COLLECTIONS

Documents published in Scipedia

• On the usage of augmented reality in hepatic oncosurgery

  O. Palomares, E. Soudah, O. Coss, I. Valero, J. Pavía

  Monograph CIMNE (2018). M183

  
  

  Abstract

  Half of all patients diagnosed with colorectal cancer develop liver metastasis during the course of their disease. Surgery provides the best opportunity for long-term survival and even the chance for cure. In order to achieve an adequate tumor resection, the surgeon must have precise knowledge of the tumor location relative to the surrounding major vascular structures. However, in order to do so, current surgeons have to continually look away from the patient to see the patient CT scan or MRI on a nearby monitor. Thus, there is then a clinical need for a better system that can assist surgeons. In this project, the feasibility of using augmented reality (AR) to assist open liver surgeries was studied. Separate volumes of liver surface, vascular and tumor structures were delineated from an animal's liver CT scan. These were then 3D printed and further rendered by means of a custom application within the HoloLens™ head-mounted display. The accuracy of image registration was subjectively evaluated by checking the alignment of the visible structures between the virtual model and the 3D printed model. By using a combination of tracked hand gestures and voice commands, the AR setup developed successfully indicated with high accuracy the location of the tumor and vasculature of the liver model. These significant results suggest that the superimposition of structures onto the patient liver could facilitate the orientation and navigation during a surgery. This would result in the improvement of tumor resection, leading to an increasing patient safety.

  Abstract
  Half of all patients diagnosed with colorectal cancer develop liver metastasis during the course of their disease. Surgery provides the best opportunity for long-term survival [...]

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• Discrete Volume Method. A variational approach for brittle fracture

  V. Cardoso, E. Oñate, S. Botello

  Monograph CIMNE (2019). M184

  
  

  Abstract

  The Discrete Element Method has been used to simulate fracture dynamics beacuse its inherent capacity to reproduce multi-body interaction, but in the case of elasticity mechanics the microparameters of the numerical model, required to replicate the properties of the material, are difficult to calibrate. On the other hand, damage models based on finite element strategies can easily reproduce the properties of the media but they can not simulate the dynamics of multiple fractures. We propose a numerical approach, the Discrete Volume Method, to simulate fracture of brittle materials without the disadvantages mentioned, by combining the benefits of variational formulations and the numerical convenience of discrete element method to capture the dynamics of cracks. The Discrete Volume Method does not have microparameters, since the displacements are computed using the material properties and the fracture mechanism is controlled by an auxiliary damage field. Within this work we discuss a numerical strategy to solve the elasticity problem upon unstructured and non conforming meshes, allowing all kinds of flat-faced elements (polygons in 2D and polyhedra in 3D). The core of the formulation relies on two numerical procedures the Control Volume Function Approximation (CVFA), and the polynomial interpolation in the neighborhood of the control volumes, which is used to solve the surface integrals resulting from applying the divergence theorem. By comparing the estimated stress against the analytical stress field of the well known test of an infinite plate with a hole, we show that this conservative approach is robust and accurate. A similar strategy is used to get the damage field solution. In order to coupling both fields, displacement and damage, we use a finite increment arrangement for reducing the resdidual of elastic equation within each time step. We develop a numerical formulation for time discretization based on the analytical solution of the differential equation resulting from assuming a continuous variation of internal forces of the system between time steps. Finally, we show the effectiveness of the methodology by performing numerical experiments and comparing the solutions with published results. 

  Abstract
  The Discrete Element Method has been used to simulate fracture dynamics beacuse its inherent capacity to reproduce multi-body interaction, but in the case of elasticity mechanics [...]

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• Ship hydrodynamics

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

  (2004). Encyclopedia of Computational Mechanics, E. Stein, R. de Borst and T.J.R. Hughes (Eds.), John Wiley & Sons Ltd, Vol. 3, Chapter 18, pp. 579 - 607

  
  

  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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• Meshless analysis of incompressible flows using the Finite Point Method

  E. Oñate, C. Sacco, S. Idelsohn

  (2001). Innovative Tools for Scientific Computation in Aeronautical Engineering, J. Periaux, P. Joly, O. Pironneau and E. Oñate (Eds.), pp. 208-232, CIMNE, Barcelona, Spain

  
  

  Abstract

  A stabilized finite point method (FPM) for the meshless analysis of incompressible fluid flow problems 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 FPM is described. Examples of application of the stabilized FPM to the solution of incompressible flow problems are presented.

  Abstract
  A stabilized finite point method (FPM) for the meshless analysis of incompressible fluid flow problems is presented. The stabilization approach is based in the finite calculus [...]

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• The Particle Finite Element Method (PFEM). An effective numerical technique for solving marine, naval and harbour engineering problems

  E. Oñate, S. Idelsohn, M. Celigueta, B. Suarez

  (2013). Marine 2011, IV Int. Conference on Computational Methods in Marine Engineering. Selected papers, L. Eça, E. Oñate, J. García-Espinosa, T. Kvamsdal and P. Bergan (Eds.), pp. 65-81, Springer (preprint)

  
  

  Abstract

  We present some developments in the Particle Finite Element Method (PFEM) for the solution of complex coupled problems in marine, naval and harbour engineering involving fluid-soil-structure interaction (FSSI). The PFEM uses an updated Lagrangian description to model the motion of nodes (particles) in a continuum domain containing fluid, soil/rock and structures subdomains. A mesh connects the nodes defining the discretized domain where the governing equations for each of the constituent materials are solved with the FEM. The stabilization for dealing with an incompressibility material is introduced via the finite calculus (FIC) method. An incremental iterative scheme for solving the non linear transient FSSI problem is described. The procedure to model frictional contact conditions and material erosion at fluid-solid and solid-solid interfaces is described. We present examples of application of the PFEM to solve FSSI problems in marine, naval and harbour engineering such as the motion of rocks by water streams, the stability of breakwaters and constructions under sea waves, the sinking of ships and the collision of a ship with ice blocks.

  Abstract
  We present some developments in the Particle Finite Element Method (PFEM) for the solution of complex coupled problems in marine, naval and harbour engineering involving fluid-soil-structure [...]

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

  E. Oñate, S. Idelsohn, M. Celigueta, R. Rossi, J. Marti, J. Carbonell, P. Ryzhakov, B. Suárez

  (2011). Particle-Based Methods, Computational Methods in Applied Sciences, Springer, E. Oñate and R. Owen (Eds.), Vol. 25, pp. 1-48

  
  

  Abstract

  We present some developments in the formulation of the Particle Finite Element Method (PFEM) for analysis of complex coupled problems on fluid and solid mechanics in engineering accounting for fluid-structure interaction and coupled thermal effects, material degradation and surface wear. The PFEM uses an updated Lagrangian description to model the motion of nodes (particles) in both the fluid and the structure domains. Nodes are viewed as material points which can freely move and even separate from the main analysis domain representing, for instance, the effect of water drops. A mesh connects the nodes defining the discretized domain where the governing equations are solved, as in the standard FEM. The necessary stabilization for dealing with the incompressibility of the fluid is introduced via the finite calculus (FIC) method. An incremental iterative scheme for the solution of the non linear transient coupled fluid-structure problem is described. The procedure for modelling frictional contact conditions at fluid-solid and solid-solid interfaces via mesh generation are described. A simple algorithm to treat soil erosion in fluid beds is presented. An straight forward extension of the PFEM to model excavation processes and wear of rock cutting tools is described. Examples of application of the PFEM to solve a wide number of coupled problems in engineering such as the effect of large waves on breakwaters and bridges, the large motions of floating and submerged bodies, bed erosion in open channel flows, the wear of rock cutting tools during excavation and tunneling and the melting, dripping and burning of polymers in fire situations are presented.

  Abstract
  We present some developments in the formulation of the Particle Finite Element Method (PFEM) for analysis of complex coupled problems on fluid and solid mechanics in engineering [...]

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• The CIMNE model for generating knowledge on computational engineering and its transfer to society

  E. Oñate

  (2017). Research Report, Nº PI417

  
  

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• Langrangian formulation for incompressible fluids using finite calculus and the finite element method

  E. Oñate, S. Idelsohn, F. Pin

  (2003). Kuznetsov Y., Neittanmaki P. and Pironneau O. (Eds.),CIMNE, Barcelona, Spain

  
  

  Abstract

  We present a general formulation for incompressible fluid flow analysis using the finite element method (FEM) and a lagrangian description. The necessary stabilization for dealing with the incompressibility condition is introduced via the so called finite calculus (FIC) method. Both a quasi-implicit algorithm and a fractional step scheme are described. Examples of application of the lagrangian flow description are presented.

  Abstract
  We present a general formulation for incompressible fluid flow analysis using the finite element method (FEM) and a lagrangian description. The necessary stabilization for [...]

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• The CIMNE model for generating knowledge on computational engineering and its transfer to society

  E. Oñate

  (2017). Research Report, Nº PI417

  
  

  Abstract

  We present an overview of the model implemented by the International Centre for Numerical Methods in Engineering (CIMNE, www.cimne.com ) for  the generation of scientific and technical knowledge on computational engineering, understood in the broad sense, the subsequent generation of product resulting from the research activities and the transfer of these products to society for their exploitation in the industrial sector. We present examples of application of the CIMNE model to a number of academic, scientific and industry activities of CIMNE.

  Abstract
  We present an overview of the model implemented by the International Centre for Numerical Methods in Engineering (CIMNE, www.cimne.com ) for  the generation of scientific [...]

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• Estudio de estimación de parámetros constitutivos en el método de elementos discretos o de partículas

  C. Recarey, E. Oñate, J. Miquel, F. Zárate, J. Rojek, S. Burrell

  Monograph CIMNE (2005). M93

  
  

  Abstract

  Se presenta un modelo numérico que emplea elementos discretos esféricos o también denominados elementos distintos. Este modelo se aplica en la simulación de rocas, suelos, medios granulares y otros materiales. El movimiento de elementos esféricos se describe por medio de las ecuaciones de dinámica del cuerpo rígido. Se emplea en la formulación una integración explícita, la cual, brinda una buena eficiencia computacional.

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

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