Papers by Keyword: Discrete Model

Paper TitlePage

Authors: Qing Zhi Wen, Yang Li, Xi Xu, Meng Li, Hai Peng Li
Abstract: The permeability of the shale reservoir is nanoDarcy. After fracturing the fractures that appear in the shale reservoir are very complex, which can’t be described by conventional method. The conventional flow instrument for the fractures is improved. A more applicable flow chamber is remade to evaluate the flow conductivity of the network-like fractures more accurately. The model of the network-like fractures includes the marble and high-intensity proppants.
1055
Authors: Zhao Zhong Zhou, Kai Ping Feng, Ju Long Yuan
Abstract: A new polishing method by using fixed soft abrasive film is proposed to polish the end-face of the optic fiber connector. In order to study the wear property of the fixed soft abrasive film, the Particle Flow Code program was employed to simulate the interaction of surface topography. The discrete element model of the optic fiber connector and the fixed soft abrasive film were established. Through the interaction of the surface of two models, the process of contact and friction between the fixed soft abrasive film and the end-face of the optic fiber connector could be simulated. Simulation results showed that the main factors affecting the wear of the fixed soft abrasive film were pressure and speed, which mainly affected the normal stress and the tangential stress respectively. And the wear of the surface was mainly related to pressure and speed. The greater the speed and pressure were, the more serious wear of the fixed soft abrasive film was.
452
Authors: Jan Eliáš
Abstract: The adaptive discretization technique for static discrete models of random geometry based on Voronoi cells is developed here. It is based on adding randomly located nodes into the highly stressed regions and updating the discretization based on those nodes before the crack may initiate in or propagate through the regions.
579
Authors: Roman Wendner, Kresimir Nincevic, Ioannis Boumakis, Lin Wan
Abstract: For decades, concrete plays an important role worldwide as a structural material. Construction planning and reliability assessment require a thorough insight of the effects that determine concrete lifetime evolution. This study shows the experimental characterization as well as the results of subsequent aging simulations utilizing and coupling a Hygro-thermo-chemical (HTC) model and the Lattice Discrete Particle Model (LDPM) with aging effects for concretes at various early ages. The HTC component of the computational framework allows taking into account any form of environmental curing conditions as well as known material constituents and predicts the level of concrete maturity. Mechanical response and damage are captured by the well-established LDPM, which is formulated in the framework of discrete meso-scale constitutive models. The chemo-mechanical coupling is accomplished by a set of aging functions that link the meso-scale material properties to an effective aging degree, accounting for cement hydration, silica fume reaction, polymerization, and temperature effects. After introducing the formulations the framework is applied to experimental data of 3 standard low and higher strength concretes. Investigated tests include two types of unconfined compression, Brazilian splitting, three-point-bending, and wedge splitting. Following the model calibration the framework is validated by purely predictive simulations of structural level experimental data obtained at different ages for the same concretes.
1090
Authors: Tae Hyun Kim, Han Lim Song, Sung Ho Hwang, Hyun Soo Kim
Abstract: This paper presents a discrete analysis approach to investigate performance of the DMF. An arcspring installed between the flywheels is modeled as n - discrete elements. Each element consists of mass, spring and nonlinear friction element. The nonlinear friction model is proposed to describe Stribeck effect and viscous friction depending on the relative sliding velocity. The DMF performance such as hysterisis characteristics are investigated by comparing the experimental result. In addition, the torque characteristics transmitted to the driveshaft are evaluated by comparing the test result from manual transmission bench tester. It is found that discrete DMF model described the automotive driveline behavior closely. It is also found that the friction characteristics of the arcspring depends on the relative sliding velocity between the friction surfaces, which varies depending on the relative position of the DMF arcspring.
1607
Authors: Gulbahar Tohti, Mamtimin Gheni, Yu Feng Chen, Mamatjan Tursun
Abstract: In this paper, based on survey data of delays on intersections in urban highways and in accordance with theoretical capacity of each traffic lane, various reasons of delay in intersections are analyzed numerically. A discrete traffic model to simulate traffic in intersections using Gaussian mesh method is built. After modifying intersection properties, weight of each factor in terms of their effect to capacity is acquired. An optimized way to solve traffic delay is hereby recommended.
1170
Authors: Anatoly Lukashevich
Abstract: Here computational models of contact of elastic systems with the contact finite elements (CFE) in a 2D or 3D frame-rod systems are reviewed. The solution is based on the method of the step-by-step analysis taking into account the character of loading, the complicated conditions of the contact and other factors consideration of which approaches the calculation circuit of the task to the real operating conditions of any structures or construction
2264
Authors: Josef Květoň, Jan Eliáš
Abstract: Concrete fracture can be simulated in static regime, however, it is a dynamical process. For very slow loading rates, the kinetic energy is negligible compared to the energy dissipated by fracturing, and the influence of inertia can be neglected. In all other cases, neglecting the influence of inertia forces can lead to improper results. With increasing loading rate, increase in strength and energy dissipation as well as changes in crack pattern can be observed. The contribution presents dynamical simulations of experiments on concrete specimens under various displacement rates, from very slow, quasi-static, to high displacement rates. The simulations are calculated using discrete particle model, the material is represented by a system of interconnected ideally rigid polyhedral particles. The solution of equations of motion is calculated using implicit time integration Newmark scheme. The constitutive behavior of the material is strain rate independent. For high strain rates the influence of inertia forces dominates and is mainly responsible for increase in loading forces as well as for change in the crack pattern and crack branching. The results obtained with the model are compared to experimental data from literature.
345
Authors: Martin Kalina, Zdenek Kala, Petr Frantik
Abstract: The article deals with the computational model of an elastic von Mises planar truss. The description of a mathematical concept, which is intended for the creation of computational programmes based on a finite number of segments, is presented. The mathematical solution is suitable for the analysis of load-deflection curves. Structural deformation is evaluated by seeking the minimal potential energy. The article examines the effects of change in the vertical displacement of the top joint on strut axes. The step by step incremental method is used in combination with the Newton-Raphson method. The presented study is aimed at the evaluation of the force in the bifurcation point, which determines the moment when loading of the model causes passing from the pre-critical effect (attainment of maximum vertical load action) to the post-critical effect. Symmetric and asymmetric initial axis imperfections are considered and relevant symmetric and asymmetric shapes of buckling are identified. The stability problem of the von Mises truss is discussed in connection with the random effects of imperfections.
49
Authors: Anatoly Lukashevich, Leonid Rozin
Abstract: Here computational models of contact of elastic systems with the contact finite elements (CFE) in a 2D or 3D frame-rod systems are reviewed. The solution is based on the method of the step-by-step analysis taking into account the character of loading, the complicated conditions of the contact and other factors consideration of which approaches the calculation circuit of the task to the real operating conditions of any structures or construction
2932
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