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Amir R. Khoei - One of the best experts on this subject based on the ideXlab platform.

  • Genetic algorithm-based numerical optimization of Powder Compaction Process with temperature-dependent cap plasticity model
    The International Journal of Advanced Manufacturing Technology, 2013
    Co-Authors: Sh. Keshavarz, Amir R. Khoei, Z. Molaeinia
    Abstract:

    In this paper, a shape optimization technique is presented for the cold and hot isostatic pressing of metal Powders based on the genetic algorithm (GA) approach. The GA technique is used to obtain the desired optimal compacted component by changing the boundaries of component and verifying the prescribed constraints. The coupled thermomechanical analysis of hot isostatic pressing is employed for metal Powders during densification Process. The numerical modeling of hot Powder Compaction simulation is performed based on the large deformation formulation, temperature-dependent cap plasticity model, and frictional contact algorithm. The modified cap plasticity takes the temperature effects into the numerical simulation of highly nonlinear behavior of metal Powder. Finally, numerical examples are analyzed to demonstrate the feasibility of proposed optimization algorithm for designing Powder components in the cold- and hot-forming Processes of Powder Compaction.

  • Arbitrary Lagrangian–Eulerian method in plasticity of pressure-sensitive material: application to Powder forming Processes
    Computational Mechanics, 2008
    Co-Authors: Amir R. Khoei, M. Anahid, K Shahim, H. Dormohammadi
    Abstract:

    In this paper, an application of Arbitrary Lagrangian–Eulerian (ALE) method is presented in plasticity behavior of pressure-sensitive material, with special reference to large deformation analysis of Powder Compaction Process. In ALE technique, the reference configuration is used for describing the motion, instead of material configuration in Lagrangian, and spatial configuration in Eulerian formulation. The convective term is used to reflect the relative motion between the mesh and the material. Each time-step is divided into the Lagrangian phase and Eulerian phase. The convection term is neglected in the material phase, which is identical to a time-step in a standard Lagrangian analysis. The stresses and plastic internal variables are converted to account the relative mesh-material motion in the convection phase. The ALE formulation is then performed within the framework of a three-invariant cap plasticity model in order to predict the non-uniform density distribution during the large deformation of Powder die pressing. The plasticity model is based on a hardening rule with the isotropic and kinematic material functions. The constitutive elasto-plastic matrix and its components are derived by using the definition of yield surface, material functions and non-linear elastic behavior, as function of hardening parameters. Finally, the numerical examples are performed to illustrate the applicability of the computational algorithm in modeling of Powder forming Process and the results are compared with those obtained from Lagrangian simulation in order to demonstrate the accuracy of proposed model.

  • Contact friction simulation in Powder Compaction Process based on the penalty approach
    Materials & Design, 2008
    Co-Authors: Sh. Keshavarz, Amir R. Khoei, Alireza Khaloo
    Abstract:

    Abstract In this paper, the influence of Powder–tool friction on the mechanical properties of the final product is investigated in pressing metal Powders. A computational algorithm is presented for simulation of frictional contact in the Compaction Process of Powder. The large deformation finite element (FE) formulation is characterized by the use of penalty approach in which a plasticity theory of friction is incorporated to simulate sliding resistance at the Powder–tool interface. The constitutive relations for friction are derived from a Coulomb friction law. A double-surface cap plasticity model is employed together with the nonlinear contact friction behavior in numerical simulation of Powder material. The contact friction algorithm together with the cap plasticity model is incorporated within the framework of large FE deformation in order to predict the non-uniform relative density distribution during large deformation of Powder die pressing. Finally, the numerical schemes are examined for efficiency in modeling of a set of Powder components.

  • Reproducing Kernel Particle Method in Plasticity of Pressure-Sensitive Material with Reference to Powder Forming Process
    Computational Mechanics, 2007
    Co-Authors: Amir R. Khoei, Mansooreh Samimi, A R Azami
    Abstract:

    In this paper, an application of the reproducing kernel particle method (RKPM) is presented in plasticity behavior of pressure-sensitive material. The RKPM technique is implemented in large deformation analysis of Powder Compaction Process. The RKPM shape function and its derivatives are constructed by imposing the consistency conditions. The essential boundary conditions are enforced by the use of the penalty approach. The support of the RKPM shape function covers the same set of particles during Powder Compaction, hence no instability is encountered in the large deformation computation. A double-surface plasticity model is developed in numerical simulation of pressure-sensitive material. The plasticity model includes a failure surface and an elliptical cap, which closes the open space between the failure surface and hydrostatic axis. The moving cap expands in the stress space according to a specified hardening rule. The cap model is presented within the framework of large deformation RKPM analysis in order to predict the non-uniform relative density distribution during Powder die pressing. Numerical computations are performed to demonstrate the applicability of the algorithm in modeling of Powder forming Processes and the results are compared to those obtained from finite element simulation to demonstrate the accuracy of the proposed model.

  • The extended finite element method (X-FEM) for Powder forming problems
    Journal of Materials Processing Technology, 2006
    Co-Authors: Amir R. Khoei, M. Anahid, Amir Shamloo, K Shahim
    Abstract:

    Abstract In this paper, the eXtended Finite Element Method (X-FEM) is developed in pressure-sensitive plasticity of Powder Compaction Process. In X-FEM, the need for mesh adaption to discontinuity interface is neglected and the Process is accomplished by employing additional functions, which are added to approximate the displacement field of the elements located on the interface. The double-surface cap plasticity model is employed within the X-FEM framework in numerical simulation of Powder material. The plasticity model includes a failure surface and an elliptical cap, which closes the open space between the failure surface and hydrostatic axis. The moving cap expands in the stress space according to a specified hardening rule. The application of X-FEM technique in simulation of Powder material is presented in an incremental manner. Finally, the numerical example of a shaped tablet component is analyzed numerically.

A K Ariffin - One of the best experts on this subject based on the ideXlab platform.

  • Numerical simulation and experimentation of warm metal Powder Compaction Process
    Key Engineering Materials, 2011
    Co-Authors: Mujibur Rahman, A K Ariffin, Faris Tarlochan, Ramesh Singh, S.s.m. Nor
    Abstract:

    Powder Compaction at elevated temperature or known as warm Compaction is a Process of producing green compacts from metal Powder, which is generally conducted between the ambient and the recrystalization temperature of the main Powder constituent. Even though, warm Compaction was initiated at around 1998, not a lot of information can be found in the literature especially on the numerical simulation of the Process. Therefore, this paper presents the simulation of warm metal Powder forming Process by using the developed computer code. The Elliptical Cap yield model has been used to represent the deformation behaviour of the Powder mass during the forming Process at above ambient temperature. The material properties of Powder mass, i. e., friction coefficient, elastic index, and plastic index, at different forming temperature, are established through warm Compaction experiment. The simulation was conducted to generate a green compact of a plain bush component. Some numerical simulation results were validated through experimentation, where a good agreement was found between the numerical simulation and the experimental results.

  • Finite element modelling of crack propagation in metal Powder Compaction using Mohr–Coulomb and Elliptical Cap yield criteria
    Powder Technology, 2010
    Co-Authors: S. M. Tahir, A K Ariffin, Mohd Shamsul Anuar
    Abstract:

    In the modelling of the Compaction Process of particulate materials into a coherent green body, an appropriate yield criterion for the deformation Process has to be selected. In this paper, two commonly used yield criteria for Powder Compaction, namely Mohr–Coulomb and Elliptical Cap are utilized in the finite element modelling of iron Powder Compaction Process, which incorporates a fracture criterion of granular materials in compression. The simulated crack growth patterns obtained by using these two yield criteria were compared in terms of the influence of shear stress and relative density distributions. This work has shown that the application of the Elliptical Cap yield model gives a more realistic simulated Mode II crack propagation during the densification stage of the metal Powder Compaction Process in comparison to the Mohr–Coulomb yield model.

  • development of a finite element model of metal Powder Compaction Process at elevated temperature
    Applied Mathematical Modelling, 2009
    Co-Authors: Mujibur Rahman, A K Ariffin
    Abstract:

    This paper presents the finite element modelling of metal Powder Compaction Process at elevated temperature. In the modelling, the behaviour of Powder is assumed to be rate independent thermo-elastoplastic material where the material constitutive laws are derived based on a continuum mechanics approach. The deformation Process of metal Powder has been described by a large displacement based finite element formulation. The Elliptical Cap yield model has been used to represent the deformation behaviour of the Powder mass during the Compaction Process. This yield model was tested and found to be appropriate to represent the Compaction Process. The staggered-incremental-iterative solution strategy has been established to solve the non-linearity in the systems of equations. Some numerical simulation results were validated through experimentation, where a good agreement was found between the numerical simulation results and the experimental data.

  • the effect of lubrication in reducing net friction in warm Powder Compaction Process
    Journal of Materials Processing Technology, 2008
    Co-Authors: Mujibur Rahman, B Shahida, Faris Tarlochan, A K Ariffin
    Abstract:

    Abstract Warm Powder Compaction Process is an advanced type of the conventional cold Compaction Process in producing a green compact, which is conducted at elevated temperature. Metal Powder inside a die is compressed completely after heating the whole system at elevated temperature ranges from 100 °C to 150 °C. During the Compaction Process, friction occurs between the metal Powder, the die surface and between the Powders itself. The entire Compaction phases as well as the density of green compact are eventually affected because of the Process. The aim of this paper is to discuss the effect of lubrication in term of the mixing time, weight percent of lubricant and the density of metal Powder through warm Compaction. The metal Powder that used was in the Process was an iron ASC 100.29. The Compaction experiments have been conducted at 130 °C and the lubricants used was zinc stearate and carbon. It was found that the Compaction phases (Compaction and ejection) are strongly dependant on the variables used.

  • thermal mechanical model of warm Powder Compaction Process
    Journal of Materials Processing Technology, 2001
    Co-Authors: A K Ariffin, Norhamidi Muhamad, Md Mujibur Rahman, Jaafar Sahari
    Abstract:

    Abstract A coupled mechanical and thermal analysis of Powder during the warm Compaction Process has been investigated. This paper presents the development of the numerical model to generate a green compact through uniaxial die Compaction. The Powder is considered to be the rate independent thermo-elastoplastic material. The constitutive laws are derived based on a continuum approach and the governing equations are developed where the thermal strain is taken into account together with elastic and plastic strains. The Elliptical Cap failure criterion is considered to model the yielding of the material during the Process. A large displacement based finite element approach is used considering an updated Lagrangian strategy. The non-linear systems of equations are solved employing the staggered-incremental-iterative solution strategy.

Rodrigo Rossi - One of the best experts on this subject based on the ideXlab platform.

  • a total lagrangian framework for simulation of Powder Compaction Process based on a smooth three surface cap model and a mesh free method
    International Journal for Numerical Methods in Engineering, 2008
    Co-Authors: Rodrigo Rossi, Marcelo Krajnc Alves, Hazim Ali Alqureshi
    Abstract:

    This paper presents a detailed framework for simulation of cold Powder Compaction Process. This framework consists of the following main assumptions: The total Lagrangian description is employed; the Powder is assumed to be isotropic and it is modeled by a complete, smooth three-surface Cap model; the constitutive formulation is based on the multiplicative decomposition of the deformation gradient and on stress–strain pair formed by the Hencky logarithmic strain and the rotated Kirchhoff stress tensor; the elastic constitutive relationship considers that some parameters are dependent upon the relative density of the Powder; the contact formulation is based on the Signorini condition and the friction is modeled by using a regularized Coulomb model; and the spatial discretization is made by the element-free Galerkin method where the essential boundary conditions are enforced via an augmented Lagrangian method. Details concerning the discretization and the linearization of the weak form are presented and a master algorithm is proposed. Some key examples already investigated by other authors, but with somewhat different approaches, are revisited in this paper in order to investigate the adequacy of the proposed model and attest the performance of the proposed numerical scheme. Copyright © 2008 John Wiley & Sons, Ltd.

  • A total Lagrangian framework for simulation of Powder Compaction Process based on a smooth three‐surface Cap model and a mesh‐free method
    International Journal for Numerical Methods in Engineering, 2008
    Co-Authors: Rodrigo Rossi, Marcelo Krajnc Alves, Hazim Ali Al-qureshi
    Abstract:

    This paper presents a detailed framework for simulation of cold Powder Compaction Process. This framework consists of the following main assumptions: The total Lagrangian description is employed; the Powder is assumed to be isotropic and it is modeled by a complete, smooth three-surface Cap model; the constitutive formulation is based on the multiplicative decomposition of the deformation gradient and on stress–strain pair formed by the Hencky logarithmic strain and the rotated Kirchhoff stress tensor; the elastic constitutive relationship considers that some parameters are dependent upon the relative density of the Powder; the contact formulation is based on the Signorini condition and the friction is modeled by using a regularized Coulomb model; and the spatial discretization is made by the element-free Galerkin method where the essential boundary conditions are enforced via an augmented Lagrangian method. Details concerning the discretization and the linearization of the weak form are presented and a master algorithm is proposed. Some key examples already investigated by other authors, but with somewhat different approaches, are revisited in this paper in order to investigate the adequacy of the proposed model and attest the performance of the proposed numerical scheme. Copyright © 2008 John Wiley & Sons, Ltd.

  • A model for the simulation of Powder Compaction Processes
    Journal of Materials Processing Technology, 2007
    Co-Authors: Rodrigo Rossi, Marcelo Krajnc Alves, Hazim Ali Al-qureshi
    Abstract:

    Abstract In this work the simulation of the Powder Compaction Process, in the context of Powder Metallurgy, is numerically investigated. The procedure considers that the Powder is being modeled by a complete smooth three surface Cap model and makes use of a spatial approximation which is performed in the context of the element-free Galerkin (EFG) method. The constitutive model is written in terms of the rotated Kirchhoff stress and of its logarithmic strain conjugate measure. A total Lagrangian description is considered and the imposition of the essential boundary condition is made by the augmented Lagrangian method. The contact formulation used in this work assumes the Signorini condition. In order to apply the EFG method, the body domain is partitioned into a triangular background integration mesh, with the particles positioned at the vertices. Some numerical results are presented, in order to attest the performance of the proposed methodology.

Hazim Ali Al-qureshi - One of the best experts on this subject based on the ideXlab platform.

  • A total Lagrangian framework for simulation of Powder Compaction Process based on a smooth three‐surface Cap model and a mesh‐free method
    International Journal for Numerical Methods in Engineering, 2008
    Co-Authors: Rodrigo Rossi, Marcelo Krajnc Alves, Hazim Ali Al-qureshi
    Abstract:

    This paper presents a detailed framework for simulation of cold Powder Compaction Process. This framework consists of the following main assumptions: The total Lagrangian description is employed; the Powder is assumed to be isotropic and it is modeled by a complete, smooth three-surface Cap model; the constitutive formulation is based on the multiplicative decomposition of the deformation gradient and on stress–strain pair formed by the Hencky logarithmic strain and the rotated Kirchhoff stress tensor; the elastic constitutive relationship considers that some parameters are dependent upon the relative density of the Powder; the contact formulation is based on the Signorini condition and the friction is modeled by using a regularized Coulomb model; and the spatial discretization is made by the element-free Galerkin method where the essential boundary conditions are enforced via an augmented Lagrangian method. Details concerning the discretization and the linearization of the weak form are presented and a master algorithm is proposed. Some key examples already investigated by other authors, but with somewhat different approaches, are revisited in this paper in order to investigate the adequacy of the proposed model and attest the performance of the proposed numerical scheme. Copyright © 2008 John Wiley & Sons, Ltd.

  • A model for the simulation of Powder Compaction Processes
    Journal of Materials Processing Technology, 2007
    Co-Authors: Rodrigo Rossi, Marcelo Krajnc Alves, Hazim Ali Al-qureshi
    Abstract:

    Abstract In this work the simulation of the Powder Compaction Process, in the context of Powder Metallurgy, is numerically investigated. The procedure considers that the Powder is being modeled by a complete smooth three surface Cap model and makes use of a spatial approximation which is performed in the context of the element-free Galerkin (EFG) method. The constitutive model is written in terms of the rotated Kirchhoff stress and of its logarithmic strain conjugate measure. A total Lagrangian description is considered and the imposition of the essential boundary condition is made by the augmented Lagrangian method. The contact formulation used in this work assumes the Signorini condition. In order to apply the EFG method, the body domain is partitioned into a triangular background integration mesh, with the particles positioned at the vertices. Some numerical results are presented, in order to attest the performance of the proposed methodology.

Nobuhiro Yoshikawa - One of the best experts on this subject based on the ideXlab platform.

  • large scale aluminum foam plate fabricated by enhanced friction Powder Compaction Process based on sintering and dissolution Process
    Journal of Materials Processing Technology, 2014
    Co-Authors: Yoshihiko Hangai, Kousuke Zushida, Osamu Kuwazuru, Nobuhiro Yoshikawa
    Abstract:

    Abstract An enhanced friction Powder Compaction (FPC) Process was proposed for fabricating a large plate of aluminum foam by the sintering and dissolution Process. In this Process, the rotating tool plunged into the die filled with a Powder mixture of aluminum and NaCl during the FPC Process was made to traverse perpendicularly to the direction of plunging as in the case of friction stir welding. In the enhanced FPC Process, no external heat source, such as an electric furnace or a spark plasma sintering, was necessary for fabricating aluminum foam, except for the friction heat generated by traversing the rotating tool. It was found that a long plate of aluminum foam can be fabricated with a length equal to the tool traversing length. By X-ray computed tomography (CT) and scanning electron microscopy (SEM) observations of the pore structures of the fabricated aluminum foam, it was found that the entire sample had a pore structures that was similar to the NaCl morphology, regardless of the position along the traversing direction. The fabricated aluminum foam had a similar stress–strain curve to that of aluminum foam fabricated by spark plasma sintering and exhibited ductile fracture. This is considered to be attributed to the good bonding between aluminum particles in the entire sample. The fabricated aluminum foam exhibited almost the same plateau stress regardless of the position along the traversing direction.

  • friction Powder Compaction Process for fabricating open celled cu foam by sintering dissolution Process route using nacl space holder
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013
    Co-Authors: Yoshihiko Hangai, Kousuke Zushida, Hidetoshi Fujii, Rintaro Ueji, Osamu Kuwazuru, Nobuhiro Yoshikawa
    Abstract:

    Abstract Open-celled metal foams have received considerable attention in various fields and are expected to be used as engineering materials where heat exchange, sound absorption and filtration are required. In this study, Cu foam specimens with NaCl volume fractions of 60%, 70% and 80% were successfully fabricated by the friction Powder Compaction (FPC) Process with the sintering and dissolution Process (SDP) using NaCl as space holders. In the FPC Process, no external heat source was used for fabricating Cu foam except for the friction heat generated by the rotating tool plunged into the die and Powders. From the X-ray CT and SEM observation of the pore structures of the fabricated Cu foam, it was found that almost the entire specimen had a pore structure similar to the NaCl morphology, regardless of the NaCl volume fraction. This is mainly because the sintering Process for Cu particles in the FPC Process was achieved at a temperature lower than the melting point of NaCl. From compression tests of the fabricated Cu foam, Cu foam exhibited ductile fracture regardless of its NaCl volume fraction, which is considered to be attributed to the good bonding between Cu particles. The plateau stress and energy absorption decreased with increasing NaCl volume fraction, indicating strong relationships between them. The Cu foam with the highest energy absorption per unit volume up to the specific stress changed from the high-NaCl-volume-fraction Cu foam to the low-NaCl-volume-fraction Cu foam with increasing compression stress. Consequently, it was shown that the mechanical properties of Cu foam can be controlled by adjusting the volume fraction of NaCl.

  • effect of die material on compressive properties of open cell porous aluminum fabricated by friction Powder Compaction Process
    Materials Transactions, 2013
    Co-Authors: Yoshihiko Hangai, Osamu Kuwazuru, Hiroaki Yoshida, Nobuhiro Yoshikawa
    Abstract:

    Porous Al is expected to be used for a variety of applications such as automotive components and building materials owing to its high functionality and light weight.1) Among the numerous fabrication Processes of porous Al, the sintering and dissolution Process (SDP) is a promising route for fabricating open-cell porous Al.2­8) In this Process, a mixture of Al Powder and NaCl Powder is sintered by applying appropriate pressure and heat using an electric furnace2­5) or by spark plasma sintering (SPS).6­8) Then, the sintered mixture is placed in water to remove the NaCl and obtain porous Al. Recently, a new friction Powder Compaction (FPC) Process, which requires no external heat source for Powder sintering, has been developed.9,10) Porous Al can be fabricated by combining the SDP and the FPC Process.9) In this combined Process, the sintering of the Powder mixture is conducted simply by plunging a rotating tool into a die filled with the mixture, and sintering is induced by the friction heat and pressing load generated by the rotating tool plunging into the die. It is considered that the pressing load and temperature during the sintering Process directly affect the degree of sintering of the mixture, namely, the mechanical properties of the obtained porous Al. In friction stir welding (FSW), it is known that the welding temperature and load are significantly different in the FSW of Cu and that of Al.11) In this study, Cu (referred to as FPC-Cu hereinafter) and Al (FPC-Al) dies were used and the effect of the difference in the die material on the mechanical properties of the obtained porous Al was investigated. In addition, the mechanical properties of the obtained porous Al were compared with those of other porous Al samples fabricated by the SDP route, in which the sintering of the mixture is conducted by SPS.6­8)

  • Friction Powder Compaction Process for fabricating porous Cu by space holder route
    Proceedings of the 1st International Joint Symposium on Joining and Welding, 2013
    Co-Authors: Yoshihiko Hangai, Kousuke Zushida, Hidetoshi Fujii, Osamu Kuwazuru, Yufeng Sun, Yoshiaki Morisada, Nobuhiro Yoshikawa
    Abstract:

    Functionally graded (FG) porous copper (Cu) consisting of layers with porosity p = 80% and 60% in a single porous Cu specimen was fabricated by a friction Powder Compaction (FPC) Process via a sintering and dissolution Process route. The FPC Process is very simple and energy efficient since it only requires a rotating tool to be plunged into an oxygen-free Cu plate with a hole filled with a mixture of Cu Powder and NaCl Powder, and no external heat source is necessary. The sintering of the Powder is mainly achieved by the friction heat and pressing load generated by the rotating tool in the oxygen-free Cu plate and Powder. It was shown that the fabricated FG porous Cu has the potential to exhibit two plateau regions with almost the same plateau stresses as uniform porous Cu with p = 80% and 60%.