Discrete element method to model cracking for two layer systems

TAPPI Journal ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 101-108
Author(s):  
Daniel Varney ◽  
Douglas Bousfield
Keyword(s):  
Discrete Element Method ◽  
Flexural Modulus ◽  
Single Layer ◽  
Discrete Element ◽  
Flexural Stress ◽  
Layer System ◽  
Three Point Bending ◽  
Moving Force ◽  
Coating Layers ◽  
Element Method

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.

scholarly journals Parametric Study on Strength Characteristics of Two-Dimensional Ice Beam Using Discrete Element Method

2021 ◽  
Vol 11 (18) ◽  
pp. 8409
Author(s):  
Seongjin Song ◽  
Wooyoung Jeon ◽  
Sunho Park
Keyword(s):  
Bond Strength ◽  
Discrete Element Method ◽  
Strength Criterion ◽  
Discrete Element ◽  
Strength Characteristics ◽  
Two Dimensional ◽  
Three Point Bending ◽  
Local Parameters ◽  
Compressive Tests ◽  
Element Method

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.

Discrete element method to predict coating failure mechanisms

TAPPI Journal ◽  
2018 ◽  
Vol 17 (01) ◽  
pp. 21-28 ◽  
Author(s):  
Daniel Varney ◽  
Douglas Bousfield
Keyword(s):  
Flexural Modulus ◽  
Failure Mechanisms ◽  
Discrete Element ◽  
Three Point Bending ◽  
Moving Force ◽  
Coating Failure ◽  
Out Of Plane ◽  
Particle Level ◽  
Force Velocity ◽  
Discrete Element Methods

The mechanical properties of coating layers are critical for post-application processes such as calendering, printing, and folding. Discrete element methods (DEM) have been used to simulate basic deformations such as tensile and compression, but have not been used as a tool to predict cracking-at-the-fold (CAF) or picking. DEM has the potential to increase our understanding of these failure mechanisms at the particle level. We propose a method to model the three-point bending of a coating layer and also the out-of-plane picking event during printing (using a z-direction scenario and an approach involving a moving force/velocity). Properties of the binder and the binder concentration are input parameters for the simulation. The model predicts the crack formation of the layer, the flexural modulus, and the maximum flexural strain during bending. The model also predicts the forces required for picking to occur. Results are compared with those of complimentary studies.

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
Keyword(s):  
Discrete Element Method ◽  
Discrete Element ◽  
Point Of View ◽  
Bending Tests ◽  
Three Point Bending ◽  
Deformation Stage ◽  
Initiation And Propagation ◽  
Discontinuous Deformation ◽  
Sawing Process ◽  
Element Method

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.

scholarly journals Two-Layer Red Blood Cell Membrane Model Using the Discrete Element Method

2016 ◽  
Vol 846 ◽  
pp. 270-275
Author(s):  
Sarah Barns ◽  
Emilie Sauret ◽  
Suvash Saha ◽  
Robert Flower ◽  
Yuan Tong Gu
Keyword(s):  
Blood Cell ◽  
Discrete Element Method ◽  
Red Blood Cell ◽  
Numerical Models ◽  
Single Layer ◽  
Discrete Element ◽  
Reduction Ratio ◽  
Shape Variation ◽  
Layer Model ◽  
Element Method

The red blood cell (RBC) membrane consists of a lipid bilayer and spectrin-based cytoskeleton, which enclose haemoglobin-rich fluid. Numerical models of RBCs typically integrate the two membrane components into a single layer, preventing investigation of bilayer-cytoskeleton interaction. To address this constraint, a new RBC model which considers the bilayer and cytoskeleton separately is developed using the discrete element method (DEM). This is completed in 2D as a proof-of-concept, with an extension to 3D planned in the future. Resting RBC morphology predicted by the two-layer model is compared to an equivalent and well-established composite (one-layer) model with excellent agreement for critical cell dimensions. A parametric study is performed where area reduction ratio and spring constants are varied. It is found that predicted resting geometry is relatively insensitive to changes in spring stiffness, but a shape variation is observed for reduction ratio changes as expected.

scholarly journals Model Establishment of a Co-Based Metal Matrix with Additives of WC and Ni by Discrete Element Method

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2319 ◽  
Author(s):  
Xiuyu Chen ◽  
Guoqin Huang ◽  
Yuanqiang Tan ◽  
Hui Huang ◽  
Hua Guo ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Metal Matrix ◽  
Rupture Strength ◽  
Experimental Tests ◽  
Discrete Element ◽  
Calibration Procedure ◽  
Prediction Ability ◽  
Three Point Bending ◽  
Dem Model ◽  
Element Method

A metal matrix is an indispensable component of metal-bonded diamond tools. The composition design of a metal matrix involves a number of experiments, making costly in terms of time, labor, and expense. The discrete element method (DEM) is a potential way to relieve these costs. The aim of this work is to demonstrate a methodology for establishing and calibrating metal matrix’s DEM model. A Co-based metal matrix with WC and Ni additives (CoX–WC–Ni) was used, in which the Co-based metal was Co–Cu–Sn metal (CoX). The skeletal substances in the metal matrix were treated as particles in the model, and the bonding substances were represented by the parallel bond between particles. To describe the elasticity of the metal matrix, a contact bond was also loaded between particles. A step-by-step calibration procedure with experimental tests of three-point bending and compression was proposed to calibrate all microcosmic parameters involved during the establishment of DEM models: first for the CoX matrix, then for the CoX–WC matrix and CoX–Ni matrix, and finally for the CoX–WC–Ni matrix. The CoX–WC–Ni DEM model was validated by the transverse rupture strength (TRS) of two new compositions and the results indicated that the model exhibited a satisfactory prediction ability with an error rate of less than 10%.

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