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Your search keyword '"Nezamabadi, Saeid"' showing total 5 results
Start Over Author "Nezamabadi, Saeid" Topic deformations (mechanics)
5 results on '"Nezamabadi, Saeid"'

1. Compaction of granular materials composed of deformable particles.

Author

Thanh Hai Nguyen, Nezamabadi, Saeid, Delenne, Jean-Yves, and Radjai, Farhang

Subjects
*GRANULAR materials, *COMPACTING, *DEFORMATIONS (Mechanics), *MECHANICAL behavior of materials, *MATERIAL point method
Abstract

In soft particle materials such as metallic powders the particles can undergo large deformations without rupture. The large elastic or plastic deformations of the particles are expected to strongly affect the mechanical properties of these materials compared to hard particle materials more often considered in research on granular materials. Herein, two numerical approaches are proposed for the simulation of soft granular systems: (i) an implicit formulation of the Material Point Method (MPM) combined with the Contact Dynamics (CD) method to deal with contact interactions, and (i) Bonded Particle Model (BPM), in which each deformable particle is modeled as an aggregate of rigid primary particles using the CD method. These two approaches allow us to simulate the compaction of an assembly of elastic or plastic particles. By analyzing the uniaxial compaction of 2D soft particle packings, we investigate the effects of particle shape change on the stress-strain relationship and volume change behavior as well as the evolution of the microstructure. [ABSTRACT FROM AUTHOR]

Published
2017
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2. Analysis of dense packing of highly deformed grains.

Author

Thi Lo Vu, Nezamabadi, Saeid, Barés, Jonathan, and Mora, Serge

Subjects
*GRANULAR materials, *PACKING (Mechanical engineering), *DEFORMATIONS (Mechanics), *STRAINS & stresses (Mechanics), *FRICTION, *COMPRESSION loads
Abstract

This paper concerns modeling of soft granular materials in which the grains are highly deformable. In order to simulate these materials, an approach based on an implicit formulation of the Material Point Method in the context of the finite strain theory, allowing for large deformations of grains, coupled with the Contact Dynamics method for the treatment of unilateral frictional contacts between grains, is proposed. In this context, the Mooney-Rivlin constitutive relationship is applied with two different set of elastic parameters. Considering these two material behaviors, a uniaxial compression of 2D soft granular packings is analyzed. The stress-strain relation and the evolution of the packing fraction as well as of the connectivity of the grains are discussed. [ABSTRACT FROM AUTHOR]

Published
2017
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3. Parallel implicit contact algorithm for soft particle systems.

Author

Nezamabadi, Saeid, Frank, Xavier, Delenne, Jean-Yves, Averseng, Julien, and Radjai, Farhang

Subjects
*PARALLEL algorithms, *DEFORMATIONS (Mechanics), *MESSAGE passing (Computer science), *STRAINS & stresses (Mechanics), *COMPRESSIBILITY, *GRANULAR materials
Abstract

Abstract This paper presents a numerical technique to model soft particle materials in which the particles can undergo large deformations. It combines an implicit finite strain formalism of the Material Point Method and the Contact Dynamics method. In this framework, the large deformations of individual particles as well as their collective interactions are treated consistently. In order to reduce the computational cost, this method is parallelised using the Message Passing Interface (MPI) strategy. Using this approach, we investigate the uniaxial compaction of 2D packings composed of particles governed by a Neo-Hookean material behaviour. We consider compressibility rates ranging from fully compressible to incompressible particles. The packing deformation mechanism is a combination of both particle rearrangements and large deformations, and leads to high packing fractions beyond the jamming state. We show that the packing strength declines when the particle compressibility decreases, and the packing can deform considerably. We also discuss the evolution of the connectivity of the particles and particle deformation distributions in the packing. [ABSTRACT FROM AUTHOR]

Published
2019
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4. MPM with Frictional Contact for Application to Soft Particulate Materials.

Author

Nezamabadi, Saeid, Nguyen, Thanh H., Delenne, Jean-Yves, Averseng, Julien, Frank, Xavier, and Radjai, Farhang

Subjects
MATERIAL point method, FRICTION, DEFORMATIONS (Mechanics), POWDERS, AXIAL loads, ANISOTROPY
Abstract

Soft particle materials are composed of discrete particles that can undergo large deformations without rupture. Most food products, many powders, colloidal pastes, vesicles and biological cells are soft particle systems. In order to model such materials, we present an efficient numerical approach combining an implicit formulation of the Material Point Method (MPM) and Contact Dynamics (CD) method. The MPM deals with bulk variables of an individual particle by discretizing it as a collection of material points, whereas the CD allows for the treatment of frictional contacts between particles. This model is applied for the simulation of the uniaxial compression of 2D soft-particle packings. The compaction is a nonlinear process in which new contacts are formed between particles and the contact areas increase. The change of particle shapes allows these materials to reach high packing fraction. We find that the contact specific surface, the orientation anisotropy and the aspect ratio of particles increase as a function of the packing fraction but at different rates. We also evidence the effect of friction, which favors strong stress chains and thus the elongation of particles, leading to larger values of the orientation anisotropy and the aspect ratio at a given level of packing fraction as compared to a frictionless particle packing. [ABSTRACT FROM AUTHOR]

Published
2017
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5. Implicit frictional-contact model for soft particle systems.

Author

Nezamabadi, Saeid, Radjai, Farhang, Averseng, Julien, and Delenne, Jean-Yves

Subjects
*COMPUTER simulation, *MATERIAL point method, *DEFORMATIONS (Mechanics), *FRICTION, *MATHEMATICAL regularization, *DAMPING (Mechanics)
Abstract

We introduce a novel numerical approach for the simulation of soft particles interacting via frictional contacts. This approach is based on an implicit formulation of the Material Point Method, allowing for large particle deformations, combined with the Contact Dynamics method for the treatment of unilateral frictional contacts between particles. This approach is both precise due to the treatment of contacts with no regularization and artificial damping parameters, and robust due to implicit time integration of both bulk degrees of freedom and relative contact velocities at the nodes representing the contact points. By construction, our algorithm is capable of handling arbitrary particle shapes and deformations. We illustrate this approach by two simple 2D examples: a Hertz contact and a rolling particle on an inclined plane. We also investigate the compaction of a packing of circular particles up to a solid fraction well above the jamming limit of hard particles. We find that, for the same level of deformation, the solid fraction in a packing of frictional particles is above that of a packing of frictionless particles as a result of larger particle shape change. [ABSTRACT FROM AUTHOR]

Published
2015
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