JOURNALS

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• BIMtable: your digital office at the building site

  J. Mora, G. Peffer, E. Oñate

  Presentations Repository of the International Centre for Numerical Methods in Engineering (CIMNE) (2017).

  
  

  Abstract

  The digitization process applied to the construction sector seems to be articulated through the "Building Information Modeling" (BIM), which, as is well known, includes not only the three-dimensional (3D) representation of the works, but its many other dimensions, such as temporal information, budget, sustainability, services, etc. The BIM, as a technology, process and ecosystem, is effectively offering solutions for the entire life cycle of a project, in its design, execution and operation phases, and for all the agents linked to it, that is, for all the professionals of the construction sector without exception. The BIMtable concept is born from considering that it is precisely the construction, the most complex environment - changing and severe - the most interesting scenario to incorporate the novelties offered by the BIM, as well as all the technologies that complement it, to achieve the digitalization of the construction in its broadest sense. It is at the work site where real-time monitoring of its progress can be made, using sensors, IoT, cameras or the information provided by the workers themselves. It is in the construction where the different professionals need to access the information of the project, as it has been developed and modeled, to follow and execute the instructions of the architect.

  Abstract
  The digitization process applied to the construction sector seems to be articulated through the "Building Information Modeling" (BIM), which, as is well known, includes [...]

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• A coupled FEM-DEM procedure for predicting blasting operations in tunnels

  F. Zarate, J. Gonzalez, J. Miquel, R. Lohner, E. Oñate

  Underground Space (2018). Vol. 3 (3), pp. 310-316

  
  

  Abstract

  We present recent developments in the coupling of the finite element method (FEM) and the discrete element method (DEM) for analysis of rock blasting operations in tunnels. The coupled FEM-DEM technique has proven to be an efficient technique for predicting the multi-fracture of rock induced by the loads generated in blasting situations. The coupled FEM-DEM procedure is applied in the tunnel construction, as well as to gas pressure blasting pyrotechnics situations to break rock for excavation of the tunnel front. In the latter case the effect of gas explosion is modelled by solving with the FEM the equations of gas dynamics in the analysis domain. The effect of the gas forces in the underlying rock mass is modelled with an embedded fluid-structure interaction method. This allows us to accurately predicting the progressive multi-fracture of the rock accounting for the penetration of the gas in the fractured domain modelled with the FEM-DEM procedure. The efficiency of the coupled FEM-DEM technique is demonstrated in several examples of fracture tests and rock blasting problems related to tunnel engineering'''.''' The examples presented show that the combination of the DEM with simple 3-noded linear triangular elements correctly captures the onset of fractures and their evolution [1].

  Abstract
  We present recent developments in the coupling of the finite element method (FEM) and the discrete element method (DEM) for analysis of rock blasting operations in tunnels. [...]

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

  E. Oñate, F. Zarate, M. Celigueta, J. Gonzalez, J. Miquel, J. Carbonell, F. Garcia, S. Latorre, M. Santasusana

  (2017). Research Report, Nº PI416

  
  

  Abstract

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

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• A machine learning based methodology for anomaly detection in dam behaviour

  F. Salazar, E. Oñate, M. Toledo

  Monograph CIMNE (2017). M170

  
  

  Abstract

  Dam behaviour is difficult to predict with high accuracy. Numerical models for structural calculation solve the equations of continuum mechanics, but are subject to considerable uncertainty as to the characterisation of materials, especially with regard to the foundation. As a result, these models are often incapable to calculate dam behaviour with sufficient precision. Thus, it is difficult to determine whether a given deviation between model results and monitoring data represent a relevant anomaly or incipient failure. By contrast, there is a tendency towards automatising dam monitoring devices, which allows for increasing the reading frequency and results in a greater amount and variety of data available, such as displacements, leakage, or interstitial pressure, among others. This increasing volume of dam monitoring data makes it interesting to study the ability of advanced tools to extract useful information from observed variables. In particular, in the field of Machine Learning (ML), powerful algorithms have been developed to face problems where the amount of data is much larger or the underlying phenomena is much less understood. In this monograph, the possibilities of machine learning techniques are analysed for application to dam structural analysis based on monitoring data. The typical characteristics of the data sets available in dam safety are taking into account, as regards their nature, quality and size. A critical literature review is performed, from which the key issues to consider for implementation of these algorithms in dam safety are identified. A comparative study of the accuracy of a set of algorithms for predicting dam behaviour is carried out, considering radial and tangential displacements and leakage flow in a 100-m high dam. The results suggest that the algorithm called “Boosted Regression Trees” (BRT) is the most suitable, being more accurate in general, while flexible and relatively easy to implement. The possibilities of interpretation of the mentioned algorithm are evaluated, to identify the shape and intensity of the association between external variables and the dam response, as well as the effect of time. The tools are applied to the same test case, and allow more accurate identification of the time effect than the traditional statistical method. Finally, a methodology for the implementation of predictive models based on BRT for early detection of anomalies is presented, together with its implementation in an interactive tool that provides information on dam behaviour, through a set of selected devices. It allows the user to easily verify whether the actual data for each of these devices are within a pre-defined normal operation interval.

  Abstract
  Dam behaviour is difficult to predict with high accuracy. Numerical models for structural calculation solve the equations of continuum mechanics, but are subject to considerable [...]

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• Numerical Techniques for non-linear analysis of structures combining Discrete Element and Finite Element Methods

  M. Santasusana, E. Oñate

  Monograph CIMNE (2016). M168

  
  

  Abstract

  This works encompasses a broad review of the basic aspects of the Discrete Element Method for its application to general granular material handling problems with special emphasis on the topics of particle-structure interaction and the modelling of cohesive materials. On the one hand, a special contact detection algorithm has been developed for the case of spherical particles representing the granular media in contact with the finite elements that discretize the surface of rigid structures. The method, named Double Hierarchy Method, improves the existing state of the art in the field by solving the problems that non-smooth contact regions and multi contact situations present. This topic is later extended to the contact with deformable structures by means of a coupled DE-FE method. To do so, a special procedure is described aiming to consistently transfer the contact forces, which are first calculated on the particles, to the nodes of the FE representing the solids or structures. On the other hand, a model developed by Oñate et al. for the modelling of cohesive materials with the DEM is numerically analysed to draw some conclusions about its capabilities and limitations.  In parallel to the theoretical developments, one of the objectives of the thesis is to provide the industrial partner of the doctoral programme, CITECHSA, a computer software called DEMPack (www.cimne.com/dem/) that can apply the coupled DE-FE procedure to real engineering projects. One of the remarkable applications of the developments in the framework of the thesis has been a project with the company Weatherford Ltd. involving the simulation of concrete-like material testing.

  Abstract
  This works encompasses a broad review of the basic aspects of the Discrete Element Method for its application to general granular material handling problems with special emphasis [...]

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• Evaluating manoeuvering and seakeeping performance of a surface effect ship

  E. Oñate

  (2012). Technical Report, IT629

  
  

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• Some algorithms to correct a geometry in order to create a finite element mesh

  R. Ribó, G. Bugeda, E. Oñate

  Computers and Structures (2002). Vol. 80 (16-17), pp. 1399-1408

  
  

  Abstract

  One of the major difficulties in meshing 3D complex geometries is to deal with non proper geometrical definitions coming from CAD systems. Typically, CAD systems do not take care of the proper definition of the geometries for the analysis purposes. In addition, the use of standard CAD files (IGES, VDA,...) for the transfer of geometries between different systems introduce some additional difficulties. In this work, a collection of algorithms to repair and/or to improve the geometry definitions are provided. The aim of these algorithms is to make as easy as possible the generation of a mesh over complex geometries given some minimum requirements of quality and correctness. The geometrical model will be considered as composed of a set of NURBS lines and trimmed surfaces. Some examples of application of the algorithms and of the meshes generated from the corrected geometry are also presented in this work

  Abstract
  One of the major difficulties in meshing 3D complex geometries is to deal with non proper geometrical definitions coming from CAD systems. Typically, CAD systems do not take [...]

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• A computational model for the evaluation of the spray generation of a Wave Adaptive Modular Vessel

  J. García-Espinosa, E. Oñate, B. Servan Camas, P. Nadukandi, P. Becker

  Collection of Papers on Computational Methods in Naval Architecture and Offshore Engineering (2020).

  
  

  Abstract

  This paper presents part of the work done within the project 'Advanced Numerical Simulation and Performance Evaluation of WAM-V® in Spray Generating Conditions' developed by the International Center for Numerical Methods in Engineering (CIMNE) under Navy Grant N62909-12-1-7101 issued by the Office of Naval Research Global. One of the primary goals of that project was the development of a computational model for simulation of the Wave Adaptive Modular Vessel (WAM-V®) under spray generating conditions. For this purpose, a Semi-Lagrangian Particle Finite Element Method (SL-PFEM) has been applied. This is the latest development within the framework of the so-called Particle Finite Element Method (PFEM), using the X-IVAS (eXplicit Integration along the Velocity and Acceleration Streamlines) scheme. In this paper we demonstrate the applicability of the SL-PFEM using the X-IVAS scheme for the simulation of the Wave Adaptive Modular Vehicle under spray generating conditions.

  Abstract
  This paper presents part of the work done within the project 'Advanced Numerical Simulation and Performance Evaluation of WAM-V® in Spray Generating Conditions' [...]

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• Robust volume mesh generation for non-watertight geometries

  A. Coll, P. Dadvand, E. Oñate

  Monograph CIMNE (2014). M146

  
  

  Abstract

  Nowadays large part of the time needed to perform a numerical simulation is spent in preprocessing, especially in the geometry cleaning operations and mesh generation. Furthermore, these operations are not easy to automatize because they depend strongly on each geometrical model and they often need human interaction. Many of these operations are needed to obtain a watertight geometry. Even with a clean geometry, classical unstructured meshing methods (like Delaunay or Advancing Front based ones) present critical weak points like the need of a given quality in the boundary mesh or a relatively smooth size transition. These aspects decrease their robustness and imply an extra e ort in order to reach the nal mesh. Octree based meshers try to relax some of these requirements. In the present work an octree based mesher for unstructured tetrahedra is presented. The proposed mesher ensures the mesh generation avoiding most of the geometry cleaning operations. It is based in the following steps: t an octree onto the model, re ne it following given criteria, apply a tetrahedra pattern to the octree cells and adapt the tetrahedra close to the contours in order to represent accurately the boundary shape. An important and innovative aspect of the proposed algorithm is it ensures the nal mesh preserves the topology and the geometric features of the original model. The method uses a Ray Casting based algorithm for the identi cation of the inner and outer parts of the volumes involved in the model. This technique allows the mesh generation of volumes even with non-watertight boundaries, and also opens the use of the mesher for immersed methods only applying slight modi cations to the algorithm. The main advantages of the presented mesher are: robustness, no need for watertight boundaries, independent on the contour mesh quality, preservation of geometrical features (corners and ridges), original geometric topology guaranteed, accurate representation of the contours, valid for immersed methods, and fast performance. A lot of time in the preprocessing part of the numerical simulation is saved thanks to the robustness of the mesher, which allows skipping most of the geometry cleaning operations. A shared memory parallel implementation of the algorithm has been done. The e ectiveness of the algorithm and its implementation has been veri ed by some validation examples.

  Abstract
  Nowadays large part of the time needed to perform a numerical simulation is spent in preprocessing, especially in the geometry cleaning operations and mesh generation. Furthermore, [...]

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• The Cycle of Ideas in research, development and technology transfer

  E. Oñate

  (2011). Research Report, Nº PI358

  
  

  Abstract

  When people talks about research, development and technology transfer (RTD in short) and commercial industrial activities, it is quite usual to mix up objectives, resources and responsibilities. There is a growing opinion, spread by some public administrators and the media, that research groups at universities and RTD centers must be "profitable". In few words, many persons would wish that research is funded with competitive funds or even loans (either public or private) and that the outcomes of the research get into the market rapidly, so that the profits from marketing the corresponding products will allow research groups to be financially self-sustaining.

  Abstract
  When people talks about research, development and technology transfer (RTD in short) and commercial industrial activities, it is quite usual to mix up objectives, resources [...]

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