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Tác giả hoặc Nhóm tác giả: Thanh Hai NGUYEN, Saeid NEZAMABADI, Farhang RADJAI
Nơi đăng: IV International Conference on Particle-Based Methods. Particles 2015. Spain; Số: ISBN: 978-84-944244-7-2;Từ->đến trang: ;Năm: 2015
Lĩnh vực: Kỹ thuật; Loại: Báo cáo; Thể loại: Quốc tế
Soft-particle materials include colloidal pastes, vesicles, many powders, microgels and suspensions, indicating their diversity and technological importance. These materials share the common feature of being composed of well-defined particles that can undergo large deformations without rupture. In this respect, they differ from hard-particle materials with their plastic behavior mainly governed by particle rearrangements and frictional sliding. Soft particles can reach high packing fractions by particle shape change and still flow plastically. The compaction, volume change behavior under shearing and the properties of the resulting complex textures in soft packing above (the random close packing state) have basically remained unexplored due to the lack of proper numerical and experimental tools. The Discrete Element Methods (DEM) are widely used for modeling particle assemblies due to its ability to take into accounting different loading conditions, particle size distributions and physical properties of the particles. However, the DEM is not suitable for simulating realistic behavior at the sub-particle scale, including large deformations. To model the mechanical properties of soft particles and their mutual interactions, a new methodology is proposed on an implicit formalism of Material Point Method (MPM) coupled with the Contact Dynamics (CD) [1]. In MPM, each particle is discretized by a collection of material points. The information carried by the material points is projected onto a background mesh, where equations of motion are solved. The mesh solution is then used to update the material points. The implicit formulation allows for unconditional numerical stability and efficient coupling with implicit modeling of unilateral contacts and friction between the particles. This implicit MPM-CD model is implemented in a manner that the contact variables (velocity, force...) can be computed simultaneously with bulk variables. This technique MPM is compared with a simpler model in which deformable grains represent an assembly of primary particles interacted by attractive forces and simulated by the CD method. We present an investigation of the compaction process of 2D soft-particle assemblies by means of these proposed models. REFERENCES [1] F. Radjai and V. Richefeu, “Contact dynamics as a nonsmooth discrete element method”, Mechanics of Materials, 41, 715 (2009). [2] M. van Hecke, “Jamming of soft particles: geometry, mechanics, scaling and isostaticity”. J. Phys., 22: 033101, 2010. [3] F. Radjai and F. Dubois, “Discrete numerical modelling of granular materials”, Wiley, Berlin, 2011. [4] S. Nezamabadi, F. Radjai, J. Averseng, J.-Y. Delenne, “Implicit frictional-contact model for soft particle systems”, J. Mech. Phys. Solids, accepted.
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