earthquake loading is performed in this paper on the basis of a hysteretic moment-curvature relation. [...]

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• Nodally exact Ritz discretizations of 1D diffusion–absorption and Helmholtz equations by variational FIC and modified equation methods

  C. Felippa, E. Oñate

  (2003). Research Report, Nº PI237

  
  

  Abstract

  This article presents the first application of the Finite Calculus (FIC) in a Ritz-FEM variational framework. FIC provides a steplength parametrization of mesh dimensions, which is used to modify the shape functions. This approach is applied to the FEM discretization of the steady-state, one-dimensional, diffusion–absorption and Helmholtz equations. Parametrized linear shape functions are directly inserted into a FIC functional. The resulting Ritz-FIC equations are symmetric and carry a element-level free parameter coming from the function modification process. Both constant- and variable-coefficient cases are studied. It is shown that the parameter can be used to produce nodally exact solutions for the constant coefficient case. The optimal value is found by matching the finite-order modified differential equation (FOMoDE) of the Ritz-FIC equations with the original field equation. The inclusion of the Ritz-FIC models in the context of templates is examined. This inclusion shows that there is an infinite number of nodally exact models for the constant coefficient case. The ingredients of these methods (FIC, Ritz, MoDE and templates) can be extended to multiple dimensions

  Abstract
  This article presents the first application of the Finite Calculus (FIC) in a Ritz-FEM variational framework. FIC provides a steplength parametrization of mesh dimensions, [...]

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• A finite calculus formulation of the level set equation

  S. Idelsohn, E. Oñate, S. Ransau

  (2003). Research Report, Nº PI239

  
  

  Abstract

  A finite calculus formulation of the level set equation is presented. Quadratic Galerkin finite elements are used for spatial discretization. A unique stabilization parameter is computed. A time stabilization parameter allowing the use of the forward Euler scheme with Courant number larger than one is presetend.

  Abstract
  A finite calculus formulation of the level set equation is presented. Quadratic Galerkin finite elements are used for spatial discretization. A unique stabilization parameter [...]

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• Development of local models and their computational implementation for polymer coated steel sheets

  J. Rojek, M. Luege, E. Oñate

  (2004). Research Report, Nº PI265

  
  

  Abstract

  This report present review of the state of the art of numerical modelling of polymers and polymer coated metal laminates and gives details of selected numerical models including those that will be used in the work in the project POLYCOAT. The first sections studied in the project. Basic mechanical and thermal properties of the polymers are reviewed. Then constitutive models developed for polymers are reviewed based on literature and own work. Details of selected models are given. Deformation behaviour of polymer coated metal laminates is considered with special attention to the phenomena observed at the polymer-metal interface. The numerical models for the interface are presented finally.

  Abstract
  This report present review of the state of the art of numerical modelling of polymers and polymer coated metal laminates and gives details of selected numerical models including [...]

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• El valor del cálculo en los sistemas de ayuda a la toma de decisiones en ingeniería

  E. Oñate

  Revista de Obras Públicas (2004). Vol. 151 (3449), pp. 41-48

  
  

  Abstract

  El artículo revindica el valor de los métodos de cálculo que se enseñan en las Escuelas de Ingeniería, como herramientas indispensables en los nuevos sistemas de ayuda a la toma de decisiones (SAD). Los SAD integran base de datos, métodos de cálculo y módulos de inteligencia artificial, y su utilización se extiende cada día más para ayuda al diseño y gestión de infraestructuras y servicios de ingeniería. En el texto se describen varios desarrollos y aplicaciones recientes de SAD en ingeniería civil. El artículo acaba con una reflexión sobre los límites de los SAD. The paper stresses the value of the computational methods taught in engineering faculties as indispensable tools within the new decision support systems (DSS). The DSS integrate data bases, computational methods and artificial intelligence modules. They are increasingly used for supporting the design and management of civil constructions and services in engineering. The paper describes recent developments and applications of DSS in civil engineering. The text ends up with a discussion on the limits of the DSS. 

  Abstract
  El artículo revindica el valor de los métodos de cálculo que se enseñan en las Escuelas de Ingeniería, como herramientas indispensables [...]

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• Development of a new FEM code for ship hydrodynamics analysis. Applications to the design of America's Cup yachts.

  E. Oñate, J. García-Espinosa

  (2004). Research Report, Nº PI257

  
  

  Abstract

  The objective of the project that is presented at the IV Prize Duran i Farell Award for Research and Technology is the development of a new computational code based on the finite element method for the fluid-dynamics analysis of vessels. The code allows to accurately reproduce the model basin tests (MBT) usually used for the experimental evaluation of the hydrodynamic resistance of ships. The new code, called Tdyn, is a much more economical and precise alternative to model basin tests, by allowing the analysis of the behavior of vessels in real scale, thus eliminating the usual scale errors in the experimental tests. Tdyn incorporates new mathematical models and advanced finite elements methods that have led to numerous international publications. Tdyn was jointly developed by researchers from the Technical University of Catalonia (UPC) of the Department of Strength of Materials and Structural Engineering of the Barcelona School of Civil Engineering and of the Department of Nautical Engineering and Science of the Faculty of Nautical Studies of Barcelona in the framework of several European and national projects carried out in collaboration with the research center CIMNE and the company Compass IS, as well as other prestigious companies in the naval architecture sector. Tdyn was applied to the design of several America’s Cup yachts (in particular, of the ALINGHI team, winner of the 2003 edition). Tdyn is currently commercialized worldwide through Compass IS, a spin-off of the UPC.

  Abstract
  The objective of the project that is presented at the IV Prize Duran i Farell Award for Research and Technology is the development of a new computational code based on the [...]

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• El método de Level Set: Revisión y nuevas propuestas

  A. Valls, J. García-Espinosa, E. Oñate

  (2004). Research Report, Nº PI254

  
  

  Abstract

  El método Level Set utilizado en un amplio espectro de problemas de distinta índole, como la simulación de interfaces entre fluidos, el tratamiento de imágenes, la combustión,…tiene como principal objetivo la simulación numérica de la evolución de interfaces entre distintas regiones en contacto. El presente estudio es una revisión y aportación de nuevas propuestas para el método Level Set, en particular para su aplicación a la interfaz entre fluidos. Este método formulado independiente del tipo de método utilizado para la integración numérica de las ecuaciones en derivadas parciales que gobiernan el fenómeno a simular, disfruta de gran aceptación en el mundo de las diferencias finitas y existe abundante literatura al respecto. En este estudio se ha considerado la combinación del método Level Set y el método de Elementos Finitos no tan usual como en el caso anterior, dotando a este estudio de cierta singularidad. El estudio se ha organizado en 9 secciones o capítulos. En capítulos del 1 al 5 se presenta una introducción teórica al método Level Set con todo el rigor matemático. Se introducen también las últimas ideas desarrolladas en este campo. A lo largo de estos capítulos se propone a modo de ejemplo la aplicación del método Level Set a la interfaz entre dos fluidos. Los capítulos 6 y 7 se presentan los detalles computacionales de este método, así como los detalles de los algoritmos necesarios para la aplicación del método de Level Set. También se hace una revisión de la discretización por el método de los Elementos Finitos estabilizados de la ecuación de transporte, necesaria para la aplicación del método. Los capítulos 8 y 9 recogen varios resultados y conclusiones de la aplicación de este método a distintos ejemplos en dos y tres dimensiones, algunos de ellos presentes en gran parte de la literatura existente.

  Abstract
  El método Level Set utilizado en un amplio espectro de problemas de distinta índole, como la simulación de interfaces entre fluidos, el tratamiento de [...]

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• Economical exploitation of polymer coated steel sheet in large-scale production of new can types by the European can industry

  J. Rojek, E. Oñate, M. Chiumenti, M. Luege, F. Zarate, O. Fruitos, A. Ferriz, S. Oller

  (2004). Research Report, Nº PI252

  
  

  Abstract

  This report presents review of the state of the art of numerical modelling of polymers and polymer coated metal laminates and gives details of selected numerical models including those that will be used in the work in the project POLYCOAT. The first sections of the report contain characteristics of polymers which are important for the application studied in the project. Basic mechanical and thermal properties of the polymers are reviewed. Then constitutive models developed for polymers are reviewed based on literature and own work. Details of selected models are given. Deformation behavior of polymer coated metal laminates is considered with special attention to the phenomena at the polymer-metal interface. The numerical models for the interface are presented finally.  

  Abstract
  This report presents review of the state of the art of numerical modelling of polymers and polymer coated metal laminates and gives details of selected numerical models including [...]

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