• Title/Summary/Keyword: discrete element modeling

Search Result 108, Processing Time 0.02 seconds

RC beams retrofitted using external bars with additional anchorages-a finite element study

  • Vasudevan, G.;Kothandaraman, S.
    • Computers and Concrete
    • /
    • v.16 no.3
    • /
    • pp.415-428
    • /
    • 2015
  • Study on flexural retrofitting of RC beams using external bars with additional intermediate anchorages at soffit is reported in this paper. Effects of varying number of anchorages in the external bars at soffit were studied by finite element analysis using ANSYS 12.0 software. The results were also compared with available experimental results for beam with only two end anchorages. Two sets of reference and retrofitted beam specimens with two, three, four and five anchorages were analysed and the results are reported. FE modeling and non-linear analysis was carried out by discrete reinforcement modeling using Solid65, Solid45 and Link8 elements. Combin39 spring elements were used for modeling the frictional contact between the soffit and the external bars. The beam specimens were subjected to four-point bending and incremental loading was applied till failure. The entire process of modeling, application of incremental loading and generation of output in text and graphical format were carried out using ANSYS Parametric Design Language.

An efficient finite element modeling of dynamic crack propagation using a moving node element

  • Kwon, Y.W.;Christy, C.
    • Structural Engineering and Mechanics
    • /
    • v.2 no.2
    • /
    • pp.173-184
    • /
    • 1994
  • The objective of this study was to develop a simple and efficient numerical modeling technique for dynamic crack propagation using the finite element method. The study focused on the analysis of a rapidly propagation crack in an elastic body. As already known, discrete crack tip advance with the stationary node procedure results in spurious oscillation in the calculated energy terms. To reduce the spurious oscillation, a simple and efficient moving node procedure is proposed. The procedure does require neither remeshing the discretization nor distorting the original mesh. Two different central difference schemes are also evaluated and compared for dynamic crack propagation problem.

Numerical Modeling of Soil-Cement based on Discrete Element Method (개별요소법을 이용한 시멘트 혼합토의 수치모델링)

  • Jeong, Sang-Guk
    • Journal of the Korean Geosynthetics Society
    • /
    • v.15 no.4
    • /
    • pp.33-42
    • /
    • 2016
  • Discrete Element Method was conducted for rock and coarse-grained materials in development of granular mechanics and related numerical model due to analyze and apply micromechanical property. And it was verified that the analysis to consider bonding effect was insufficient. In this study, to overcome limits of existing method, it was conducted to analyze difference between indoor test result and bonding effect using $PFC^{3D)}$. For indoor test of mixed soil, uniaxial compression tests by curing time and by cement content were performed. And, DEM to suitable for each condition of indoor test was conducted. In the result of this study, in terms of geotechnics, it was verified that DEM can be used for application as numerical laboratory as well as prediction of micro and macro behavior about bonding effect of mixed soil.

Prediction of Draft Force of Moldboard Plow according to Travel Speed in Cohesive Soil using Discrete Element Method (이산요소법을 활용한 점성토 환경에서의 작업 속도에 따른 몰드보드 플라우 견인력 예측)

  • Bo Min Bae;Dae Wi Jung;Dong Hyung Ryu;Jang Hyeon An;Se O Choi;Yeon Soo Kim;Yong Joo Kim
    • Journal of Drive and Control
    • /
    • v.20 no.4
    • /
    • pp.71-79
    • /
    • 2023
  • In the field of agricultural machinery, various on-field tests are conducted to measure design load for optimal design of agricultural equipment. However, field test procedures are costly and time-consuming, and there are many constraints on field soil conditions due to weather, so research on utilizing simulation to overcome these shortcomings is needed. Therefore, this study aimed to model agricultural soils using discrete element method (DEM) software. To simulate draft force, predictions are made according to travel speed and compared to field test results to validate the prediction accuracy. The measured soil properties are used for DEM modeling. In this study, the soil property measurement procedure was designed to measure the physical and mechanical properties. DEM soil model calibration was performed using a virtual vane shear test instead of the repose angle test. The DEM simulation results showed that the prediction accuracy of the draft force was within 4.8% (2.16~6.71%) when compared to the draft force measured by the field test. In addition, it was confirmed that the result was up to 72.51% more accurate than those obtained through theoretical methods for predicting draft force. This study provides useful information for the DEM soil modeling process that considers the working speed from the perspective of agricultural machinery research and it is expected to be utilized in agricultural machinery design research.

A Study on Modeling for the Magnetic Bearing System by Numerical Analysis (수치 해석을 통한 자기 베어링 시스템의 모델링에 관한 연구)

  • Shim, S.H.;Choi, M.S.;Kim, C.H.;Moon, D.H.;Yang, J.H.
    • Journal of Power System Engineering
    • /
    • v.5 no.4
    • /
    • pp.53-60
    • /
    • 2001
  • This paper considers a modeling for the MIMO magnetic bearing system. The rotor is flexible and has a complex shape. To obtain the nominal plant transfer functions, we perform a numerical analysis by using the finite element method(F.E.M.) for the rotor's dynamics, and make a nominal model by reducing the modes from the results. And, we have experimented on the frequency response by a closed-loop identification method, and compared it with the simulation's result on the closed-loop control system.

  • PDF

Active Vibration Control of Composite Shell Structure using Modal Sensor/Actuator System

  • Kim, Seung-Jo;Hwang, Joon-Seok;Mok, Ji-Won
    • International Journal of Aeronautical and Space Sciences
    • /
    • v.7 no.1
    • /
    • pp.106-117
    • /
    • 2006
  • The active vibration control of composite shell structure has been performed with the optimized sensor/actuator system. For the design of sensor/actuator system, a method based on finite element technique is developed. The nine-node Mindlin shell element has been used for modeling the integrated system of laminated composite shell with PVDF sensor/actuator. The distributed selective modal sensor/actuator system is established to prevent the effect of spillover. Electrode patterns and lamination angles of sensor/actuator are optimized using genetic algorithm. Continuous electrode patterns are discretized according to finite element mesh, and orientation angle is encoded into discrete values using binary string. Sensor is designed to minimize the observation spillover, and actuator is designed to minimize the system energy of the control modes under a given initial condition. Modal sensor/actuator for the first and the second mode vibration control of singly curved cantilevered composite shell structure are designed with the method developed on the finite element method and optimization. For verification, the experimental test of the active vibration control is performed for the composite shell structure. Discrete LQG method is used as a control law.

Evaluation of Dynamic Behavior Characteristics of Cheomseongdae Considering Earthquake Load (지진 하중을 고려한 첨성대의 동적 거동 특성 평가)

  • Kim, Ho-Soo;Lee, Ha-Na
    • Journal of Korean Association for Spatial Structures
    • /
    • v.19 no.4
    • /
    • pp.35-44
    • /
    • 2019
  • Recently, the occurrence frequency of earthquake has increased in Korea, and many cultural assets have been damaged. Cheomseongdae is a valuable cultural assets that must be preserved historically and culturally. But, the masonry structure such as Chemseongdae is vulnerable to lateral forces. Therefore, in this study, structural modeling and dynamic analysis are performed to reflect the ground state and structural form of Cheomseongdae. Also, discrete element analysis technique is applied and dynamic behavior characteristics are analyzed according to earthquake load. For this purpose, displacements and stresses according to locations are reviewed and then swelling and distortion are analyzed.

Response of a rocksalt crystal to electromagnetic wave modeled by a multiscale field theory

  • Lei, Yajie;Lee, James D.;Zeng, Xiaowei
    • Interaction and multiscale mechanics
    • /
    • v.1 no.4
    • /
    • pp.467-476
    • /
    • 2008
  • In this work, a nano-size rocksalt crystal (magnesium oxide) is considered as a continuous collection of unit cells, while each unit cell consists of discrete atoms; and modeled by a multiscale concurrent atomic/continuum field theory. The response of the crystal to an electromagnetic (EM) wave is studied. Finite element analysis is performed by solving the governing equations of the multiscale theory. Due to the applied EM field, the inhomogeneous motions of discrete atoms in the polarizable crystal give rise to the change of microstructure and the polarization wave. The relation between the natural frequency of this system and the driving frequency of the applied EM field is found and discussed.

Trends in Materials Modeling and Computation for Metal Additive Manufacturing

  • Seoyeon Jeon;Hyunjoo Choi
    • Journal of Powder Materials
    • /
    • v.31 no.3
    • /
    • pp.213-219
    • /
    • 2024
  • Additive Manufacturing (AM) is a process that fabricates products by manufacturing materials according to a three-dimensional model. It has recently gained attention due to its environmental advantages, including reduced energy consumption and high material utilization rates. However, controlling defects such as melting issues and residual stress, which can occur during metal additive manufacturing, poses a challenge. The trial-and-error verification of these defects is both time-consuming and costly. Consequently, efforts have been made to develop phenomenological models that understand the influence of process variables on defects, and mechanical/ electrical/thermal properties of geometrically complex products. This paper introduces modeling techniques that can simulate the powder additive manufacturing process. The focus is on representative metal additive manufacturing processes such as Powder Bed Fusion (PBF), Direct Energy Deposition (DED), and Binder Jetting (BJ) method. To calculate thermal-stress history and the resulting deformations, modeling techniques based on Finite Element Method (FEM) are generally utilized. For simulating the movements and packing behavior of powders during powder classification, modeling techniques based on Discrete Element Method (DEM) are employed. Additionally, to simulate sintering and microstructural changes, techniques such as Monte Carlo (MC), Molecular Dynamics (MD), and Phase Field Modeling (PFM) are predominantly used.

3D thermo-hydro-mechanical coupled discrete beam lattice model of saturated poro-plastic medium

  • Hadzalic, Emina;Ibrahimbegovic, Adnan;Dolarevic, Samir
    • Coupled systems mechanics
    • /
    • v.9 no.2
    • /
    • pp.125-145
    • /
    • 2020
  • In this paper, we present a 3D thermo-hydro-mechanical coupled discrete beam lattice model of structure built of the nonisothermal saturated poro-plastic medium subjected to mechanical loads and nonstationary heat transfer conditions. The proposed model is based on Voronoi cell representation of the domain with cohesive links represented as inelastic Timoshenko beam finite elements enhanced with additional kinematics in terms of embedded strong discontinuities in axial and both transverse directions. The enhanced Timoshenko beam finite element is capable of modeling crack formation in mode I, mode II and mode III. Mode I relates to crack opening, mode II relates to in-plane crack sliding, and mode III relates to the out-of-plane shear sliding. The pore fluid flow and heat flow in the proposed model are governed by Darcy's law and Fourier's law for heat conduction, respectively. The pore pressure field and temperature field are approximated with linear tetrahedral finite elements. By exploiting nodal point quadrature rule for numerical integration on tetrahedral finite elements and duality property between Voronoi diagram and Delaunay tetrahedralization, the numerical implementation of the coupling results with additional pore pressure and temperature degrees of freedom placed at each node of a Timoshenko beam finite element. The results of several numerical simulations are presented and discussed.