Numerical Simulation of Granite Sawing by Discrete Element Method

2009 ◽  
Vol 16-19 ◽  
pp. 1283-1288
Author(s):  
Yong Ye ◽  
Yuan Li ◽  
Xi Peng Xu

Granite is a kind of typical discrete material, which experiences from continuous deformation stage, discontinuous deformation stage to fracture stage under sawing forces. Using discrete element method (DEM) to study the process of sawing granite will help us to understand the removal mechanism of granite from the microscopic point of view. In this paper, numerical uniaxial compression and three-point bending tests were conducted to determine the microscopic parameters of the granite specimen firstly, and then simulation was performed for sawing of the specimen. The sawing process, deformation characteristics of granite and the effect of initiation and propagation of cracks on fracture process of granite were investigated. The emphasis was laid on analyzing the variation of sawing forces under different sawing parameters. The simulation results agree well with that of experiments, indicating that DEM can reflect the external macroscopic change of granite by changing the internal microscopic structure. The conclusions in this study would be useful to the modeling of sawing processes and engineering applications.

TAPPI Journal ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 101-108
Author(s):  
Daniel Varney ◽  
Douglas Bousfield

Cracking at the fold is a serious issue for many grades of coated paper and coated board. Some recent work has suggested methods to minimize this problem by using two or more coating layers of different properties. A discrete element method (DEM) has been used to model deformation events for single layer coating systems such as in-plain and out-of-plain tension, three-point bending, and a novel moving force picking simulation, but nothing has been reported related to multiple coating layers. In this paper, a DEM model has been expanded to predict the three-point bending response of a two-layer system. The main factors evaluated include the use of different binder systems in each layer and the ratio of the bottom and top layer weights. As in the past, the properties of the binder and the binder concentration are input parameters. The model can predict crack formation that is a function of these two sets of factors. In addition, the model can predict the flexural modulus, the maximum flexural stress, and the strain-at-failure. The predictions are qualitatively compared with experimental results reported in the literature.


2014 ◽  
Vol 644-650 ◽  
pp. 1539-1542 ◽  
Author(s):  
Yong Zheng Ma ◽  
Ke Jian Cai ◽  
Zhan Tao Li ◽  
Jun Li

A new enhanced Discrete Element Method (EDEM) for modeling the system composed of cracked solids is developed by coupling the traditional Discontinuous Deformation Analysis method (DDA, a kind of implicit version of DEM) with Moving Least-Squares (MLS) meshfree approximation functions. Tracing crack growth inside fracturing blocks and other related capabilities are available in the postprocessing procedure at each iteration step. Some numerical examples are provided to verify this method, and it is prospective to solve stability problems of the slope with non-through joints and other fracture mechanics problems in a new way.


Author(s):  
В. В. Стаценко ◽  
О. П. Бурмістенков ◽  
Т. Я. Біла

Studying the influence of continuous centrifugal mixers design features on their smoothing ability. The methods used are discrete elements, mathematical modeling and regression analysis. The paper considers five continuous centrifugal mixers designs with conical and parabolic rotors. The mixers design features are determined, allowing to change their smoothing ability. Mathematical models of the bulk materials particles movement inside each mixer have been developed based on the discrete element method. The considered mixers reaction to a step change of the key component amount is investigated. The transients parameters are calculated and the particles average residence time in the mixer is determined. It is established that the introduction of turbulizers in the mixers design increases the particles kinetic energy, which leads to a decrease in their residence time in the mixer. Moreover, the absence of a turbulizer leads to a decrease in the mixing intensity. It was also found that the most effective way to increase the mixer smoothing ability is the introduction of additional rotors. In terms of the technological and design parameters combination, the use of mixers with a conical rotor and a turbulizer is the most effective from the point of view for increasing the smoothing ability. On the discrete element method basis, the bulk materials particles movement models in continuous centrifugal mixers of five designs have been developed. The influence of the mixers design features on their smoothing ability and average mixing time is determined. The results obtained allow us to select the appropriate mixer design according to the specified requirements for smoothing ability.


2021 ◽  
Vol 11 (18) ◽  
pp. 8409
Author(s):  
Seongjin Song ◽  
Wooyoung Jeon ◽  
Sunho Park

Strength characteristics of a two-dimensional ice beam were studied using a discrete element method (DEM). The DEM solver was implemented by the open-source discrete element method libraries. Three-point bending and uniaxial compressive tests of the ice beam were simulated. The ice beam consisted of an assembly of disk-shaped particles with a particular thickness. The connection of the ice particles was modelled using a cuboid element, which represents a bond. If the stress acting on the bond exceeded the bond strength criterion, the bond started to break, explaining the cracking of the ice beam. To find out the effect of the local parameters of the contact and bond models on the ice fracture, we performed numerical simulations for various bond Young‘s modulus of the particles, the bond strength, and the relative particle size ratio.


2007 ◽  
Vol 353-358 ◽  
pp. 2973-2976 ◽  
Author(s):  
Yu Yong Jiao ◽  
Xiu Li Zhang ◽  
Shui Lin Wang ◽  
Huo Zhen Wu

This study is to present a numerical investigation on fragmentation and perforation of concrete slab by hard projectile using discrete particle approaches. Discrete Element Method (DEM) and Discontinuous Deformation Analysis (DDA), the two representative discrete particle approaches, are employed to simulate a normal perforation of concrete slab by a hard ogival-nose shaped projectile, and the phenomena of spalling, plugging and scabbing are reproduced.


2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Viet-Dung Nguyen ◽  
Philippe Dufrénoy ◽  
Patrice Coorevits

Abstract The objective of this study focuses on the energy dissipation by friction on the interface of a braking system and the effects of roughness and granular plateaus on heat propagation. Faced with the difficulty of defining velocity accommodation and thermal partition between the two bodies in contact (disk and pad, for example,), the authors model the third body (friction) layer with circular particles detached from the pad. From a numerical point of view, this paper proposes a strategy of storing mechanical calculations in steady-state and using it for successive thermal processing in discrete element method (DEM) code. Thus, the heat is generated due to interparticle friction and is dissipated in the disk/pad interface by conductance. Accordingly, this coupling micro–macro model aims to determine the temperature rise of the pad/disk interface and to identify the equivalent thermal resistance. In line with that, the authors provide discussions of these parameters compared to experimental/empirical data as reported in the literature review and limitations of the model.


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