scholarly journals DEM investigation on strain localization in a dense periodic granular assembly with high coordination number

2021 ◽  
Vol 16 (59) ◽  
pp. 188-197
Author(s):  
Trung-Kien Nguyen ◽  
Thanh-Trung Vo ◽  
Nhu-Hoang Nguyen
Keyword(s):  
Boundary Conditions ◽  
Coordination Number ◽  
Strain Localization ◽  
Biaxial Loading ◽  
Shear Zones ◽  
Discrete Element Modeling ◽  
Perfect Agreement ◽  
Granular Assembly ◽  
High Coordination Number ◽  
High Coordination

Strain localization is one of key phenomena which have been studied extensively in geomaterials and for different kinds of materials including metals and polymers. This well-known phenomenon appears when structure/material is closed to failure. Theoretical, experimental, and numerical research have been dedicated to this subject for a long while. In the numerical aspects, strain localization inside the periodic granular assembly has not been well studied in the literature. In this paper, we investigate the occurrence and development of strain localization within a dense cohesive-frictional granular assembly with high coordination number under bi-periodic boundary conditions by Discrete Element Modeling (DEM). The granular assembly is composed of 2D circular disks and subjected to biaxial loading with constant lateral pressure. The results show that the formation of shear bands is of periodic type, consistent with the boundary conditions. This formation has the origins of the irreversible losing of cohesive contacts, viewed as micro-crackings which strongly concentrated in the periodic shear zones. This micromechanical feature is therefore strongly related to the strain localization observed at the sample scale. Finally, we also show that the strain localization is in perfect agreement with the sample’s displacement fluctuation fields.

scholarly journals Looking beyond kinematics: 3D thermo-mechanical modelling reveals the dynamic of transform margins

2021 ◽  
Author(s):  
Anthony Jourdon ◽  
Charlie Kergaravat ◽  
Guillaume Duclaux ◽  
Caroline Huguen
Keyword(s):  
Boundary Conditions ◽  
Strain Localization ◽  
Numerical Models ◽  
Local Stress ◽  
Shear Zones ◽  
Strike Slip ◽  
Convergent Margins ◽  
Mechanical Modelling ◽  
Kinematic Models ◽  
Extension Direction

Abstract. Transform margins represent ~30 % of the non-convergent margins worldwide. Their formation and evolution have long been addressed through kinematic models that do not account for the mechanical behaviour of the lithosphere. In this study, we use high resolution 3D numerical thermo-mechanical modelling to simulate and investigate the evolution of the intra-continental strain localization under oblique extension. The obliquity is set through velocity boundary conditions that range from 15° (high obliquity) to 75° (low obliquity) every 15° for strong and weak lower continental crust rheologies. Numerical models show that the formation of localized strike-slip shear zones leading to transform continental margins always follows a thinning phase during which the lithosphere is thermally and mechanically weakened. For low (75°) to intermediate (45°) obliquity cases, the strike-slip faults are not parallel to the extension direction but form an angle of 20° to 40° with the plates' motion while for higher obliquities (30° to 15°) the strike-slip faults develop parallel to the extension direction. Numerical models also show that during the thinning of the lithosphere, the stress and strain re-orient while boundary conditions are kept constant. This evolution, due to the weakening of the lithosphere, leads to a strain localization process in three major phases: (1) strain initiates in a rigid plate where structures are sub-perpendicular to the extension direction; (2) distributed deformation with local stress field variations and formation of transtensional and strike-slip structures; (3) formation of highly localized plates boundaries stopping the intra-continental deformation. Our results call for a thorough re-evaluation of the kinematic approach to studying transform margins.

Structure and stereochemistry in 'f-block' complexes of high coordination number. VII. The [M(unidentate X)2(unidentate Y)6] system: Crystal structure of hexaaquadichloroeuropium(III) chloride (a redetermination)

1983 ◽  
Vol 36 (3) ◽  
pp. 477 ◽  
Author(s):  
DL Kepert ◽  
JM Patrick ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Coordination Number ◽  
Title Compound ◽  
Chlorine Atoms ◽  
Coordination Environment ◽  
Twofold Axis ◽  
High Coordination Number ◽  
Europium Atom ◽  
High Coordination

The crystal structure of the title compound [EuCl2(OH2)2]Cl ('europium trichloride hexahydrate') has been redetermined from single-crystal diffractometer data at 295 K and refined to a residual of 0.040 for 1094 independent 'observed' reflections. Crystals are monoclinic, P2/n, a 9.659(3), b 6.529(2), c 7.936(4) �, β 93.67(4)�, Z 2. The europium atom lies on a crystallographic twofold axis, which passes between the two planes of a square-antiprismatic coordination environment in which the two chlorine atoms, on opposite faces, lie cis to each other. Eu-O distances range from 2.401(6) to 2.431(5) �; Eu-Cl is 2.774(2) �.

scholarly journals Organized Plasmonic Clusters with High Coordination Number and Extraordinary Enhancement in Surface-Enhanced Raman Scattering (SERS)

2012 ◽  
Vol 124 (51) ◽  
pp. 12860-12865 ◽  
Author(s):  
Nicolas Pazos-Perez ◽  
Claudia Simone Wagner ◽  
Jose M. Romo-Herrera ◽  
Luis M. Liz-Marzán ◽  
F Javier García de Abajo ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Coordination Number ◽  
Surface Enhanced Raman Scattering ◽  
High Coordination Number ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
High Coordination

scholarly journals New theoretical insight into high coordination number complexes in actinides-centered borane

2020 ◽  
Author(s):  
Shuxian Hu ◽  
Peng Zhang ◽  
wenli zou ◽  
ping zhang
Keyword(s):  
Coordination Number ◽  
Relativistic Quantum ◽  
Structural Motif ◽  
Strong Interactions ◽  
Valuable Insight ◽  
Cage Structure ◽  
Boron Clusters ◽  
Geometric Difference ◽  
High Coordination Number ◽  
High Coordination

<p>The coordination number of a given element behaving to understand its chemistry shows a great interest, which greatly promotes the extension and development of new materials, but remains challenging. Herein we report a new record high coordination number (CN) for actinide established in the cage-like An(BH)<sub>24</sub> (An = Th to Cm) via using relativistic quantum chemistry methods. Analysis of U(BH)<sub>n</sub> (n = 1 to 24) confirms these series of systems being as geometric minima, with the BH as a ligand located in the first shell around the uranium. Contrast, global searches reveal the low CN half-cage structure for UB<sub>24</sub>, which is extended to the series of AnB<sub>24</sub> and prevails over the competing structural isomers such as cage. The intrinsic geometric difference for AnB<sub>24 </sub>and An(BH)<sub>24</sub> mainly arise from the B sp<sup>3</sup> hybridization in borane inducing strong interactions between An 5f6d7s hybrid orbitals and B 2p<sub>z</sub> orbitals in An(BH)<sub>24</sub> comparing to that of AnB<sub>24</sub>. The fundamental trend presents a valuable insight for future experimental endeavor searching for isolable complexes with high-coordination actinide and provides a new structural motif of boron clusters and nanostructures.<br></p>

Theoretical probing of twenty-coordinate actinide-centered boron molecular drums

2021 ◽  
Author(s):  
Juan Wang ◽  
Nai-Xin Zhang ◽  
Congzhi Wang ◽  
Qunyan Wu ◽  
Jianhui Lan ◽  
...  
Keyword(s):  
Coordination Number ◽  
Boron Clusters ◽  
High Coordination Number ◽  
Metal Doped ◽  
High Coordination

The exploration of metal-doped boron clusters has a great significance to design high coordination number (CN) compounds. Actinide-dopted boron clusters are probably candidates for achieving high CNs. In this work,...

scholarly journals New theoretical insights into high-coordination-number complexes in actinides-centered borane

Nanoscale ◽  
2020 ◽  
Vol 12 (28) ◽  
pp. 15054-15065 ◽  
Author(s):  
Shu-Xian Hu ◽  
Peng Zhang ◽  
Wenli Zou ◽  
Ping Zhang
Keyword(s):  
Coordination Number ◽  
New Materials ◽  
High Coordination Number ◽  
High Coordination

The coordination number of a given element affects its behavior, and consequently, there is great interest in understanding the related chemistry, which could greatly promote the extension and development of new materials, but remains challenging.

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