• 제목/요약/키워드: discrete element modeling

검색결과 108건 처리시간 0.039초

Two scale modeling of behaviors of granular structure: size effects and displacement fluctuations of discrete particle assembly

  • Chu, Xihua;Yu, Cun;Xiu, Chenxi;Xu, Yuanjie
    • Structural Engineering and Mechanics
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    • 제55권2호
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    • pp.315-334
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    • 2015
  • This study's primary aim is to check the existence of a representative volume element for granular materials and determine the link between the properties (responses) of macro structures and the size of the discrete particle assembly used to represent a constitutive relation in a two-scale model. In our two-scale method the boundary value problem on the macro level was solved using finite element method, based on the Cosserat continuum; the macro stresses and modulus were obtained using a solution of discrete particle assemblies at certain element integration points. Meanwhile, discrete particle assemblies were solved using discrete element method under boundary conditions provided by the macro deformation. Our investigations focused largely on the size effects of the discrete particle assembly and the radius of the particle on macro properties, such as deformation stiffness, bearing capacity and the residual strength of the granular structure. According to the numerical results, we suggest fitting formulas linking the values of different macro properties (responses) and size of discrete particle assemblies. In addition, this study also concerns the configuration and displacement fluctuation of discrete particle assemblies on the micro level, accompanied with the evolution of bearing capacity and deformation on the macro level.

On the usefulness of discrete element computer modeling of particle packing for material characterization in concrete technology

  • Stroeven, P.;Hu, J.;Stroeven, M.
    • Computers and Concrete
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    • 제6권2호
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    • pp.133-153
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    • 2009
  • Discrete element modeling (DEM) in concrete technology is concerned with design and use of models that constitute a schematization of reality with operational potentials. This paper discusses the material science principles governing the design of DEM systems and evaluates the consequences for their operational potentials. It surveys the two families in physical discrete element modeling in concrete technology, only touching upon probabilistic DEM concepts as alternatives. Many common DEM systems are based on random sequential addition (RSA) procedures; their operational potentials are limited to low configuration-sensitivity features of material structure, underlying material performance characteristics of low structure-sensitivity. The second family of DEM systems employs concurrent algorithms, involving particle interaction mechanisms. Static and dynamic solutions are realized to solve particle overlap. This second family offers a far more realistic schematization of reality as to particle configuration. The operational potentials of this family involve valid approaches to structure-sensitive mechanical or durability properties. Illustrative 2D examples of fresh cement particle packing and pore formation during maturation are elaborated to demonstrate this. Mainstream fields of present day and expected application of DEM are sketched. Violation of the scientific knowledge of to day underlying these operational potentials will give rise to unreliable solutions.

콘크리트의 변형률 국소화 및 진행성 파괴에 관한 연구 (Study on Strain Localization and Progressive Failure of Concrete)

  • 송하원;김형운;우승민
    • 콘크리트학회논문집
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    • 제11권3호
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    • pp.181-192
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    • 1999
  • The progressive failure following strain localization in concrete can be analyzed effectively using finite element modeling of fracture process zone of concrete with a finite element embedded discontinuity. In this study, a finite element with embedded discontinuous line is utilized for the analysis of progressive failure in concrete. The finite element with embedded discontinuity is a kind of discrete crack element, but the difficulties in discrete crack approach such as remeshing or adding new nodes along with crack growth can be avoided. Using a discontinuous shape function for this element, the displacement discontinuity is embedded within an element and its constitutive equation is modeled from the modeling of fracture process zone. The element stiffness matrix is derived and its dual mapping technique for numerical integration is employed. Then, a finite element analysis program with employed algorithms is developed and failure analysis results using developed finite element program are verified through the comparison with experimental data and other analysis results.

2차원 개별요소법을 이용한 도상자갈 생성 알고리즘 개발 (Development of 2-D DEM (Discrete Element Method) algorithm to model ballast and sleeper)

  • 김대상;황선근
    • 한국철도학회논문집
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    • 제6권3호
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    • pp.174-178
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    • 2003
  • This paper presents the development of 2-dimensional discrete element algorithm to generate circle and line elements for the simulation of the ballast and sleeper in railway. An example of randomly distributed circle elements show a good applicability of this algorithm for the modeling of the behaviors of ballast. The output about unbalaned force, particle velocity, and total energy conservation from the code is evaluated to check if the calculation is conducted properly.

Numerical investigation of the effect of impact on the rockfall protective embankment reinforced with geogrid

  • Mohammad Reza Abroshan;Majid Noorian-Bidgoli
    • Geomechanics and Engineering
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    • 제33권4호
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    • pp.353-367
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    • 2023
  • The construction of a protective embankment is a suitable strategy to stop and control high-energy rock blocks' impacts during the rockfall phenomenon. In this paper, based on the discrete element numerical method, by modeling an existing embankment reinforced with geogrid, its stability status under the impact of a rock block with two types of low and high kinetic energy, namely 2402 and 4180 kJ, respectively, has been investigated. The modeling results show that the use of geogrid has caused the displacement in the front and back of the embankment to decrease by more than 30%. In this case, the reinforced embankment has stopped the rock block earlier. The displacements obtained from the DEM modeling are compared with the displacements measured from an actual practical experiment to evaluate the results' validity. Comparison between the results shows that the displacement values are close together, while the maximum percentage error in previous studies by an analytical method and the finite element method was 76.4% and 36.6%, respectively. Therefore, the obtained results indicate the discrete numerical method's high ability compared to other numerical and analytical methods to simulate and design the geogrid-reinforced soil embankment under natural disasters such as rockfall with a minor error.

Discrete element modeling of masonry structures: Validation and application

  • Pulatsu, Bora;Bretas, Eduardo M.;Lourenco, Paulo B.
    • Earthquakes and Structures
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    • 제11권4호
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    • pp.563-582
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    • 2016
  • The failure mechanism and maximum collapse load of masonry structures may change significantly under static and dynamic excitations depending on their internal arrangement and material properties. Hence, it is important to understand correctly the nonlinear behavior of masonry structures in order to adequately assess their safety and propose efficient strengthening measures, especially for historical constructions. The discrete element method (DEM) can play an important role in these studies. This paper discusses possible collapse mechanisms and provides a set of parametric analyses by considering the influence of material properties and cross section morphologies on the out of plane strength of masonry walls. Detailed modeling of masonry structures may affect their mechanical strength and displacement capacity. In particular, the structural behavior of stacked and rubble masonry walls, portal frames, simple combinations of masonry piers and arches, and a real structure is discussed using DEM. It is further demonstrated that this structural analysis tool allows obtaining excellent results in the description of the nonlinear behavior of masonry structures.

DEM을 이용한 회전원통에서의 세탁물의 동역학적 해석 (Dynamic Analysis of Fabric in a Rotating Horizontal Drum Using the Discrete Element Method)

  • Park, Jun-Young;Wassgren, Carl R.
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.1839-1844
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    • 2003
  • In order to provide a tool for designing more efficient methods of mixing fabric, a simplified discrete element computational model was developed for modeling fabric dynamics in a rotating horizontal drum. Because modeling the interactions between actual pieces of fabric is quite complex, a simplified model was developed where individual pieces of bundled fabric are represented by spherical particles. The simulations are used to investigate fabric bundle kinematics, the power required to drive the rotating drum, and the power dissipated through normal and tangential contacts. Parametric studies indicate only fill percentage, drum rotation speed, and friction coefficient play significant roles in the fabric bundle dynamics.

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Modeling concrete fracturing using a hybrid finite-discrete element method

  • Elmo, Davide;Mitelman, Amichai
    • Computers and Concrete
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    • 제27권4호
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    • pp.297-304
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    • 2021
  • The hybrid Finite-Discrete Element (FDEM) approach combines aspects of both finite elements and discrete elements with fracture mechanics principles, and therefore it is well suited for realistic simulation of quasi-brittle materials. Notwithstanding, in the literature its application for the analysis of concrete is rather limited. In this paper, the proprietary FDEM code ELFEN is used to model concrete specimens under uniaxial compression and indirect tension (Brazilian tests) of different sizes. The results show that phenomena such as size effect and influence of strain-rate are captured using this modeling technique. In addition, a preliminary model of a slab subjected to dynamic shear punching due to progressive collapse is presented. The resulting fracturing pattern of the impacted slab is similar to observations from actual collapse.

이산요소법을 활용한 점성토 환경에서의 토양 입자 크기에 따른 몰드보드 플라우 견인력 예측 시뮬레이션 (Simulation study on draft force prediction of moldboard plow according to cohesive soil particle size using the discrete element method)

  • 김민승;배보민;정대위;안장현;최세오;;성시원;김연수;김용주
    • 드라이브 ㆍ 컨트롤
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    • 제21권3호
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    • pp.46-55
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    • 2024
  • In the agricultural machinery field, load analysis is mostly done through field tests. However, field tests are time-consuming and costly. There are also limitations in test conditions due to weather conditions. To overcome these environmental limitations, research on load analysis through simulation in a virtual environment is actively being conducted. This study aimed to select the most appropriate soil particle size for modeling by analyzing the effect of soil particle size on the prediction of draft force of the implement using simulation and soil particle modeling in a virtual environment with the discrete element method (DEM) software. The accuracy was verified by simulating the draft force for the same moving speed by soil particle size. For soil particle modeling, DEM soil modeling was performed by designing soil property measurement procedure. Soil particle correction was performed with a virtual vane shear test. Average DEM simulation results showed an error of 27.39% (19.43~40.66%) compared to actual measured data. The possibility of improvement was confirmed through additional research. Results of this study provide useful information for selecting soil particle size in soil modeling using DEM from the perspective of agricultural machinery research.

Damage prediction in the vicinity of an impact on a concrete structure: a combined FEM/DEM approach

  • Rousseau, Jessica;Frangin, Emmanuel;Marin, Philippe;Daudeville, Laurent
    • Computers and Concrete
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    • 제5권4호
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    • pp.343-358
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    • 2008
  • This article focuses on concrete structures submitted to impact loading and is aimed at predicting local damage in the vicinity of an impact zone as well as the global response of the structure. The Discrete Element Method (DEM) seems particularly well suited in this context for modeling fractures. An identification process of DEM material parameters from macroscopic data (Young's modulus, compressive and tensile strength, fracture energy, etc.) will first be presented for the purpose of enhancing reproducibility and reliability of the simulation results with DE samples of various sizes. The modeling of a large structure by means of DEM may lead to prohibitive computation times. A refined discretization becomes required in the vicinity of the impact, while the structure may be modeled using a coarse FE mesh further from the impact area, where the material behaves elastically. A coupled discrete-finite element approach is thus proposed: the impact zone is modeled by means of DE and elastic FE are used on the rest of the structure. The proposed approach is then applied to a rock impact on a concrete slab in order to validate the coupled method and compare computation times.