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Full-Text Articles in Social and Behavioral Sciences
Micromechanics-Based Investigation Of Fouled Ballast Using Large-Scale Triaxial Tests And Discrete Element Modeling, Ngoc Trung Ngo, Buddhima Indraratna, Cholachat Rujikiatkamjorn
Micromechanics-Based Investigation Of Fouled Ballast Using Large-Scale Triaxial Tests And Discrete Element Modeling, Ngoc Trung Ngo, Buddhima Indraratna, Cholachat Rujikiatkamjorn
Faculty of Engineering and Information Sciences - Papers: Part A
Railway ballast comprises unbounded discrete grains that are often used to form a load-bearing platform for tracks. Ballast degradation as trains pass over the tracks and infiltration of external fines including slurried (pumped) fine subgrade soils are two of the main reasons for ballast fouling. Fouling causes tracks to settle and also reduces the load-bearing capacity, which is associated with a reduction in internal friction and increased lateral spreading of the ballast layer. This paper presents a study of mobilized friction angle, volumetric behavior, and associated evolutions of contact and fabric anisotropy of fouled ballast subjected to monotonic triaxial loading …
Modeling Behaviour Of Railway Ballast In Prismoidal Apparatus Using Discrete Element Method, Gino O. Calderon Vizcarra, Sanjay Nimbalkar, Michele Dal Toe Casagrande
Modeling Behaviour Of Railway Ballast In Prismoidal Apparatus Using Discrete Element Method, Gino O. Calderon Vizcarra, Sanjay Nimbalkar, Michele Dal Toe Casagrande
Faculty of Engineering and Information Sciences - Papers: Part A
This article presents the results of numerical simulations of loading tests conducted on coarse particles that simulate railroad ballast. The objective of this study was to evaluate the deformation of ballast under vertical loading and to study the influence of the two different particle size distributions. One of them was according to particle size distribution recommended by Indraratna and co-workers in the past as an improvement to Australian Standard and the other was prepared in accordance with Brazilian standard. The discrete element method offers a new means of studying the response characteristics of railway ballast. The basic idea of discrete …
Finite Element Method Analysis Of Surface Roughness Transfer In Micro Flexible Rolling, Feijun Qu, Haibo Xie, Zhengyi Jiang
Finite Element Method Analysis Of Surface Roughness Transfer In Micro Flexible Rolling, Feijun Qu, Haibo Xie, Zhengyi Jiang
Faculty of Engineering and Information Sciences - Papers: Part A
Micro flexible rolling aims to fabricate submillimeter thick strips with varying thickness profile, where the surface quality of products is mainly determined by initial workpiece surface roughness and subsequent surface asperity flattening process, which is affected by process parameters during rolling. This paper shows a 3D finite element model for flexible rolling of a 250 μm thick workpiece with reduction of 20 to 50%, and rolling phase with thinner thickness indicates a better ability to decrease the surface roughness. Four types of initial workpiece surface roughness are studied in the simulation, and the influences of process parameters, such as friction …
Coupled Discrete Element-Finite Difference Method For Analysing The Load-Deformation Behaviour Of A Single Stone Column In Soft Soil, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn, Scott W. Sloan
Coupled Discrete Element-Finite Difference Method For Analysing The Load-Deformation Behaviour Of A Single Stone Column In Soft Soil, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn, Scott W. Sloan
Faculty of Engineering and Information Sciences - Papers: Part A
Experimental studies and numerical modelling of the deformation of soft clay stabilised by stone columns have been conducted over the past few decades. Continuum-based numerical models have provided valuable insight into the prediction of settlement, lateral deformation, and stress and strain-rate dependent behaviour of stone columns at a macroscopic scale, but because they consist of granular material such as crushed rock, gravel, and waste rock aggregates, their behaviour is influenced by inter-particle micromechanics and cannot be modelled properly using these models. In this paper a novel coupled model of the discrete element method (DEM) and finite difference method (FDM) is …
A Study Of The Behaviour Of Fresh And Coal Fouled Ballast Reinforced By Geogrid Using The Discrete Element Method, Ngoc Trung Ngo, Buddhima Indraratna, Cholachat Rujikiatkamjorn
A Study Of The Behaviour Of Fresh And Coal Fouled Ballast Reinforced By Geogrid Using The Discrete Element Method, Ngoc Trung Ngo, Buddhima Indraratna, Cholachat Rujikiatkamjorn
Faculty of Engineering and Information Sciences - Papers: Part A
Geogrids are widely used in ballasted rail tracks for reinforcement and stabilisation. During train operation, ballast becomes contaminated or fouled due to infiltration of fines from the surface, mud pumping from the subgrade, and degradation, which decreases the performance of the geogrids. This paper presents the results of a laboratory and numerical simulation to study the effect that coal fines have on the interface between ballast and geogrid. The stress-strain behaviour of fresh and fouled ballast reinforced by geogrid was investigated via a series of large scale direct shear tests in the laboratory and numerical simulations using the Discrete Element …
Effect Of Mesh On Springback In 3d Finite Element Analysis Of Flexible Microrolling, Feijun Qu, Zhengyi Jiang, Haina Lu
Effect Of Mesh On Springback In 3d Finite Element Analysis Of Flexible Microrolling, Feijun Qu, Zhengyi Jiang, Haina Lu
Faculty of Engineering and Information Sciences - Papers: Part A
In flexible microrolling, springback in thickness direction is a critical indicator to determine the forming quality. Accurate prediction of springback is one of the significant aspects in the finite element analysis of flexible microrolling. Meshing is a step of great importance in finite element analysis of manufacturing process as it directly determines the accuracy of the FEA results as well as the requested computational time. This paper presents a numerical study on revealing the mesh effects on the accuracy of springback estimation utilising ABAQUS/Standard for modelling and analyses. Two types of meshes with six mesh sizes for each mesh type …
Study On Surface Asperity Flattening In Cold Quasi-Static Uniaxial Planar Compression By Crystal Plasticity Finite Element Method, Hejie Li, Zhengyi Jiang, Dongbin Wei, Jianzhong Xu, Xiaoming Zhang, Dianyao Gong, Jingtao Han
Study On Surface Asperity Flattening In Cold Quasi-Static Uniaxial Planar Compression By Crystal Plasticity Finite Element Method, Hejie Li, Zhengyi Jiang, Dongbin Wei, Jianzhong Xu, Xiaoming Zhang, Dianyao Gong, Jingtao Han
Faculty of Engineering and Information Sciences - Papers: Part A
In order to study the surface asperity flattening in a quasi-static cold uniaxial planar compression, the experimental results of atomic force microscope and electron backscattered diffraction have been employed in a ratedependent crystal plasticity model to analyze this process. The simulation results show a good agreement with the experimental results: in this quasi-static deformation process, lubrication can hinder the surface asperity flattening process even under very low deformation rate. However, due to the limitation of the model and some parameters, the simulation results cannot predict all the properties in detail such as S orientation {123}and the maximum stress in sample …
Finite Element Method Analysis Of Micro Cross Wedge Rolling Of Metals, Zhengyi Jiang, Haina Lu, Dongbin Wei, Kezhi Linghu, Xianming Zhao, Xiaoming Zhang, Di Wu
Finite Element Method Analysis Of Micro Cross Wedge Rolling Of Metals, Zhengyi Jiang, Haina Lu, Dongbin Wei, Kezhi Linghu, Xianming Zhao, Xiaoming Zhang, Di Wu
Faculty of Engineering and Information Sciences - Papers: Part A
A newly developed manufacturing technology - micro cross wedge rolling technology is an appropriate method to produce micro axisymmetric components such as micro stepped shafts. The development of this classic cold forming process is limited by a lack of sufficient understanding of geometric and material effects due to the size reduction of the components. In this study, a numerical model is proposed to simulate micro cross wedge rolling where the grain size effect is taken into account. Pure copper is chosen as the raw material. A finite element simulation is implemented where the diameter of the cylindrical workpiece is 0.8 …
A Study Of Plastic Deformation Behavior During High Pressure Torsion Process By Crystal Plasticity Finite Element Simulation, Peitang Wei, Cheng Lu, A K. Tieu, Guanyu Deng
A Study Of Plastic Deformation Behavior During High Pressure Torsion Process By Crystal Plasticity Finite Element Simulation, Peitang Wei, Cheng Lu, A K. Tieu, Guanyu Deng
Faculty of Engineering and Information Sciences - Papers: Part A
High pressure torsion (HPT) is an efficient technique of producing ultrafine grained materials with exceptional small grain size. In this study, a crystal plasticity finite element method (CPFEM) model has been developed to investigate the plastic deformation behavior of pure aluminum single crystal during the HPT process. The simulation results show that, the distribution and evolution of the macroscopic plastic strain and the accumulative shear strain are similar. The value increases with the increase of the distance from the center as well as the number of revolution. The simulation is capable of reflecting the anisotropic characteristics of HPT deformation, a …
Behavior Of Fresh And Fouled Railway Ballast Subjected To Direct Shear Testing: Discrete Element Simulation, B Indraratna, N T Ngo, C Rujikiatkamjorn, J S. Vinod
Behavior Of Fresh And Fouled Railway Ballast Subjected To Direct Shear Testing: Discrete Element Simulation, B Indraratna, N T Ngo, C Rujikiatkamjorn, J S. Vinod
Faculty of Engineering and Information Sciences - Papers: Part A
This paper presents the three-dimensional discrete element method (DEM) that was used to study the shear behaviour of fresh and coal fouled ballast in direct shear testing. The volumetric changes and stress-strain behaviour of fresh and fouled ballast were simulated and compared with the experimental results. 'Clump logic' in Particle Flow Code (PFC3D) incorporated in a MATLAB Code was used to simulate irregular shaped particles in which groups of ten to twenty spherical balls were clumped together in appropriate sizes to simulate ballast particles. Fouled ballast with various Void Contaminant Index (VCI), ranging from 20%VCI to 70%VCI, were modelled by …
Finite Element Analysis Of Roll Bit Behaviors In Cold Foil Rolling Process, Liang Hao, Zhengyi Jiang, Dongbin Wei, Xiawei Cheng
Finite Element Analysis Of Roll Bit Behaviors In Cold Foil Rolling Process, Liang Hao, Zhengyi Jiang, Dongbin Wei, Xiawei Cheng
Faculty of Engineering and Information Sciences - Papers: Part A
To investigate roll bite behaviors in cold foil rolling process, a 2D elasto-plastic finite model is established using FEM software ABAQUS. Contact pressure distribution and roll contour in roll bite are also presented, which demonstrate that foil rolling process is different from conventional strip rolling process. The contact area is composed of entry elastic zone, entry plastic zone, an extensive neutral zone, exit plastic zone and exit elastic zone. It conforms to the results of Fleck foil rolling theory. Elastic deformation and work hardening of foil in roll bite are taken into account. The effect of rolling parameters, such as …
Simplified Boundary Element Method For Kinematic Response Of Single Piles In Two-Layer Soil, Fayun Liang, Haibing Chen, Wei Dong Guo
Simplified Boundary Element Method For Kinematic Response Of Single Piles In Two-Layer Soil, Fayun Liang, Haibing Chen, Wei Dong Guo
Faculty of Engineering and Information Sciences - Papers: Part A
A simple approach is formulated to predict the elastic, kinematic pile bending during harmonic or transient excitation for a circular pile (rather than a simplified thin strip). The kinematic response of a pile embedded in two-layer soil is resolved in the frequency domain caused by the upward propagation of shear waves from the underlying bedrock. The simplified approach is generally valid to nonhomogeneous soil profiles, in light of the good comparison with the dynamic FE method and BDWF solution. It employs the soil-displacement-influence coefficients Is to consider the pile-soil interaction (resembling the spring constant kx in the BDWF) and provides …
Effect Of Particle Properties On The Discrete Element Simulation Of Wall Friction, Andrew Grima, Peter Wypych
Effect Of Particle Properties On The Discrete Element Simulation Of Wall Friction, Andrew Grima, Peter Wypych
Faculty of Engineering and Information Sciences - Papers: Part A
Modelling the interaction between particles and boundaries is of great interest and importance in many Discrete Element Method (DEM) applications where boundary failure conditions dictate the flow behaviour and velocity gradients of a bulk material. Bulk wall friction angles in DEM models are dependent on the mechanical properties of the particles and boundary material as well as the constraints of the contact models used, especially the tangential and rolling torque components. This paper examines the parameters determined from the calibration inclination test by conducting direct wall shear tests to validate the accuracy of the calibration parameters and the sensitivity of …
Finite Element Modelling Of Surface Roughness Transfer And Oxide Scale Micro Deformation In Metal Manufacturing Process, Zhengyi Jiang, Dongbin Wei, Hejie Li
Finite Element Modelling Of Surface Roughness Transfer And Oxide Scale Micro Deformation In Metal Manufacturing Process, Zhengyi Jiang, Dongbin Wei, Hejie Li
Faculty of Engineering and Information Sciences - Papers: Part A
In the paper, the micro deformation of oxide scale in hot strip rolling has been investigated with considering the friction effect. The finite element simulation of the micro deformation of oxide scale has been successfully conducted, and the calculated surface roughness is compared with the measured value, which shows a good agreement. A crystal plasticity finite element method (CPFEM) model was also successfully developed to analyse the surface roughness transfer during metal manufacturing. The simulation results show a good agreement with the experimental results in the flattening of surface asperity, and the surface roughness decreases significantly with an increase of …
The Sensitivity Of Particle Parameters In Discrete Element Modelling Of Belt Conveyor Transfers, David B. Hastie, Peter W. Wypych
The Sensitivity Of Particle Parameters In Discrete Element Modelling Of Belt Conveyor Transfers, David B. Hastie, Peter W. Wypych
Faculty of Engineering and Information Sciences - Papers: Part A
As discrete element modelling (DEM) becomes more widely used as a design tool, its suitability to modelling belt conveyor applications including conveyor transfers and conveyor trajectories is becoming more recognised. The accuracy of the data inputted for both the system geometry and particle perspective are vital if the outputs obtained from DEM simulations are to be considered valid. Bench-scale testing can readily obtain a range of particle parameters, however, there are others that can be more difficult to determine. This paper focuses on two such parameters; coefficient of rolling friction and shear modulus. A series of sensitivity analyses have been …
Finite Element Analysis Of Debonding Failures In Cfrp-Strengthened Rectangular Steel Tubes Subjected To An End Bearing Load, D Fernando, T Yu, J G. Teng
Finite Element Analysis Of Debonding Failures In Cfrp-Strengthened Rectangular Steel Tubes Subjected To An End Bearing Load, D Fernando, T Yu, J G. Teng
Faculty of Engineering and Information Sciences - Papers: Part A
The end bearing capacity of a rectangular steel tube can be substantially increased through local strengthening by bonding carbon fiber reinforced polymer (CFRP) plates to the webs of the steel tube. Existing studies have revealed that failure of such a strengthened tube generally occurs by debonding of the CFRP plates from the steel tube and the effectiveness of this strengthening method depends significantly on the properties of the adhesive. This paper presents a finite element (FE) study on debonding failures in such CFRP-strengthened rectangular steel tubes subjected to an end bearing load. In the proposed FE model, a bond-slip model …
Finite Element Analysis Of Consolidation Behavior Of Composite Soft Ground, S Horpibulsuk, A Chinkulkijniwat, A Cholaphatsron, J Suebsuk, M D. Liu
Finite Element Analysis Of Consolidation Behavior Of Composite Soft Ground, S Horpibulsuk, A Chinkulkijniwat, A Cholaphatsron, J Suebsuk, M D. Liu
Faculty of Engineering and Information Sciences - Papers: Part A
Columnar inclusion is one of the effective and widely used methods for improving engineering properties of soft clay ground. This paper investigates the consolidation behavior of composite soft clay ground using both physical model tests under an axial-symmetry condition and finite element simulations using the PLAXIS 2D program. Because the soil-cement column enhances the yield stress and stiffness of the composite ground, the composite ground is in an over-consolidated state under the applied vertical applied stresses. At this state, the rate of consolidation is rapid due to a high coefficient of consolidation. The consolidation of the composite ground is mainly …
The Beginning Of A New Era In Design: Calibrated Discrete Element Modelling, Andrew Grima, David Hastie, David Curry, Peter Wypych, Richard La Roche
The Beginning Of A New Era In Design: Calibrated Discrete Element Modelling, Andrew Grima, David Hastie, David Curry, Peter Wypych, Richard La Roche
Faculty of Engineering and Information Sciences - Papers: Part A
The reliable storage and flow of bulk materials requires a comprehensive design process and good understanding of the flow properties of a bulk material. Analytical and empirical design techniques form the backbone of many design processes as they have been validated by research, however, theories based on continuum mechanics have many shortcomings and are restricted to 2-D analysis. Discrete element modelling (DEM) is proving to be a popular analysis and simulation method to verify designs for a wide range of bulk material processing and handling operations, such as transfer chutes. With the advances in computing and DEM technology, DEM has …
Discrete Element Modelling: Trouble-Shooting And Optimisation Tool For Chute Design, Andrew P. Grima, Thomas Fraser, David B. Hastie, Peter W. Wypych
Discrete Element Modelling: Trouble-Shooting And Optimisation Tool For Chute Design, Andrew P. Grima, Thomas Fraser, David B. Hastie, Peter W. Wypych
Faculty of Engineering and Information Sciences - Papers: Part A
Conveyor transfer stations play a key role in many industries that handle bulk materials. Transfer stations can be rather sensitive to changes in material properties and can lead to relentless problems regarding reliability, wear, bottlenecking and blockages. Wet and sticky ores are typically difficult to handle materials due to their obnoxious ability to form a cohesive arch, adhere to surfaces and poor flow ability. Mines that are situated in areas with seasonal high rainfalls or that have started to exploit newer and more difficult to mine and handle ores, often from below the water table, experience vast difficulty in reliably …
Contact Element Method With Two Relative Coordinates And Its Application To Prediction Of Strip Profile Of A Sendzimir Mill, Hai-Liang Yu, Xiang-Hua Liu, Gyoo-Taek Lee
Contact Element Method With Two Relative Coordinates And Its Application To Prediction Of Strip Profile Of A Sendzimir Mill, Hai-Liang Yu, Xiang-Hua Liu, Gyoo-Taek Lee
Faculty of Engineering and Information Sciences - Papers: Part A
A new numerical method, Contact Element Method with Two Relative Coordinates, has been developed. The main features of this method are that element meshing depends on the contact length between rolls or between the work roll and the strip, and that each element has two relative coordinates based on two separate contact objects. With this method, a program code “Setup Models for Sendzimir Mill” (SM4SM) has been developed for prediction of the strip profile of a 20-high Sendzimir mill with double AS-U-Roll systems. The strip profiles are predicted under various rolling conditions, such as the positions of AS-U racks, the …
A Quasi-Dynamic Nonlinear Finite Element Model To Investigate Prosthetic Interface Stresses During Walking For Trans-Tibial Amputees, Xiaohong Jia, Ming Zhang, Xiaobing Li, Winson Lee
A Quasi-Dynamic Nonlinear Finite Element Model To Investigate Prosthetic Interface Stresses During Walking For Trans-Tibial Amputees, Xiaohong Jia, Ming Zhang, Xiaobing Li, Winson Lee
Faculty of Engineering and Information Sciences - Papers: Part A
Background. To predict the interface pressure between residual limb and prosthetic socket for trans-tibial amputees during walking. Methods. A quasi-dynamic finite element model was built based on the actual geometry of residual limb, internal bones and socket liner. To simulate the friction/slip boundary conditions between the skin and liner, automated surface-to-surface contact was used. Besides variable external loads and material inertia, the coupling between the large rigid displacement of knee joint and small elastic deformation of residual limb and prosthetic components were also considered. Results. Interface pressure distribution was found to have the same profile during walking. The high pressures …
Design Of Monolimb Using Finite Element Modelling And Statistics-Based Taguchi Method, Winson Lee, Ming Zhang
Design Of Monolimb Using Finite Element Modelling And Statistics-Based Taguchi Method, Winson Lee, Ming Zhang
Faculty of Engineering and Information Sciences - Papers: Part A
Background. Monolimb is a transtibial prosthesis having the socket and shank molded into one piece of thermoplastic material. If properly designed, the shank of a monolimb can have a controlled deflection during walking which simulates the ankle joint motions to some extent. However, there is no clear guidance for the design of monolimb considering the dilemma between shank flexibility and structural integrity. Methods. Finite element analysis was used to simulate structural tests based on ISO10328 on monolimbs of different configurations. Statistics-based Taguchi method was employed to identify the significance of each design factor in controlling the deformation and stress within …
Finite Element Modeling Of Contact Interface Between Trans-Tibial Residual Limb And Prosthetic Socket, Winson Lee, Ming Zhang, Xiaohong Jia, Jason Cheung
Finite Element Modeling Of Contact Interface Between Trans-Tibial Residual Limb And Prosthetic Socket, Winson Lee, Ming Zhang, Xiaohong Jia, Jason Cheung
Faculty of Engineering and Information Sciences - Papers: Part A
Finite element method has been identified as a useful tool to understand the load transfer mechanics between a residual limb and its prosthetic socket. This paper proposed a new practical approach in modeling the contact interface with consideration of the friction/slip conditions and pre-stresses applied on the limb within a rectified socket. The residual limb and socket were modeled as two separate structures and their interactions were simulated using automated contact methods. Some regions of the limb penetrated into the socket because of socket modification. In the first step of the simulation, the penetrated limb surface was moved onto the …
Dynamic Properties And Liquefaction Behavior Of Granular Materials Using Discrete Element Method, S V. Dinesh, T G. Sitharam, J S Vinod
Dynamic Properties And Liquefaction Behavior Of Granular Materials Using Discrete Element Method, S V. Dinesh, T G. Sitharam, J S Vinod
Faculty of Engineering and Information Sciences - Papers: Part A
Dynamic properties of the soil such as shear modulus and damping ratio are important parameters in the prediction of the dynamic response of geotechnical engineering structures. Though these properties are dependent on several factors, strain amplitude and confining pressure have a major effect. Liquefaction is another important phenomenon associated with the undrained response of granular materials in loose state. In this paper, the results of the numerical simulation of cyclic triaxial shear tests on three-dimensional assembly consisting of 1000 sphere particles using Discrete Element Method (DEM) have been reported under undrained conditions. From the results, the shear modulus and damping …
The Dual Reciprocity Boundary Element Method For Magnetohydrodynamic Channel Flows, Song-Ping Zhu, Huan-Wen Liu
The Dual Reciprocity Boundary Element Method For Magnetohydrodynamic Channel Flows, Song-Ping Zhu, Huan-Wen Liu
Faculty of Engineering and Information Sciences - Papers: Part A
In this paper, we consider the problem of the steady-state fully developed magnetohydrodynamic (MHD) flow of a conducting fluid through a channel with arbitrary wall conductivity in the presence of a transverse external magnetic field with various inclined angles. The coupled governing equations for both axial velocity and induced magnetic field are firstly transformed into decoupled Poisson-type equations with coupled boundary conditions. Then the dual reciprocity boundary element method (DRBEM) [20] is used to solve the Poisson-type equations. As testing examples, flows in channels of three different cross-sections, rectangular, circular and triangular, are calculated. It is shown that solutions obtained …