A Study of Three Intrinsic Problems of the Classic Discrete Element Method Using Flat-Joint Model

Wu, She–Ching; Xu, Xueliang

doi:10.1007/s00603-015-0890-z

Cited by 204 publications

(75 citation statements)

References 43 publications

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“…Secondly, parameters of both Mohr‐Coulomb and Hoek‐Brown strength envelops obtained from simulation are quite close to those derived from physical experiments. Only a very few studies have reported a good match in all these properties listed in Table . Therefore, these two features increase the confidence of the application of the flat‐joint contact model to simulate the behavior of natural hard rock.…”

Section: Comparison With Standard Laboratory Testsmentioning

confidence: 73%

“…Two inherent shortages have been identified from these materials upon comparing with real properties of hard rocks—BPM materials produce a lower ratio of uniaxial compressive strength (UCS) to tensile strength and a lower friction angle of the failure envelope . To overcome these two shortages, some new logics or contact models, such as clump method, grain‐based model, flat‐jointed model, and enhanced bonded‐particle material, have been proposed and applied . Although flat‐jointed model is relatively easier to build among these methods, it may need more time to test the model since a flat‐joint contact usually contains four or even more segments in order to obtain reliable results …”

Section: Introductionmentioning

confidence: 99%

“…First, studies on both mechanical properties and fracturing behavior of a rock with the application of the flat‐joint contact are limited. Most previous studies have focused on investigating mechanical properties of flat‐jointed materials or examined parameters or factors influencing those mechanical properties . Second, although mimicking the microstructure of rock is regarded as an outstanding strength of PFC, systematic studies in this aspect are rare .…”

Section: Introductionmentioning

confidence: 99%

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A study on mechanical properties and fracturing behavior of Carrara marble with the flat‐jointed model

Cheng

Wong

2020

Num Anal Meth Geomechanics

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Summary Overcoming two inherent limitations presented by the standard bonded‐particle model (BPM), the flat‐jointed model still lacks extensive application. This study hereby conducts a comprehensive investigation on the application of the flat‐jointed model in rock mechanics study. First, after a careful examination on the mechanical behavior of the flat‐joint contact, a systematic calibration has been conducted to build numerical models matching the mechanical properties of Carrara marble. Second, the validated model is used to simulate the fracturing behavior of marble specimens containing a single or en‐echelon flaws. Finally, the appearance of particle flow code (PFC) models has been compared with the results obtained from optical observation in order to establish a possible correlation between PFC models and real marble regarding microcracking behavior. Discussions suggest that to remove the particle size effect, the model resolution (ratio of sample dimension to the average particle diameter) should be larger than 30 in the flat‐jointed model and 150 in the BPM, respectively. Results from the above investigations suggest that the flat‐jointed model is capable of matching both the mechanical properties and fracturing behavior of Carrara marble. The numerical model is more reliable to predict the fracturing path at the instant of initiation than at failure. Development of initial fractures is not only controlled by the magnitude of tension force but also influenced by the extent of distribution of tension force. The appearance and components of a fracture in flat‐jointed models probably reveal not only its property (tensile or shear) but also the corresponding microcracking behavior of real rocks.

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Section: Comparison With Standard Laboratory Testsmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A study on mechanical properties and fracturing behavior of Carrara marble with the flat‐jointed model

Cheng

Wong

2020

Num Anal Meth Geomechanics

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“…In this study, the half-cylinder and cylinder specimens of the numerical model were built through the flat-joint model (FJM) in DEM [29]. e flatjoint model could be applied to hard rock by introducing a polygonal grain structure to provide rotational restraint arising from intergranular interlock [29][30][31].…”

Section: Contact Modelsmentioning

confidence: 99%

Point Load Test of Half-Cylinder Core Using the Numerical Model and Laboratory Tests: Size Suggestion and Correlation with Cylinder Core

Ren

Liu

et al. 2018

Advances in Civil Engineering

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The point load test (PLT) is intended as an index test for rock strength classification or estimations of other strength parameters because it is economical and simple to conduct in the laboratory and in field tests. In the literature, calculation procedures for cylinder cores, blocks, or irregular lumps can be found, but no study has researched such procedures for half-cylinder cores. This paper presents the numerical model and laboratory tests for half-cylinder and cylinder specimens. The results for half-cylinder and cylinder specimens are then presented, analysed, and discussed. A correlation of failure load between half-cylinder and cylinder specimens is established with a suitable size suggestion and correction factor. It is found that the failure load becomes stable when half-cylinder specimens have a length/diameter ratio higher than 0.9. In addition, the results show that the point load strength index (PLSI) of half-cylinder cores can be calculated using the calculation procedures for diametral testing on cylinder cores, and it is necessary to satisfy the conditions that the length/diameter ratio be higher than 0.9 and the failure load be multiplied by 0.8.

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“…The resulting assembly is able to not only possess elastic properties, but also maintains plastic properties which can generate fractures when bonds between these particles break. Although the standard bonded-particle model (BPM) has been successfully applied to solve a wide range of problems, there are still some intrinsic problems that cannot be avoided using the standard BPM, such as an unrealistically low unconfined compressive strength to tensile strength (UCS/UTS) ratio, an excessively low internal friction angle, and a linear envelope [22]. In order to avoid those problems in the simulating process, it is decided to apply the flat-joint model to model soda-lime glass.…”

Section: Dem Model Of Soda-lime Glassmentioning

confidence: 99%

Discrete Element Simulation of Orthogonal Machining of Soda-Lime Glass

Yang

Alkotami

Lei

2018

JMMP

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Transparent, brittle materials, like glass, are used in various applications due to their advantages of mechanical and optical properties. However, their hard and brittle nature causes significant challenges to researchers when they design and test a new machining process. In order to optimize this time-consuming process, discrete element method (DEM) is applied to simulate the cutting process of soda-lime glass in this study. The first step is to create a synthetic material that behaves like soda-lime glass. Then, the macroproperties are calibrated by adjusting the microparameters of the DEM model to match the mechanical properties of the real soda-lime glass. Finally, orthogonal machining simulations are conducted and model validation are conducted by comparing the predicted cutting forces with those from the orthogonal cutting experiments.

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A Study of Three Intrinsic Problems of the Classic Discrete Element Method Using Flat-Joint Model

Cited by 204 publications

References 43 publications

A study on mechanical properties and fracturing behavior of Carrara marble with the flat‐jointed model

A study on mechanical properties and fracturing behavior of Carrara marble with the flat‐jointed model

Point Load Test of Half-Cylinder Core Using the Numerical Model and Laboratory Tests: Size Suggestion and Correlation with Cylinder Core

Discrete Element Simulation of Orthogonal Machining of Soda-Lime Glass

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