An endochronic plasticity model for numerical simulation of industrial powder compaction processes

Khoei, A.R.; Bakhshiani, A.; Mofid, Massood

doi:10.1002/cnm.610

Cited by 4 publications

References 25 publications

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Modeling of Powder Forming Processes; Application of a Three‐Invariant Cap Plasticity and an Enriched Arbitrary Lagrangian–Eulerian FE Method

Khoei

2010

Advanced Computational Materials Modeling

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Powder metallurgy is a highly developed method of manufacturing reliable ferrous and nonferrous parts. The powder metallurgy process is cost-effective, because it minimizes machining, produces good surface finish, and maintains close dimensional tolerances. The method is a material-processing technique utilized to achieve a coherent near-to-net shape industrial component. The often extremely high tolerance requirements of the parts and the cost for hard machining of a sintered component are a challenge for die pressing. One of the main difficulties that exists in the compaction-forming process of powders includes a nonhomogeneous density distribution, which has wide ranging effects on the final performance of the compacted part. The variation of density results in cracks and also in localized deformation in the compact, producing regions of high density surrounded by lower density material, leading to compact failure. The lack of homogeneity is primarily caused by friction, due to interparticle movement, as well as relative slip between powder particles and the die wall. The die geometry and the sequence of movement result in a lack of homogeneity of density distribution in a compact. Thus, the success of compaction forming depends on the ability of the process in imparting a uniform density distribution in the engineered part. In order to perform such analysis, the complex mechanisms of compaction process must be drawn into a mathematical formulation with the knowledge of material behavior.A number of constitutive models have been developed for the compaction of powders over the last three decades, including micromechanical models [1-3], flow formulations [4], and solid mechanics models [5][6][7][8][9][10][11]. The porous material model, generally known as a modified von Mises criterion [12], has been used for the simulation of powder-forming processes. This model includes the influence of the hydrostatic stress component, and satisfies the symmetry and convexity conditions required for the development of a plasticity theory. The yielding of porous materials is more complicated than that of fully dense materials, because the onset of yielding is influenced not only by the deviatoric stress components

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Modeling of Powder Forming Processes; Application of a Three‐Invariant Cap Plasticity and an Enriched Arbitrary Lagrangian–Eulerian FE Method

Khoei

2010

Advanced Computational Materials Modeling

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A total Lagrangian framework for simulation of powder compaction process based on a smooth three‐surface Cap model and a mesh‐free method

Rossi

Alves

Al-Qureshi

2008

Numerical Meth Engineering

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SUMMARYThis 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.

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2005

Computational Plasticity in Powder Forming Processes

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An endochronic plasticity model for numerical simulation of industrial powder compaction processes

Cited by 4 publications

References 25 publications

Modeling of Powder Forming Processes; Application of a Three‐Invariant Cap Plasticity and an Enriched Arbitrary Lagrangian–Eulerian FE Method

Modeling of Powder Forming Processes; Application of a Three‐Invariant Cap Plasticity and an Enriched Arbitrary Lagrangian–Eulerian FE Method

A total Lagrangian framework for simulation of powder compaction process based on a smooth three‐surface Cap model and a mesh‐free method

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