Renewal of basic laws and principles for polar continuum theories (I) —Micropolar continua

2003 ◽  
Vol 24 (10) ◽  
pp. 1119-1125 ◽  
Author(s):  
Dai Tian-min
Keyword(s):  
Micropolar Continua ◽  
Continuum Theories

scholarly journals Applications of micropolar SPH in geomechanics

2021 ◽  
Author(s):  
Chengwei Zhu ◽  
Chong Peng ◽  
Wei Wu
Keyword(s):  
Strain Localization ◽  
Biaxial Compression ◽  
Parameter Study ◽  
Sand Column ◽  
Column Collapse ◽  
Micropolar Continua ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Micropolar Model ◽  
Geotechnical Problems

AbstractA smoothed particle hydrodynamics code based on micropolar continua for geomaterials is developed for problems involving large deformation and shear strain localization. Two typical geotechnical problems, i.e., biaxial compression test and sand column collapse, are simulated using classical and micropolar model to demonstrate the performance of the newly proposed method. A parameter study is given on the scale effect in the micropolar continua.

scholarly journals Comparative 3D DEM simulations of sand–structure interfaces with similarly shaped clumps versus spheres with contact moments

2021 ◽  
Author(s):  
A. Grabowski ◽  
M. Nitka ◽  
J. Tejchman
Keyword(s):  
Particle Shape ◽  
Friction Angle ◽  
Rigid Wall ◽  
Numerical Results ◽  
Contact Forces ◽  
Interface Roughness ◽  
Interface Shear ◽  
Dem Simulations ◽  
Micropolar Continua ◽  
Interface Behaviour

AbstractThree-dimensional simulations of a monotonic quasi-static interface behaviour between initially dense cohesionless sand and a rigid wall of different roughness during tests in a parallelly guided direct shear test under constant normal stress are presented. Numerical modelling was carried out by the discrete element method (DEM) using clumps in the form of convex non-symmetric irregularly shaped grains. The clumps had an aspect ratio of 1.5. A regular grid of triangular grooves (asperities) along the wall with a different height at the same distance was assumed. The numerical results with clumps were directly compared under the same conditions with our earlier DEM simulations using pure spheres with contact moments with respect to the peak and residual interface friction angle, width of the interface shear zone, ratio between grain slips and grain rotations, distribution of contact forces and stresses. The difference between the behaviour of clumps and pure spheres with contact moments proved to be noticeable in the post-peak regime due to a different particle shape. The rolling resistance model with pure spheres was proved to be limited for capturing particle shape effects. Three different boundary conditions along the interface were proposed for micropolar continua, considering grain rotations and grain slips, wall grain moments and wall grain forces, and normalized interface roughness. The numerical results in this paper offer a better understanding of the interface behaviour of granular bodies in DEM and FEM simulations.

scholarly journals SHEARING TESTS APPLIED TO PANTOGRAPHIC STRUCTURES

2016 ◽  
Vol 7 ◽  
pp. 1 ◽  
Author(s):  
Gregor Ganzosch ◽  
Francesco Dell’Isola ◽  
Emilio Turco ◽  
Tomasz Lekszycki ◽  
Wolfgang H. Müller
Keyword(s):  
Rapid Manufacturing ◽  
Pantographic Structures ◽  
Deformation Response ◽  
Shear Loads ◽  
Generalized Continuum ◽  
Complete Failure ◽  
Elastic Cylinders ◽  
Inextensible Fibers ◽  
Fabric Materials ◽  
Continuum Theories

With the advancements in 3D printing technology, rapid manufacturing of fabric materials with complex geometries became possible. By exploiting this technique, different materials with different structures have been developed in the recent past with the objective of making generalized continuum theories useful for technological applications. So-called pantographic structures are introduced: Inextensible fibers are printed in two arrays orthogonal to each other in parallel planes. These superimposed planes are inter-connected by elastic cylinders. Five differently-sized samples were subjected to shear-like loading while their deformation response was analyzed. Results show that deformation behavior is strong non-linear for all samples. Furthermore, all samples were capable to resist considerable external shear loads without leading to complete failure of the whole structure. This extraordinary behavior makes these structures attractive to serve as an extremely tough metamaterial.

The Atomistic and the Continuum Theories of Crystal Elasticity

1961 ◽  
Vol 463 (3-4) ◽  
pp. 121-136 ◽  
Author(s):  
R. S. Krishnan ◽  
E. S. Rajagopal
Keyword(s):  
Continuum Theories ◽  
The Continuum

A Finite-Temperature Continuum Theory Based on Interatomic Potentials

2005 ◽  
Vol 127 (4) ◽  
pp. 408-416 ◽  
Author(s):  
H. Jiang ◽  
Y. Huang ◽  
K. C. Hwang
Keyword(s):  
Temperature Dependence ◽  
Finite Temperature ◽  
Interatomic Potential ◽  
Coefficient Of Thermal Expansion ◽  
Harmonic Approximation ◽  
Continuum Theory ◽  
Single Wall Carbon Nanotubes ◽  
Interatomic Potentials ◽  
Atomistic Models ◽  
Continuum Theories

There are significant efforts to develop continuum theories based on atomistic models. These atomistic-based continuum theories are limited to zero temperature (T=0K). We have developed a finite-temperature continuum theory based on interatomic potentials. The effect of finite temperature is accounted for via the local harmonic approximation, which relates the entropy to the vibration frequencies of the system, and the latter are determined from the interatomic potential. The focus of this theory is to establish the continuum constitutive model in terms of the interatomic potential and temperature. We have studied the temperature dependence of specific heat and coefficient of thermal expansion of graphene and diamond, and have found good agreements with the experimental data without any parameter fitting. We have also studied the temperature dependence of Young’s modulus and bifurcation strain of single-wall carbon nanotubes.

scholarly journals Chiral skyrmions in the plane

2014 ◽  
Vol 470 (2172) ◽  
pp. 20140394 ◽  
Author(s):  
Christof Melcher
Keyword(s):  
Nuclear Physics ◽  
Topological Charge ◽  
Energy Contribution ◽  
Promising Candidate ◽  
Linear Gradient ◽  
Topological Solitons ◽  
Zeeman Field ◽  
Continuum Theories ◽  
Least Energy ◽  
Moriya Interaction

Magnets without inversion symmetry are a prime example of a solid-state system featuring topological solitons on the nanoscale, and a promising candidate for novel spintronic applications. Magnetic chiral skyrmions are localized vortex-like structures, which are stabilized by antisymmetric exchange interaction, the so-called Dzyaloshinskii–Moriya interaction. In continuum theories, the corresponding energy contribution is, in contrast to the classical Skyrme mechanism from nuclear physics, of linear gradient dependence and breaks the chiral symmetry. In the simplest possible case of a ferromagnetic energy in the plane, including symmetric and antisymmetric exchange and Zeeman interaction, we show that the least energy in a class of fields with unit topological charge is attained provided the Zeeman field is sufficiently large.

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