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An extended arbitrary lagrangian-eulerian finite element model (X-ALE-FEM) in large plasticity deformations
, Article MATERIALS PROCESSING AND DESIGN; Modeling, Simulation and Applications - NUMIFORM '07: 9th International Conference on Numerical Methods in Industrial Forming Processes, Porto, 17 June 2007 through 21 June 2007 ; Volume 908 , 2007 , Pages 1495-1500 ; 0094243X (ISSN) ; Anahid, M ; Shahim, K ; Sharif University of Technology
2007
Abstract
In this paper, a new computational technique is presented based on the eXtended Arbitrary Lagrangian-Eulerian Finite Element Model (X-ALE-FEM) in large plasticity deformations. An arbitrary Lagrangian-Eulerian (ALE) technique is employed to capture the advantages of both Lagrangian and Eulerian methods and alleviate the drawbacks of the mesh distortion in Lagrangian formulation. In order to remove the limitation of the mesh conforming to the boundary conditions in the simulation, the extended finite element method (X-FEM) is implemented by incorporating discontinuous fields through a partition of unity method. The implementation of X-FEM technique in the framework of ALE model is finally...
Behaviour of metal powders during cold and warm compaction
, Article Powder Metallurgy ; Volume 49, Issue 3 , 2006 , Pages 281-287 ; 00325899 (ISSN) ; Veltl, G ; Sharif University of Technology
2006
Abstract
An instrumented die was used to investigate the behaviour of metal powders during cold (ambient temperature) and warm (up to 140°C) compaction. This instrument enables simultaneous measurement of density, die wall friction coefficient, the triaxial stresses acting on the powder during the course of compaction and ejection pressure. Commercial iron, titanium, aluminium, 316L stainless steel (SS) and aluminium-silicon powders were employed for investigation. The results demonstrated the advantages of powder preheating on the compaction behaviour of metal powders concerning green density, dimensional changes, frictional behaviour, ejection characteristics and compactibiiity. However, the...
Study of the densification of a nanostructured composite powder. part 1: effect of compaction pressure and reinforcement addition
, Article Materials Science and Engineering A ; Volume 486, Issue 1-2 , 2008 , Pages 580-584 ; 09215093 (ISSN) ; Farnoush, H ; Salahi, E ; Pourazrang, K ; Sharif University of Technology
2008
Abstract
The compressibility behavior of Al-AlN nanostructured composite powder with different amount of reinforcement content was studied. The composite powder was synthesized by blending and high-energy milling process for 25 h. Williamson-Hall method was applied to determine the crystallite size after milling process. To investigate the role of reinforcement particles in consolidation of composite powders, monolithic aluminum powder was examined. Samples were made at different pressures and relationships were established between the compaction pressure and the density of the compacts. The modified Heckel equation was used to assume the pressure effect on yield strength and then was compared with...
Implementation of a high-order compact finite-difference lattice Boltzmann method in generalized curvilinear coordinates
, Article Journal of Computational Physics ; Vol. 267 , 2014 , Pages 28-49 ; ISSN: 00219991 ; Ezzatneshan, E ; Sharif University of Technology
Abstract
In this work, the implementation of a high-order compact finite-difference lattice Boltzmann method (CFDLBM) is performed in the generalized curvilinear coordinates to improve the computational efficiency of the solution algorithm to handle curved geometries with non-uniform grids. The incompressible form of the discrete Boltzmann equation with the Bhatnagar-Gross-Krook (BGK) approximation with the pressure as the independent dynamic variable is transformed into the generalized curvilinear coordinates. Herein, the spatial derivatives in the resulting lattice Boltzmann (LB) equation in the computational plane are discretized by using the fourth-order compact finite-difference scheme and the...
A comprehensive investigation into the effect of water to cement ratio and powder content on mechanical properties of self-compacting concrete
, Article Construction and Building Materials ; Vol. 57 , April , 2014 , pp. 69-80 ; ISSN: 09500618 ; Beygi, M. H. A ; Kazemi, M. T ; Vaseghi Amiri, J ; Rabbanifar, S ; Rahmani, E ; Rahimi, S ; Sharif University of Technology
Abstract
Self compacting concrete (SCC), as an innovative construction material in concrete industry, offers a safer and more productive construction process due to favorable rheological performance which is caused by SCC's different mixture composition. This difference may have remarkable influence on the mechanical behavior of SCC as compared to normal vibrated concrete (NVC) in hardened state. Therefore, it is vital to know whether the use of all assumptions and relations that have been formulated for NVC in current design codes are also valid for SCC. Furthermore, this study presents an extensive evaluation and comparison between mechanical properties of SCC using current international codes and...
Pure-injectivity of tensor products of modules
, Article Algebra Colloquium ; Vol. 21, issue. 1 , 2014 , pp. 151-156 ; ISSN: 10053867 ; Torrecillas, B ; Tousi, M ; Yassemi, S ; Sharif University of Technology
Abstract
A classical question of Yoneda asks when the tensor product of two injective modules is injective. A complete answer to this question was given by Enochs and Jenda in 1991. In this paper the analogue question for pure-injective modules is studied
The effect of aging on the fracture characteristics and ductility of self-compacting concrete
, Article Materials and Design ; Volume 55 , March 2014 , Pages 937-948 ; Kazemi, M. T ; Nikbin, I. M ; Vaseghi Amiri, J ; Sharif University of Technology
Abstract
Good knowledge of fracture parameters and cracking behavior of self-compacting concrete (SCC) from early ages until the SCC becomes mature plays an important role in design of SCC structure and also in evaluation of durability and consequently prevention of damage. In this paper, variation of fracture parameters and corresponding ductility behavior of SCC at different ages (e.g. 3days, 7days, 28days and 90days) for SCC mixes with w/c ratios of 0.45 and 0.65 have been experimentally studied. To do so, three-point bending tests were carried out on 120 notched beams. Then, size effect method (SEM) and work of fracture method (WFM) were applied to interpret the results. The results of analyses...
A plasticity model for powder compaction processes
, Article European Congress on Computational Methods in Applied Sciences and Engineering, ECCOMAS 2004, Jyvaskyla, 24 July 2004 through 28 July 2004 ; 2004 ; Mofid, M ; Khoei, A. R ; Sharif University of Technology
2004
Abstract
An endochronic constitutive model for cold powder compaction processes is developed. Although the concept of yield surface has not been explicitly assumed in the endochronic theory, it is demonstrated that the cone-cap yield surface can be derived as a special case of the proposed endochronic model. The plastic flow rule and the dilatancy condition of the model are derived and a procedure for calibration of the material parameters of the constitutive model is proposed. Since large deformations are observed in powder compaction processes, the endochronic constitutive model based on large strain plasticity is presented and an integration scheme for the rate constitutive equations is...
A constitutive model for finite deformation of endochronic plasticity in powder forming processes
, Article Journal of Materials Processing Technology ; Volume 153-154, Issue 1-3 , 2004 , Pages 12-19 ; 09240136 (ISSN) ; Bakhshiani, A ; Sharif University of Technology
2004
Abstract
In this paper, an endochronic constitutive model is developed for cold powder compaction processes. As large deformations are observed in powder forming processes, the endochronic constitutive model based on large strain plasticity is presented and an integration scheme for the rate constitutive equations is established. Although the concept of yield surface has not been explicitly assumed in the endochronic theory, it is demonstrated that the cone-cap yield surface can be derived as a special case of the proposed endochronic model. The plastic flow rule and the dilatancy condition of the model are derived and a procedure for calibration of material parameters of the constitutive model is...
Application of a failure analysis to powder forming processes
, Article Journal of Materials Processing Technology ; Volume 143-144, Issue 1 , 2003 , Pages 46-51 ; 09240136 (ISSN) ; Sharif University of Technology
2003
Abstract
In this paper, an h-adaptive analysis for the mixed finite element solution of powder forming problems is presented involving localization due to material instability. A remeshing strategy is employed to compute the distribution of required element size using the estimated error distribution. Once the new element size and its alignment have been indicated, an automated procedure is used to construct the mesh according to a predetermined size and elongation distribution. The numerical results were obtained for a multi-level component to indicate the failure surfaces and evaluate the ultimate capacity of material. © 2003 Elsevier Science B.V. All rights reserved
Methods of reducing magnetic field near the transmission lines
, Article Amirkabir (Journal of Science and Technology) ; Volume 14, Issue 55 A , 2003 , Pages 610-630 ; 10150951 (ISSN) ; Porkar, S ; Vahidi, B ; Sharif University of Technology
2003
Abstract
Due to biological effects of magnetic fields of high voltage transmission lines and induceed effects on gas pipe line, telecommunication system and inteference with sensitive electronic equipment, many effort have been done to reduce transmission lines magnetic fields and several ideas have been introduced. In this paper we review three methods: phase split, shielded and compacted line methods. With aid of a developed software programme these methods are then applied to transmission lines and the results are analyzed
Investigation of warm compaction and sintering behaviour of aluminium alloys
, Article Powder Metallurgy ; Volume 46, Issue 2 , 2003 , Pages 159-164 ; 00325899 (ISSN) ; Veltl, G ; Sharif University of Technology
IOM Communications Ltd
2003
Abstract
The effects of warm compaction on the green density and sintering behaviour of aluminium alloys were investigated. Particular attention is paid to prealloyed powders, i.e. eutectic and hypereutectic Al-Si alloys, regarding their potential applications in the automotive industry. The effects of chemical composition, alloying method, compacting temperature and the amount of powder lubricant were studied. The compaction behaviour was examined by an instrumented die enabling simultaneous measurement of density, die wall friction coefficient, the triaxial stresses acting on the powder during the course of compaction and ejection pressure. The sintering behaviour was studied via dilatometeric...
Numerical Simulation of Powder Compaction Processes Using an Endochronic Theory in Finite Plasticity Model
, Article International Journal of Nonlinear Sciences and Numerical Simulation ; Volume 4, Issue 1 , 2003 , Pages 17-30 ; 15651339 (ISSN) ; Bakhshiani, A ; Mofid, M ; Sharif University of Technology
2003
Abstract
In this paper, an endochronic plasticity model is developed based on a large strain plasticity to describe the behavior of powder material in cold compaction process. The elastic response is stated in terms of hypoelastic model and endochronic plasticity constitutive equations are stated in unrotated frame of reference. A trivially incrementally objective integration scheme for rate constitutive equations is established. Algorithmic modulus consistent with numerical integration algorithm of constitutive equations is extracted. Finally, the numerical schemes are examined for efficacy in the modeling of a plain bush and a rotational-flanged powder compaction component. It is shown how the...
Modelling of powder compaction process using an endochronic plasticity model
, Article Journal of Materials Processing Technology ; Volume 130-131 , 2002 , Pages 175-180 ; 09240136 (ISSN) ; Mofid, M ; Bakhshiani, A ; Sharif University of Technology
2002
Abstract
In this paper, a density-dependent endochronic plasticity is presented for modelling the isothermal deformation behaviour of metal powder at low homologous temperature. As large deformation is observed in powder compaction process, a hypoelastic-plastic formulation is developed in the context of finite deformation plasticity. Constitutive equations are stated in unrotated frame of reference that greatly simplifies endochronic constitutive relation for finite plasticity. The material parameters in the constitutive model are calibrated for a tip shape component by fitting the model to reproduce data from true triaxial compression experiments. Numerical algorithm for accurate and stable...
An integrated software environment for finite element simulation of powder compaction processes
, Article Journal of Materials Processing Technology ; Volume 130-131 , 2002 , Pages 168-174 ; 09240136 (ISSN) ; Sharif University of Technology
2002
Abstract
In this paper, an integrated software environment is demonstrated for computational simulation of powder forming processes. The powder compaction software, PCS_SUT, is designed in both popularity and functionality with the development of user-friendly pre- and post-processing software. Pre-processing software is used to create the model, generate an appropriate finite element grid, apply the appropriate boundary conditions, and view the total model. Post-processing provides visualization of the computed results. In PCS_SUT, a numerical model is developed based on a Lagrangian finite element formulation for large deformations, a cap plasticity theory for non-linear behaviour of material, and...
PCS_SUT: A finite element software for simulation of powder forming processes
, Article Journal of Materials Processing Technology ; Volume 125-126 , 2002 , Pages 602-607 ; 09240136 (ISSN) ; Sharif University of Technology
2002
Abstract
As product complexity increases and economic constraints result in a demand for greater efficiency, industry must invest in new innovative ways to assist design and manufacture. As a first step in the long-term development of such a system, a computer software environment has been developed for pre- and post-processing for unstructured grid-based computational simulation. This paper describes the powder compaction software (PCS_SUT), which is designed for pre- and post-processing for computational simulation of the compaction of powder. Pre-processing software is used to create the model, generate an appropriate finite element grid, apply the appropriate boundary conditions, and view the...
Numerical simulation of powder compaction processes using an inelastic finite element analysis
, Article Materials and Design ; Volume 23, Issue 6 , 2002 , Pages 523-529 ; 02641275 (ISSN) ; Sharif University of Technology
Elsevier Ltd
2002
Abstract
In this paper, a combined experimental and numerical investigation is described for powder compaction processes. It utilises material properties derived from experimental work as input for inelastic analysis of a finite element model. Numerical modelling of the powder compaction process is performed using a large-displacement finite element method. Powder material parameters, such as cohesion, internal friction angle and Young's modulus, were experimentally established as functions of relative density. These non-linear functions are incorporated into the inelastic analysis of the finite element model in order to establish model input parameters during different stages of compaction. Finally,...
3D computational modeling of powder compaction processes using a three-invariant hardening cap plasticity model
, Article Finite Elements in Analysis and Design ; Volume 42, Issue 8-9 , 2006 , Pages 792-807 ; 0168874X (ISSN) ; Khoei, A. R ; Sharif University of Technology
2006
Abstract
In this paper, a three-invariant cap plasticity is developed for description of powder behavior under cold compaction process. The constitutive elasto-plastic matrix and its components are derived as the nonlinear functions of powder relative density. Different aspects of 2D and 3D cap plasticity models are illustrated and the procedure for determination of powder parameters is described. It is shown how the proposed model could generate the elliptical yield surface, double-surface cap plasticity and the irregular hexagonal pyramid of the Mohr-Coulomb and cone-cap yield surface, as special cases. The single-cap plasticity is performed within the framework of large finite element deformation,...
Behavior of dry and saturated soils under impact load during dynamic compaction
, Article 16th International Conference on Soil Mechanics and Geotechnical Engineering: Geotechnology in Harmony with the Global Environment, ICSMGE 2005, Osaka, 12 September 2005 through 16 September 2005 ; Volume 3 , 2005 , Pages 1245-1248 ; 9059660285 (ISBN); 9789059660281 (ISBN) ; Shahir, H ; Ghassemi, A ; Sharif University of Technology
2005
Abstract
Dynamic compaction is a widely used soil improvement method in dry and/or saturated soils. Despite its vast application, its design basis is still empirical and the mechanisms that are involved in the procedure are not fully understood. A fully coupled dynamic finite element code has been developed in order to clarify the ambiguities in the process and predict the strain/displacement field in the ground, determine depth and degree of improvement, and also calculate the pore pressure variation during the process. This model can be used as a rational design tool for dynamic compaction projects
3D dynamic modeling of large plastic deformations in powder die-pressing
, Article Proceedings of the 10th International Conference on Technology of Plasticity, ICTP 2011, 25 September 2011 through 30 September 2011, Aachen ; September , 2011 , Pages 1010-1015 ; 9783514007840 (ISBN) ; Biabanaki, S. O. R ; Parvaneh, S. M ; Sharif University of Technology
2011
Abstract
In this paper, a computational algorithm is presented in three-dimensional dynamic modeling of powder compaction processes. The contact node-to-surface algorithm is employed to impose the contact constraints in large deformation frictional contact, and the contact frictional slip is modified by the Coulomb friction law to simulate the frictional behavior between the rigid punch and the work-piece. The 3D nonlinear contact friction algorithm is employed together with a double-surface cap plasticity model within the framework of large FE deformation in order to predict the non-uniform relative density distribution during the dynamic simulation of powder die-pressing. Finally, the performance...