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• Performance of mixed formulations for the particle finite element method in soil mechanics problems

  L. Monforte, J. Puigbó, M. Arroyo, A. Gens

  Comp. Part. Mech (2016). (Preprint) Vol. 4 (3), pp. 269-284

  
  

  Abstract

  This paper presents a computational framework for the numerical analysis of fluid-saturated porous media at large strains. The proposal relies, on one hand, on the particle finite element method (PFEM), known for its capability to tackle large deformations and rapid changing boundaries, and, on the other hand, on constitutive descriptions well established in current geotechnical analyses (Darcy’s law; Modified Cam Clay; Houlsby hyperelasticity). An important feature of this kind of problem is that incompressibility may arise either from undrained conditions or as a consequence of material behaviour; incompressibility may lead to volumetric locking of the low-order elements that are typically used in PFEM. In this work, two different three-field mixed formulations for the coupled hydromechanical problem are presented, in which either the effective pressure or the Jacobian are considered as nodal variables, in addition to the solid skeleton displacement and water pressure. Additionally, several mixed formulations are described for the simplified single-phase problem due to its formal similitude to the poromechanical case and its relevance in geotechnics, since it may approximate the saturated soil behaviour under undrained conditions. In order to use equal-order interpolants in displacements and scalar fields, stabilization techniques are used in the mass conservation equation of the biphasic medium and in the rest of scalar equations. Finally, all mixed formulations are assessed in some benchmark problems and their performances are compared. It is found that mixed formulations that have the Jacobian as a nodal variable perform better.

  Abstract
  This paper presents a computational framework for the numerical analysis of fluid-saturated porous media at large strains. The proposal relies, on one hand, on the particle [...]

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• Continuous chip formation in metal cutting processes using the Particle Finite Element Method (PFEM)

  J. Rodríguez, J. Puigbó, J. Cante, J. Oliver

  Int. J. Solids and Structures (2017). Vol. 120, pp. 81-120

  
  

  Abstract

  This paper presents a study on the metal cutting simulation with a particular numerical technique, the Particle Finite Element Method (PFEM) with a new modified time integration algorithm and incorporating a contact algorithm capability . The goal is to reproduce the formation of continuous chip in orthogonal machining. The paper tells how metal cutting processes can be modelled with the PFEM and which new tools have been developed to provide the proper capabilities for a successful modelling. The developed method allows for the treatment of large deformations and heat conduction, workpiece-tool contact including friction effects as well as the full thermo-mechanical coupling for contact. The difficulties associated with the distortion of the mesh in areas with high deformation are solved introducing new improvements in the continuous Delaunay triangulation of the particles. The employment of adaptative insertion and removal of particles at every new updated configuration improves the mesh quality allowing for resolution of finer-scale features of the solution. The performance of the method is studied with a set of different two-dimensional tests of orthogonal machining. The examples consider, from the most simple case to the most complex case, different assumptions for the cutting conditions and different material properties. The results have been compared with experimental tests showing a good competitiveness of the PFEM in comparison with other available simulation tools.

  Abstract
  This paper presents a study on the metal cutting simulation with a particular numerical technique, the Particle Finite Element Method (PFEM) with a new modified time integration [...]

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• Generation of segmental chips in metal cutting modeled with the PFEM

  J. Prieto, J. Puigbó, J. Cante, J. Oliver, P. Jonsén

  Computational Mechanics (2018). Vol. 61 (6), pp. 639-655

  
  

  Abstract

  The Particle Finite Element Method, a lagrangian finite element method based on a continuous Delaunay re-triangulation of the domain, is used to study machining of Ti6Al4V. In this work the method is revised and applied to study the influence of the cutting speed on the cutting force and the chip formation process. A parametric methodology for the detection and treatment of the rigid tool contact is presented. The adaptive insertion and removal of particles are developed and employed in order to sidestep the difficulties associated with mesh distortion, shear localization as well as for resolving the fine-scale features of the solution. The performance of PFEM is studied with a set of different two-dimensional orthogonal cutting tests. It is shown that, despite its Lagrangian nature, the proposed combined finite element-particle method is well suited for large deformation metal cutting problems with continuous chip and serrated chip formation.

  Abstract
  The Particle Finite Element Method, a lagrangian finite element method based on a continuous Delaunay re-triangulation of the domain, is used to study machining [...]

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• Coupled effective stress analysis of insertion problems in geotechnics with the Particle Finite Element Method

  L. Monforte, M. Arroyo, J. Puigbó, A. Gens

  Computers and Geotechnics (2018). Vol. 101, pp. 114-129

  
  

  Abstract

  This paper describes a computational framework for the numerical analysis of quasi-static soil-structure insertion problems in water saturated media. The Particle Finite Element Method is used to solve the linear momentum and mass balance equations at large strains. Solid-fluid interaction is described by a simplified Biot formulation using pore pressure and skeleton displacements as basic field variables. The robustness and accuracy of the proposal is numerically demonstrated presenting results from two benchmark examples. The first one addresses the consolidation of a circular footing on a poroelastic soil. The second one is a parametric analysis of the cone penetration test (CPTu) in a material described by a Cam-clay hyperelastic model, in which the influence of permeability and contact roughness on test results is assessed.

  Abstract
  This paper describes a computational framework for the numerical analysis of quasi-static soil-structure insertion problems in water saturated media. The Particle Finite [...]

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• Hydraulic conductivity from piezocone on-the-fly: a numerical evaluation

  L. Monforte, M. Arroyo, A. Gens, J. Puigbó

  Géotechnique Letters (2018). Vol. 8 (4), pp. 268-277

  
  

  Abstract

  Permeability is important in many geotechnical applications. The current (cone penetration test that gathers piezometer data (CPTu)) practice to obtain permeability values relies on dissipation tests, which are frequently slow and only linked to permeability through compressibility measures. On-the-fly methods offer an alternative approach in which permeability is directly linked to CPTu penetration measurements. Several on-the-fly methods have been proposed and their applicability and relative advantages are not fully clear. Numerical effective stress simulation of CPTu testing is used here to explore in a simplified but realistic setting the relative merits of different on-the-fly methods. It is found that for partly drained materials, the original simpler relation between cone metrics and normalised permeability works reasonably well. A continuous generalisation of Elsworth and Lee method to the full permeability range is proposed, noting the connection to the backbone normalised pore-pressure curve that describes the partly drained transition of cone penetration. The importance of an undrained limit beyond which the method produces large errors is emphasised.

  Abstract
  Permeability is important in many geotechnical applications. The current (cone penetration test that gathers piezometer data (CPTu)) practice to obtain permeability values [...]

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• Numerical Methods for the Modelling of Chip Formation

  J. Prieto, J. Puigbó, P. Jonsén

  Archives of Comp. Meths. Engng. (2018). Epub ahead of print

  
  

  Abstract

  The modeling of metal cutting has proved to be particularly complex due to the diversity of physical phenomena involved, including thermo-mechanical coupling, contact/friction and material failure. During the last few decades, there has been significant progress in the development of numerical methods for modeling machining operations. Furthermore, the most relevant techniques have been implemented in the relevant commercial codes creating tools for the engineers working in the design of processes and cutting devices. This paper presents a review on the numerical modeling methods and techniques used for the simulation of machining processes. The main purpose is to identify the strengths and weaknesses of each method and strategy developed up-to-now. Moreover the review covers the classical Finite Element Method covering mesh-less methods, particle-based methods and different possibilities of Eulerian and Lagrangian approaches.

  Abstract
  The modeling of metal cutting has proved to be particularly complex due to the diversity of physical phenomena involved, including thermo-mechanical coupling, contact/friction [...]

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• Low‐order stabilized finite element for the full Biot formulation in soil mechanics at finite strain

  L. Monforte, P. Navas, J. Puigbó, M. Arroyo, A. Gens

  International Journal for Numerical and Analytical Methods in Geomechanics (2019). Vol. 43 (7), pp. 1488-1515

  
  

  Abstract

  This article presents a novel finite element formulation for the Biot equation using low‐order elements. Additionally, an extra degree of freedom is introduced to treat the volumetric locking steaming from the effective response of the medium; its balance equation is also stabilized. The accuracy of the proposed formulation is demonstrated by means of numerical analyses.

  Abstract
  This article presents a novel finite element formulation for the Biot equation using low‐order elements. Additionally, an extra degree of freedom is introduced to treat [...]

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• Reply to the Discussion on “Coupled effective stress analysis of insertion problems in geotechnics with the Particle Finite Element method”

  L. Monforte, M. Arroyo, J. Puigbó, A. Gens

  Computers and Geotechnics (2019). Vol. 109, pp. 209-292

  
  

  Abstract

  The discussers ask why a hyperelastic model was employed. There are several reasons why using an hyper-elastic model is preferable. Probably the most important one is that closed cycles do not produce nor dissipate energy [17, 8]; instead, using a hypoelastic model, closed cycles may produce or dissipate energy, which is inconsistent with the definition of an elastic deformation path. As stressed by Borja et al.[3], the use of an hypoelastic law with constant Poisson’s ratio in the context of the Modified Cam Clay may produce that closed-loop stress paths may result in a non-conservative elastic behavior; therefore, at the end of the loading path the elastic deformation might not be fully recovered. Also, hyper-elastic laws underpin the formulation of large-strain elastoplasticity [17]. By using this theory, the constitutive model is inherently frame-indiferent [17] and algorithmic objective [9].

  Abstract
  The discussers ask why a hyperelastic model was employed. There are several reasons why using an hyper-elastic model is preferable. Probably the most important one is that [...]

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• A stable mesh-independent approach for numerical modelling of structured soils at large strains

  L. Monforte, M. Ciantia, J. Puigbó, M. Arroyo, A. Gens

  Computers and Geotechnics (2019). Vol. 116, pp. 103215-1/103215-14

  
  

  Abstract

  We describe the large strain implementation of an elasto-plastic model for structured soils into G-PFEM, a code developed for geotechnical simulations using the Particle Finite Element Method. The constitutive model is appropriate for naturally structured clays, cement-improved soils and soft rocks. Structure may result in brittle behavior even in contractive paths; as a result, localized failure modes are expected in most applications. To avoid the pathological mesh-dependence that may accompany strain localization, a nonlocal reformulation of the model is employed. The resulting constitutive model is incorporated into a numerical code by means of a local explicit stress integration technique. To ensure computability this is hosted within a more general Implicit-Explicit integration scheme (IMPLEX). The good performance of these techniques is illustrated by means of element tests and boundary value problems.

  Abstract
  We describe the large strain implementation of an elasto-plastic model for structured soils into G-PFEM, a code developed for geotechnical simulations using the Particle Finite [...]

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• Advances in the DEM and coupled DEM and FEM techniques in non linear solid mechanics

  E. Oñate, F. Zárate, M. Celigueta, J. González, J. Canet, J. Puigbó, F. Garcia, S. Latorre, M. Santasusana

  (2018). (Preprint) Advances in Computational Plasticity. Computational Methods in Applied Sciences. Oñate, E., Peric, D., de Souza Neto, E., Chiumenti, M., (Eds.), Vol. 46, pp. 309-335, Springer

  
  

  Abstract

  In this chapter we present recent advances on the Discrete Element Method (DEM) and on the coupling of the DEM with the Finite Element Method (FEM) for solving a variety of problems in non linear solid mechanics involving damage, plasticity and multifracture situations.

  Abstract
  In this chapter we present recent advances on the Discrete Element Method (DEM) and on the coupling of the DEM with the Finite Element Method (FEM) for solving a variety of [...]

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Articles (Documents not available in Scipedia)

• Generation of segmental chips in metal cutting modeled with the PFEM

  JMR Prieto, JM Carbonell, JC Cante, J Oliver, P Jonsén

  Computational Mechanics, 1-17, 2017

• Continuous chip formation in metal cutting processes using the Particle Finite Element Method (PFEM)

  JM Rodríguez, JM Carbonell, JC Cante, J Oliver

  International Journal of Solids and Structures 120, 81-102, 2017

• PFEM formulation for thermo-coupled FSI analysis. Application to nuclear core melt accident

  A Franci, E Oñate, JM Carbonell, M Chiumenti

  Computer Methods in Applied Mechanics and Engineering 325, 711-732, 2017

• Performance of mixed formulations for the particle finite element method in soil mechanics problems

  L Monforte, JM Carbonell, M Arroyo, A Gens

  Computational Particle Mechanics 4 (3), 269-284, 2017

• Damage analysis of masonry structures subjected to rockfalls

  O Mavrouli, PG Giannopoulos, JM Carbonell, C Syrmakezis

  Landslides 14 (3), 891-904, 2017

• Numerical simulation of undrained insertion problems in geotechnical engineering with the Particle Finite Element Method (PFEM)

  L Monforte, M Arroyo, JM Carbonell, A Gens

  Computers and Geotechnics 82, 144-156, 2017

• Simulation of the cone penetration test: discrete and continuum approaches

  A Gens Solé, M Arroyo Alvarez de Toledo, J Butlanska, L Monforte Vila, ...

  Geotechnical and geophysical site characterisation 5: Proceedings of the …, 2016

• Simulation of the cone penetration test: discrete and continuum approaches

  A Gens, M Arroyo, J Butlanska, JM Carbonell, M Ciantia, L Monforte, ...

  Aust. Geomech 51 (4), 169-182, 2016

• Velocity‐based formulations for standard and quasi‐incompressible hypoelastic‐plastic solids

  A Franci, E Oñate, JM Carbonell

  International Journal for Numerical Methods in Engineering 107 (11), 970-990, 2016

• The Double Hierarchy Method. A parallel 3D contact method for the interaction of spherical particles with rigid FE boundaries using the DEM

  M Santasusana, J Irazábal, E Oñate, JM Carbonell

  Computational Particle Mechanics 3 (3), 407-428, 2016

• The particle finite element method (PFEM) in thermo‐mechanical problems

  JM Rodriguez, JM Carbonell, JC Cante, J Oliver

  International Journal for Numerical Methods in Engineering 107 (9), 733-785, 2016

• Numerical simulation of penetration problems in geotechnical engineering with the particle finite element method (PFEM)

  L Monforte Vila, JM Carbonell Puigbó, M Arroyo Alvarez de Toledo, ...

  Proceedings of the IV International Conference on Particle-Based Methods …, 2015

• Explicit finite deformation stress integration of the elasto-plastic constitutive equations

  L Monforte, M Arroyo, A Gens, JM Carbonell

  Computer Methods and Advances in Geomechanics, 267-272, 2015

• On the effect of the bulk tangent matrix in partitioned solution schemes for nearly incompressible fluids

  A Franci, E Oñate, JM Carbonell

  International Journal for Numerical Methods in Engineering 102 (3-4), 257-277, 2015

• Evaluation of multilayer pavement viscoelastic properties from falling weight deflectometer using neural networks

  JM Gonzalez, JM Carbonell, W van Bijsterveld

  Materials and Infrastructures 1, 211-225, 2014

• A particle finite element method (PFEM) for coupled thermal analysis of quasi and fully incompressible flows and fluid-structure interaction problems

  E Oñate, A Franci, JM Carbonell

  Numerical Simulations of Coupled Problems in Engineering, 129-156, 2014

• On the effect of the tangent bulk stiffness matrix in the analysis of free surface Lagrangian flows using PFEM

  A Franci, E Oñate, JM Carbonell

  Research Report CIMNE PI402, 2013

• Modelling of tunnelling processes and rock cutting tool wear with the particle finite element method

  JM Carbonell, E Oñate, B Suárez

  Computational Mechanics 52 (3), 607-629, 2013

• Advances in the particle finite element method (PFEM) for solving coupled problems in engineering

  E Oñate, SR Idelsohn, MA Celigueta, R Rossi, J Marti, JM Carbonell, ...

  Particle-Based Methods, 1-49, 2011

• Análisis numérico de los fenómenos hidrodinámicos en escolleras con aplicaciones a presas de materiales sueltos

  RJ Hernández, E Oñate, SR Idelsohn, MA Celigüeta, R Rossi, J Marti, ...

  Universitat Politècnica de Catalunya. Escola Tècnica Superior d'Enginyers de …, 2010

• Modeling of surface wear by the particle finite element method: application to tunneling processes

  JM Carbonell Puigbó, B Suárez Arroyo, E Oñate Ibáñez de Navarra

  Computational Plasticity X-Fundamentals and Applications, 1-4, 2009