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Article
Publication date: 3 October 2016

Zhou Lei, Esteban Rougier, Earl E. Knight, Luke Frash, James William Carey and Hari Viswanathan

In order to avoid the problem of volumetric locking often encountered when using constant strain tetrahedral finite elements, the purpose of this paper is to present a new…

215

Abstract

Purpose

In order to avoid the problem of volumetric locking often encountered when using constant strain tetrahedral finite elements, the purpose of this paper is to present a new composite tetrahedron element which is especially designed for the combined finite-discrete element method (FDEM).

Design/methodology/approach

A ten-noded composite tetrahedral (COMPTet) finite element, composed of eight four-noded low order tetrahedrons, has been implemented based on Munjiza’s multiplicative decomposition approach. This approach naturally decomposes deformation into translation, rotation, plastic stretches, elastic stretches, volumetric stretches, shear stretches, etc. The problem of volumetric locking is avoided via a selective integration approach that allows for different constitutive components to be evaluated at different integration points.

Findings

A number of validation cases considering different loading and boundary conditions and different materials for the proposed element are presented. A practical application of the use of the COMPTet finite element is presented by quantitative comparison of numerical model results against simple theoretical estimates and results from acrylic fracturing experiments. All of these examples clearly show the capability of the composite element in eliminating volumetric locking.

Originality/value

For this tetrahedral element, the combination of “composite” and “low order sub-element” properties are good choices for FDEM dynamic fracture propagation simulations: in order to eliminate the volumetric locking, only the information from the sub-elements of the composite element are needed which is especially convenient for cases where re-meshing is necessary, and the low order sub-elements will enable robust contact interaction algorithms, which maintains both relatively high computational efficiency and accuracy.

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Article
Publication date: 11 January 2022

Gang Liu, Fengshan Ma, Maosheng Zhang, Jie Guo and Jun Jia

Continua and discontinua coexist in natural rock materials. This paper aims to present an improved approach for addressing the mechanical response of rock masses based on the…

302

Abstract

Purpose

Continua and discontinua coexist in natural rock materials. This paper aims to present an improved approach for addressing the mechanical response of rock masses based on the combined finite-discrete element method (FDEM) proposed by Munjiza.

Design/methodology/approach

Several algorithms have been programmed in the new approach. The algorithms include (1) a simpler and more efficient algorithm to calculate the contact force; (2) An algorithm for tangential contact force closer to the actual physical process; (3) a plastic yielding criterion (e.g. Mohr-Coulomb) to modify the elastic stress for fitting the mechanical behavior of elastoplastic materials; and (4) a complete code for the mechanical calculation to be implemented in Matrix Laboratory (MATLAB).

Findings

Three case studies, including two standard laboratory experiments (uniaxial compression and Brazilian split test) and one engineering-scale anti-dip slop model, are presented to illustrate the feasibility of the Y-Mat code and its ability to deal with multi-scale rock mechanics problems. The results, including the progressive failure process, failure mode and trajectory of each case, are acceptable compared to other corresponding studies. It is shown that, the code is capable of modeling geotechnical and geological engineering problems.

Originality/value

This article gives an improved FDEM-based numerical calculation code. And, feasibility of the code is verified through three cases. It can effectively solve the geotechnical and geological engineering problems.

Details

Engineering Computations, vol. 39 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 February 1995

A. Munjiza, D.R.J. Owen and N. Bicanic

This paper discusses the issues involved in the development of combined finite/discrete element methods; both from a fundamental theoretical viewpoint and some related algorithmic…

3268

Abstract

This paper discusses the issues involved in the development of combined finite/discrete element methods; both from a fundamental theoretical viewpoint and some related algorithmic considerations essential for the efficient numerical solution of large scale industrial problems. The finite element representation of the solid region is combined with progressive fracturing, which leads to the formation of discrete elements, which may be composed of one or more deformable finite elements. The applicability of the approach is demonstrated by the solution of a range of examples relevant to various industrial sections.

Details

Engineering Computations, vol. 12 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 21 August 2009

Jiansheng Xiang, Antonio Munjiza, John‐Paul Latham and Romain Guises

As particulate systems evolve, sliding, rolling and collision contacts all produce forces that discrete element method (DEM) methods aim to predict. Verification of friction…

2568

Abstract

Purpose

As particulate systems evolve, sliding, rolling and collision contacts all produce forces that discrete element method (DEM) methods aim to predict. Verification of friction rarely takes high priority in validation studies even though friction plays a very important role in applications and in mathematical models for numerical simulation. The purpose of this paper is to address sliding friction in finite element method (FEM)/DEM and rolling friction in DEM.

Design/methodology/approach

Analytical solutions for “block sliding” were used to verify the authors' tangential contact force implementation of 2D FEM/DEM. Inspired by the kinetic art work Liquid Reflections by Liliane Lijn, which consists of free balls responding within a rotating shallow dish, DEM was used to simulate rolling, sliding and state‐of‐rest of spherical particles relative to horizontal and inclined, concave and flat spinning platforms. Various material properties, initial and boundary conditions are set which produce different trajectory regimes.

Findings

Simulation output is found to be in excellent agreement when compared with experimental results and analytical solutions.

Originality/value

The more widespread use of analytically solvable benchmark tests for DEM and FEM/DEM codes is recommended.

Details

Engineering Computations, vol. 26 no. 6
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 21 August 2009

Scott M. Johnson, John R. Williams and Benjamin K. Cook

Though the problem of resolving translational motion in particle methods is a relatively straightforward task, the complications of resolving rotational motion are non‐trivial…

558

Abstract

Purpose

Though the problem of resolving translational motion in particle methods is a relatively straightforward task, the complications of resolving rotational motion are non‐trivial. Many molecular dynamics and non‐deformable discrete element applications employ an explicit integration for resolving orientation, often involving products of matrices, which have well‐known drawbacks. The purpose of this paper is to investigate commonly used algorithms for resolving rotational motion and describe the application of quaternion‐based approaches to discrete element method simulations.

Design/methodology/approach

Existing algorithms are compared against a quaternion‐based reparameterization of both the central difference algorithm and the approach of Munjiza et al. for finite/discrete element modeling (FEM/DEM) applications for the case of torque‐free precession.

Findings

The resultant algorithms provide not only guaranteed orthonormality of the resulting rotation but also allow assumptions of small‐angle rotation to be relaxed and the use of a more accurate Taylor expansion instead.

Originality/value

The approaches described in this paper balance ease of implementation within existing explicit codes with computational efficiency and accuracy appropriate to the order of error in many discrete element method simulations.

Details

Engineering Computations, vol. 26 no. 6
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 March 2004

A. Munjiza and J.P. Latham

The combined finite‐discrete element method has been used to simulate the gravitational depositions of packs containing particles of cubical shape. This approach to the generation…

892

Abstract

The combined finite‐discrete element method has been used to simulate the gravitational depositions of packs containing particles of cubical shape. This approach to the generation of particle packs is based on the simulation of the dynamics of pack formation including interaction among individual particles, inertia and gravitational forces. The results of such an approach are compared to the experimental results to evaluate both feasibility and accuracy of the combined finite‐discrete element simulation of packing problems.

Details

Engineering Computations, vol. 21 no. 2/3/4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 March 2004

E. Rougier, A. Munjiza and J.P. Latham

It is now widely recognised that particle shape plays an important role in the behaviour of grand scale discontinua systems and may be partially responsible for some of the…

596

Abstract

It is now widely recognised that particle shape plays an important role in the behaviour of grand scale discontinua systems and may be partially responsible for some of the unexplained phenomena of particulate physics. It is therefore very important that a virtual discontinua modelling workbench includes a library comprising a large spectrum of shapes including real‐shaped particles of interest to scientists and engineers. In this context a question of selecting a particle from such a library arises. In this paper, a particular selection procedure based on shape selection chart is proposed.

Details

Engineering Computations, vol. 21 no. 2/3/4
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 4 July 2016

Wei Zhou, Wei Yuan, Gang Ma and Xiao-Lin Chang

The purpose of this paper is to propose a novel combined finite-discrete element method (FDEM), based on the cohesive zone model, for simulating rockslide problems at the…

950

Abstract

Purpose

The purpose of this paper is to propose a novel combined finite-discrete element method (FDEM), based on the cohesive zone model, for simulating rockslide problems at the laboratory scale.

Design/methodology/approach

The combined FDEM is realized using ABAQUS/Explicit. The rock mass is represented as a collection of elastic bulk elements glued by cohesive elements with zero thickness. To reproduce the tensile and shear micro-fractures in rock material, the Mohr-Coulomb model with tension cut-off is employed as the damage initiation criterion of cohesive elements. Three simulated laboratory tests are considered to verify the capability of combined FDEM in reproducing the mechanical behavior of rock masses. Three slope models with different joint inclinations are taken to illustrate the application of the combined FDEM to rockslide simulation.

Findings

The results show that the joint inclination is an important factor for inducing the progressive failure behavior. With a low joint inclination, the slope failure process is observed to be a collapse mode. As the joint inclination becomes higher, the failure mode changes to sliding and the steady time of rock blocks is shortened. Moreover, the runout distance and post-failure slope angle decrease as the joint inclination increases.

Originality/value

These studies indicate that the combined FDEM performed within ABAQUS can simulate slope stability problems for research purposes and is useful for studying the slope failure mechanism comprehensively.

Details

Engineering Computations, vol. 33 no. 5
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 2 May 2017

Guillermo Gonzalo Schiava D'Albano, Tomas Lukas, Fang Su, Theodosios Korakianitis and Ante Munjiza

Contact interaction and contact detection (CD) remain key components of any discontinua simulations. The methods of discontinua include combined finite-discrete element method…

370

Abstract

Purpose

Contact interaction and contact detection (CD) remain key components of any discontinua simulations. The methods of discontinua include combined finite-discrete element method (FDEM), discrete element method, molecular dynamics, etc. In recent years, a number of CD algorithms have been developed, such as Munjiza–Rougier (MR), Munjiza–Rougier–Schiava (MR-S), Munjiza-No Binary Search (NBS), Balanced Binary Tree Schiava (BBTS), 3D Discontinuous Deformation Analysis and many others. This work aims to conduct a numerical comparison of certain algorithms often used in FDEM for bodies of the same size. These include MR, MR-S, NBS and BBTS algorithms.

Design/methodology/approach

Computational simulations were used in this work.

Findings

In discrete element simulations where particles are introduced randomly or in which the relative position between particles is constantly changing, the MR and MR-S algorithms present an advantage in terms of CD times.

Originality/value

This paper presents a detailed comparison between CD algorithms. The comparisons are performed for problem cases with different lattices and distributions of particles in discrete element simulations. The comparison includes algorithms that have not been evaluated between them. Also, two new algorithms are presented in the paper, MR-S and BBTS.

Details

Engineering Computations, vol. 34 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 5 March 2018

Ivana Uzelac, Hrvoje Smoljanovic, Milko Batinic, Bernardin Peroš and Ante Munjiza

This paper aims to present a new numerical model for geometric nonlinear analysis of thin-shell structures based on a combined finite-discrete element method (FDEM).

203

Abstract

Purpose

This paper aims to present a new numerical model for geometric nonlinear analysis of thin-shell structures based on a combined finite-discrete element method (FDEM).

Design/methodology/approach

The model uses rotation-free, three-node triangular finite elements with exact formulation for large rotations, large displacements in conjunction with small strains.

Findings

The presented numerical results related to behaviour of arbitrary shaped thin shell structures under large rotations and large displacement are in a good agreement with reference solutions.

Originality/value

This paper presents new computationally efficient numerical model for geometric nonlinear analysis and prediction of the behaviour of thin-shell structures based on combined FDEM. The model is implemented into the open source FDEM package “Yfdem”, and is tested on simple benchmark problems.

Details

Engineering Computations, vol. 35 no. 1
Type: Research Article
ISSN: 0264-4401

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