Carlos Agelet De Saracibar Bosch (original) (raw)

Papers by Carlos Agelet De Saracibar Bosch

Mecànica de medis continus per a enginyers vol ser una eina per a la formació dels enginyers en l... more Mecànica de medis continus per a enginyers vol ser una eina per a la formació dels enginyers en la mecànica dels medis continus, que manté un equilibri adequat entre el rigor del seu plantejament i la claredat dels principis físics que aborda. El contingut es divideix en dues parts ben diferenciades, que es presenten seqüencialment. A la primera part -capítols de 1 al 5-, s’introdueixen els aspectes fonamentals i descriptius comuns de tots els medis continus (moviment, deformació, tensió i equacions de conservació-balanç). A la segona part -capítols del 6 a 11-, s’estudien famílies específiques de medis continus, com ara els sòlids i els fluids, en un plantejament que s’inicia amb l’equació constitutiva corresponent i conclou amb les formulacions clàssiques de la mecànica de sòlids (elàstics lineals i elastoplàstics) i de la mecànica de fluids (règim laminar). Finalment, es fa una incursió breu en els principis variacionals (principis dels treballs virtuals i de minimització de l’en...

Nuclear Espana (1996), 2014

Revista Internacional De Metodos Numericos Para Calculo Y Diseno En Ingenieria, Oct 1, 2005

Revista Internacional De Metodos Numericos Para Calculo Y Diseno En Ingenieria, 2006

Se presenta una formulación en multiescalas del método de elementos finitos capaz de estabilizar ... more Se presenta una formulación en multiescalas del método de elementos finitos capaz de estabilizar el comportamiento de elementos mixtos en problemas de elasticidad y de plasticidad incompresibles en grandes deformaciones. Esta formulación se fundamenta en el concepto de las sub-escalas ortogonales (OSGS) y se aplica a elementos triangulares y tetraédricos mixtos, con interpolaciones de desplazamientos y presión continuas. La formulación permite eludir la condición de estabilidad de Babuska-Brezzi, y ofrece como principal ventaja la posibilidad de utilizar interpolaciones lineales en elementos mixtos triangulares y tetraédricos, muy convenientes en aplicaciones de interés práctico debido a su versatilidad para la generación de mallas sobre configuraciones geométricas complejas. Se explican tanto las consideraciones empleadas en el planteamiento, como los principales aspectos de implementación. Una de las contribuciones más relevantes de esta formulación es la eficacia y originalidad de la aproximación propuesta para el parámetro de estabilización. Finalmente, mediante ejemplos de simulación se muestra el buen comportamiento de los elementos obtenidos en comparación con elementos estándar y Q1P0.

El objetivo de este trabajo es el modelado de la disolución de precipitados con endurecimiento y ... more El objetivo de este trabajo es el modelado de la disolución de precipitados con endurecimiento y evolución de la dureza para aleaciones de aluminio en procesos de soldadura por batido y fricción y/o procesos de tratamientos térmicos. El modelo utilizado toma como punto de partida el modelo propuesto por Myhr y Grong (1991), basado en la cinética de la disolución de precipitados con endurecimiento para aleaciones de aluminio. Este modelo contiene una única variable independiente, el tiempo, y una única variable de estado, la fracción volumétrica de precipitados. Puntos cruciales del modelo son la identificación de la energía de activación efectiva para la disolución de precipitados con endurecimiento y la obtención de la denominada curva maestra que define el modelo y viene dada en forma de tabla. El objetivo de este trabajo es obtener una estimación de la energía de activación efectiva y modelar la tasa de disolución de precipitados por unidad de tiempo en aleaciones de aluminio con...

Archive of Applied Mechanics, 2020

A stabilized finite element formulation is proposed to the study of the finite deformation of a p... more A stabilized finite element formulation is proposed to the study of the finite deformation of a porous solid saturated with a compressible fluid. Unlike previous finite element schemes, the compressibility of the fluid constituent is entirely considered, and particularly, the a porosity-dependent permeability is utilized in the present formulation. As a special case, the formulation for the saturating fluid being an ideal gas is also derived. The displacement of solid skeleton and pore pressure are treated as primary variables to express the resulting coupled nonlinear system of equations. Equal-order C 0 elements are employed to approximate displacement and pressure fields. The stability problem caused by the equal-order interpolation is overcome by using the method of polynomial pressure projections. Two examples are provided to demonstrate the effect of fluid compressibility, as well as the porosity-dependent permeability, on the responses of the material.

As one of the results of an ambitious project, this handbook provides a well-structured directory... more As one of the results of an ambitious project, this handbook provides a well-structured directory of globally available software tools in the area of Integrated Computational Materials Engineering (ICME). The compilation covers models, software tools, and numerical methods allowing describing electronic, atomistic, and mesoscopic phenomena, which in their combination determine the microstructure and the properties of materials. It reaches out to simulations of component manufacture comprising primary shaping, forming, joining, coating, heat treatment, and machining processes. Models and tools addressing the in-service behavior like fatigue, corrosion, and eventually recycling complete the compilation. An introductory overview is provided for each of these different modelling areas highlighting the relevant phenomena and also discussing the current state for the different simulation approaches. A must-have for researchers, application engineers, and simulation software providers seeking a holistic overview about the current state of the art in a huge variety of modelling topics. This handbook equally serves as a reference manual for academic and commercial software developers and providers, for industrial users of simulation software, and for decision makers seeking to optimize their production by simulations. In view of its sound introductions into the different fields of materials physics, materials chemistry, materials engineering and materials processing it also serves as a tutorial for students in the emerging discipline of ICME, which requires a broad view on things and at least a basic education in adjacent fields.Postprint (published version

Cauce 2000 Revista De La Ingenieria Civil, 2001

AIP Conference Proceedings, 2010

In this paper a computational model for the numerical simulation of Friction Stir Welding (FSW) p... more In this paper a computational model for the numerical simulation of Friction Stir Welding (FSW) processes is presented. FSW is a new method of welding in solid state in which a shouldered tool with a profile probe is rotated and slowly plunged into the joint line between two pieces of sheet or plate material which are butted together. Once the

International Journal of Materials Research, 2010

Abstract In this paper an integrated model has been utilized to predict thermo-mechanical behavio... more Abstract In this paper an integrated model has been utilized to predict thermo-mechanical behavior during friction stir welding of an aluminum alloy. A finite element code, ABAQUS, is employed to solve the governing equations of heat conduction and plastic deformation, while a rigid – viscoplastic material behavior is utilized and effects of different thermal and mechanical boundary conditions are considered in the simulation. To assess the accuracy of the model, predicted results have been compared with experimental data and good agreement has been observed.

This book was born with the vocation of being a tool for the training of engineers in continuum m... more This book was born with the vocation of being a tool for the training of engineers in continuum mechanics. In fact, it is the fruit of the experience in teaching this discipline during many years at the Civil Engineering School of the Technical University of Catalonia (UPC/BarcelonaTech), both in undergraduate degrees (Civil Engineering and Geological Engineering) and postgraduate degrees (Master and PhD courses). Unlike other introductory texts to the mechanics of continuous media, the work presented here is specifically aimed at engineering students. We try to maintain a proper balance between the rigor of the mathematical formulation used and the clarity of the physical principles addressed, although always putting the former at the service of the latter. In this sense, the essential vector and tensor operations use simultaneously the indicial notation (more useful for rigorous mathematical proof) and the compact notation (which allows for a better understanding of the physics of...

This paper deals with the numerical simulation of Friction Stir Welding (FSW) processes. FSW tech... more This paper deals with the numerical simulation of Friction Stir Welding (FSW) processes. FSW techniques are used in many industrial applications and particularly in the aeronautic and aerospace industries, where the quality of the joining is of essential importance. The analysis is focused either at global level, considering the full component to be jointed, or locally, studying more in detail the heat a¤ected zone (HAZ). The analysis at global (structural component) level is performed de…ning the problem in the Lagrangian setting while, at local level, an apropos kinematic framework which makes use of an e¢ cient combination of Lagrangian (pin), Eulerian (metal sheet) and ALE (stirring zone) descriptions for the di¤erent computational sub-domains is introduced for the numerical modeling. As a result, the analysis can deal with complex (non-cylindrical) pin-shapes and the extremely large deformation of the material at the HAZ without requiring any remeshing or remapping tools. A fully coupled thermo-mechanical framework is proposed for the computational modeling of the FSW processes proposed both at local and global level. A staggered algorithm based on an isothermal fractional step method is introduced. To account for the isochoric behavior of the material when the temperature range is close to the melting point or due to the predominant deviatoric deformations induced by the visco-plastic response, a mixed …nite element technology is introduced. The Variational Multi Scale (VMS) method is used to circumvent the LBB stability condition allowing the use of linear/linear P1/P1 interpolations for displacement (or velocity, ALE/Eulerian formulation) and pressure …elds, respectively. The same stabilization strategy is adopted to tackle the instabilities of the temperature …eld, inherent characteristic of convective dominated problems (thermal analysis in ALE/Eulerian kinematic framework). At global level, the material behavior is characterized by a thermo-elasto-viscoplastic constitutive model. The analysis at local level is characterized by a rigid thermo-visco-plastic constitutive model. Di¤erent thermally coupled (non-Newtonian) ‡uid-like models as Norton-Ho¤, Carreau or Sheppard-Wright, among others are tested. To better understand the material ‡ow pattern in the stirring zone, a (Lagrangian based) particle tracing is carried out while post-processing FSW results. A coupling strategy between the analysis of the process zone nearby the pin-tool (local level analysis) and the simulation carried out for the entire structure to be welded (global level analysis) is implemented to accurately predict the temperature histories and, thereby, the residual stresses in FSW.

Fusion Engineering and Design, 2018

The objective of ITER is to build a new Tokamak, with the goal of demonstrating the scientific an... more The objective of ITER is to build a new Tokamak, with the goal of demonstrating the scientific and technical feasibility of fusion power. The First Wall Panels are the inner component of the reactor, built with different materials that must support high heat flux levels inside the vacuum vessel. The manufacturing processes of the First Wall are a complex procedure including bending, hipping and cutting procedures which, in general, lead to residual stresses and distortions of the fabricated component. In this work, the analysis of the thermo-mechanical response of a simplified prototype of the ITER NHF First Wall Panel is presented from the numerical point of view. The experimental procedure within each phase of the whole manufacturing process is described. Residual stresses and distortions have been measured and analyzed. The numerical simulation of the manufacturing process includes the description of the main hypothesis, the applied loads and the boundary conditions assumed at every stage of the process. Special attention is paid to the simulation of machining and cutting by means of an adhoc element deactivation strategy. The numerical results are compared with the experimental evidence to show the prediction capability and the limitations of the proposed numerical model.

Metals, 2019

The computational modeling and numerical simulation of Friction Stir Welding (FSW) processes is a... more The computational modeling and numerical simulation of Friction Stir Welding (FSW) processes is an extremely challenging task due to the highly nonlinear and coupled nature of the physical problem and the complex computational issues that need to be properly tackled in the numerical model [...]

International Journal for Numerical Methods in Engineering, 2017

SummaryIn this paper, conserving time‐stepping algorithms for frictionless and full stick frictio... more SummaryIn this paper, conserving time‐stepping algorithms for frictionless and full stick friction dynamic contact problems are presented. Time integration algorithms for frictionless and full stick friction dynamic contact problems have been designed to preserve the conservation of key discrete properties satisfied at the continuum level. Energy and energy‐momentum–preserving algorithms for frictionless and full stick friction dynamic contact problems, respectively, have been designed and implemented within the framework of the direct elimination method, avoiding the drawbacks linked to the use of penalty‐based or Lagrange multipliers methods. An assessment of the performance of the resulting formulation is shown in a number of selected and representative numerical examples, under full stick friction and slip frictionless contact conditions. Conservation of key discrete properties exhibited by the time‐stepping algorithm is shown.

International Journal of Mechanical Sciences, 2017

Pin geometry is a fundamental consideration in friction stir welding (FSW). It influences the the... more Pin geometry is a fundamental consideration in friction stir welding (FSW). It influences the thermal behaviour, material flow and forces during the weld and reflects on the joint quality. This work studies four pin tools with circular, triflute, trivex, and triangular profiles adopting a validated model of FSW process developed by the authors. The effect of the rotating tool geometry on the flow behaviour and process outcomes is analysed. Additionally, longitudinal and transversal forces and torque are numerically calculated and compared for the different pin shapes. The study is carried out for slip and stick limiting friction cases between pin and workpiece. The main novelties of the paper are a "speed-up" two-stage simulation methodology and a piecewise linear version of the constitutive model, both of them conceived for the use in real case industrial applications, where the achievement of accuracy with affordable simulation times is of importance. The Norton-Hoff constitutive model is adopted to characterize the material behaviour during the weld. The piecewise linear version of the model developed by the authors greatly facilitates the convergence of the numerical solution ensuring both computational efficiency and accuracy. A two-stage computational procedure is applied. In the first stage, a forced transient is carried out; in the second one, the magnitudes of interest are computed. The study shows that the proposed modelling approach can be used to predict and interpret the FSW behaviour for a specific pin geometry. Moreover, the reduction of the simulation time using the two-stage strategy can be up to 90%, compared to a standard single stage strategy.

Finite Elements in Analysis and Design, 2016

Electron Beam Welding (EBW) is a highly efficient and precise welding method increasingly used wi... more Electron Beam Welding (EBW) is a highly efficient and precise welding method increasingly used within the manufacturing chain and of growing importance in different industrial environments such as the aeronautical and aerospace sectors. This is because, compared to other welding processes, EBW induces lower distortions and residual stresses due to the lower and more focused heat input along the welding line. This work describes the formulation adopted for the numerical simulation of the EBW process as well as the experimental work carried out to calibrate and validate it. The numerical simulation of EBW involves the interaction of thermal, mechanical and metallurgical phenomena. For this reason, in this work the numerical framework couples the heat transfer process to the stress analysis to maximize accuracy. An in-house multi-physics FE software is used to deal with the numerical simulation. The definition of an ad hoc moving heat source is proposed to simulate the EB power surface distribution and the corresponding absorption within the work-piece thickness. Both heat conduction and heat radiation models are considered to dissipate the heat through the boundaries of the component. The material behavior is characterized by an apropos thermo-elasto-viscoplastic constitutive model. Titanium-alloy Ti6A14V is the target material of this work. From the experimental side, the EB welding machine, the vacuum chamber characteristics and the corresponding operative setting are detailed. Finally, the available facilities to record the temperature evolution at different thermo-couple locations as well as to measure both distortions and residual stresses are described. Numerical results are compared with the experimental evidence.

The International Journal of Advanced Manufacturing Technology, 2016

This work describes the local-global strategy proposed for the computation of residual stresses i... more This work describes the local-global strategy proposed for the computation of residual stresses in Friction Stir Welding (FSW) processes. A coupling strategy between the analysis of the process zone nearby the pin-tool (local level analysis) and the simulation carried out for the entire structure to be welded (global level analysis) is implemented to accurately predict the temperature histories and, thereby, the residual stresses in FSW. As a first step, the local problem solves the material stirring as well as the heat generation induced by the pin and shoulder rotation at the heat affected zone. The Arbitrary Lagrangian Eulerian (ALE) formulation is adopted to deal with the rotation of complex pin shapes. A thermo-rigid-viscoplastic constitutive law is employed to characterize the viscous flow of the material, driven by the high strain rates induced by the FSW process. A mixed temperaturevelocity-pressure finite element technology is used to deal with the isochoric nature of the the strains. The output of this local analysis is the heat generated either by plastic dissipation or by friction and it is used as the power input for the welding analysis at structural (global) level. The global problem is tackled within the Lagrangian framework together with a thermoelasto-viscoplastic constitutive model. Also in this case the mixed temperature-displacement-2 pressure format is introduced to deal with the deviatoric nature of the plastic strains. The outcomes of this analysis are the distortions and the residual stresses after welding. The material used in this work is stainless steel 304L; however, the methodology presented is applicable to a wide range of materials. The proposed numerical strategy is validated by the experimental evidence.

Advances in Materials and Processing Technologies, 2015

Friction Stir Welding (FSW) process is a relatively recent welding process (patented in 1991). FS... more Friction Stir Welding (FSW) process is a relatively recent welding process (patented in 1991). FSW is a solid-state joining process during which materials to be joined are not melted. During the FSW process, the behaviour of the material is at the interface between solid mechanics and fluid mechanics. In this paper, a 3D numerical model of the FSW process with a non-cylindrical tool based on a solid formulation is compared to another one based on a fluid formulation. Both models use advanced numerical techniques such as the Arbitrary Lagrangian Eulerian (ALE) formulation, remeshing or the Orthogonal Sub-Grid Scale method (OSS). It is shown that these two formulations essentially deliver the same results.

JOM, 2015

The Integrated Computational Materials Engineering expert group (ICMEg), a coordination activity ... more The Integrated Computational Materials Engineering expert group (ICMEg), a coordination activity of the European Commission, aims at developing a global and open standard for information exchange between the heterogeneous varieties of numerous simulation tools. The ICMEg consortium coordinates respective developments by a strategy of networking stakeholders in the first International Workshop on Software Solutions for ICME, compiling identified and relevant software tools into the Handbook of Software Solutions for ICME, discussing strategies for interoperability between different software tools during a second (planned) international workshop, and eventually proposing a scheme for standardized information exchange in a future book or document. The present article summarizes these respective actions to provide the ICME community with some additional insights and resources from which to help move this field forward.