Contact force measurements and stress-induced anisotropy in granular materials

Nature ◽  
2005 ◽  
Vol 435 (7045) ◽  
pp. 1079-1082 ◽  
Author(s):  
T. S. Majmudar ◽  
R. P. Behringer
Keyword(s):  
Granular Materials ◽  
Contact Force ◽  
Force Measurements ◽  
Induced Anisotropy ◽  
Stress Induced Anisotropy

scholarly journals Investigating the Combined Effects of Inherent and Stress-Induced Anisotropy on the Mechanical Behavior of Granular Materials Using Three-Dimensional Discrete Element Method

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Xinran Chen ◽  
Jinsong Qian ◽  
Lei Zhang ◽  
Jianming Ling
Keyword(s):  
Discrete Element Method ◽  
Mechanical Behavior ◽  
Granular Materials ◽  
Three Dimensional ◽  
Discrete Element ◽  
Contact Forces ◽  
Combined Effects ◽  
Induced Anisotropy ◽  
Stress Induced Anisotropy ◽  
Element Method

The three-dimensional discrete element method (DEM) was employed to investigate the combined effects of inherent and stress-induced anisotropy of granular materials. The particles were modeled following real particle shapes. Both isotropic and inherently anisotropic specimens were prepared, and then true triaxial numerical tests were conducted using different intermediate principle stress ratios (b). The results indicate that the oriented particles in the anisotropic specimens form strong contacts in their long axis direction in the early stages of shearing, which restrains the contraction of the specimens. As the strain increases, the oriented particles start to rotate and slide, which results in shorter contraction stages and fewer number of interparticle contacts with peak values compared to the isotropic specimens. In addition, the increase in b values aggravates the rotating and sliding of particles in the inherently anisotropic specimens and restrains the contraction of the granular and the increase of contact forces. As a result, the inherent anisotropy reduces the effects of stress-induced anisotropy on the mechanical behavior of granular materials.

scholarly journals Stress-induced anisotropy in granular materials: fabric, stiffness, and permeability

2015 ◽  
Vol 10 (4) ◽  
pp. 399-419 ◽  
Author(s):  
Matthew R. Kuhn ◽  
WaiChing Sun ◽  
Qi Wang
Keyword(s):  
Granular Materials ◽  
Induced Anisotropy ◽  
Stress Induced Anisotropy

scholarly journals Estimating Contact Force Chains Using Artificial Neural Network

2021 ◽  
Vol 11 (14) ◽  
pp. 6278
Author(s):  
Mengmeng Wu ◽  
Jianfeng Wang
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Particle Size ◽  
Granular Materials ◽  
Coordination Number ◽  
Contact Force ◽  
Force Chains ◽  
Granular System ◽  
Biaxial Test ◽  
Artificial Neural

The inhomogeneous distribution of contact force chains (CFC) in quasi-statically sheared granular materials dominates their bulk mechanical properties. Although previous micromechanical investigations have gained significant insights into the statistical and spatial distribution of CFC, they still lack the capacity to quantitatively estimate CFC evolution in a sheared granular system. In this paper, an artificial neural network (ANN) based on discrete element method (DEM) simulation data is developed and applied to predict the anisotropy of CFC in an assembly of spherical grains undergoing a biaxial test. Five particle-scale features including particle size, coordination number, x- and y-velocity (i.e., x and y-components of the particle velocity), and spin, which all contain predictive information about the CFC, are used to establish the ANN. The results of the model prediction show that the combined features of particle size and coordination number have a dominating influence on the CFC’s estimation. An excellent model performance manifested in a close match between the rose diagrams of the CFC from the ANN predictions and DEM simulations is obtained with a mean accuracy of about 0.85. This study has shown that machine learning is a promising tool for studying the complex mechanical behaviors of granular materials.

scholarly journals A hyperelastic model for soils with stress-induced and inherent anisotropy

2021 ◽  
Author(s):  
Marcin Cudny ◽  
Katarzyna Staszewska
Keyword(s):  
Small Strain ◽  
Induced Anisotropy ◽  
Dynamic Simulations ◽  
Inherent Anisotropy ◽  
Directional Model ◽  
Model Response ◽  
Hyperelastic Model ◽  
Stress Induced Anisotropy ◽  
Stress Invariant ◽  
Independent Model

AbstractIn this paper, modelling of the superposition of stress-induced and inherent anisotropy of soil small strain stiffness is presented in the framework of hyperelasticity. A simple hyperelastic model, capable of reproducing variable stress-induced anisotropy of stiffness, is extended by replacement of the stress invariant with mixed stress–microstructure invariant to introduce constant inherent cross-anisotropic component. A convenient feature of the new model is low number of material constants directly related to the parameters commonly used in the literature. The proposed description can be incorporated as a small strain elastic core in the development of some more sophisticated hyperelastic-plastic models of overconsolidated soils. It can also be used as an independent model in analyses involving small strain problems, such as dynamic simulations of the elastic wave propagation. Various options and features of the proposed anisotropic hyperelastic model are investigated. The directional model response is compared with experimental data available in the literature.

The Magnetic Anisotropy of Co-Base Amorphous Alloys

1991 ◽  
Vol 232 ◽  
Author(s):  
Wu-Xin Zhang ◽  
Xi-Ming Li ◽  
Nan-Ping Chen
Keyword(s):  
Magnetic Anisotropy ◽  
Amorphous Alloys ◽  
Induced Anisotropy ◽  
Pair Model ◽  
Mn Content ◽  
Stress Induced Anisotropy

ABSTRACT4 Co–base amorphous alloys prepared by rapid quenchling are stress–annealed under different temperature (Ta) balow its crytalline temperature Tcry, after pre–annealing. The effect of magnetic anisotropy with Ta shows the mechanism of stress–induced anisotropy is changed from single ionic modal to pair model as Ta inereases. The effect of Mn content may exaggerate the model changing.

Anisotropy Energies and Critical Behavior of Ultrathin Ni(111) Films Grown on Smooth and Rough W(110) (invited)

1991 ◽  
Vol 231 ◽  
Author(s):  
Yi Li ◽  
K. Baberschke
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Film Thickness ◽  
Critical Exponent ◽  
Critical Behavior ◽  
Induced Anisotropy ◽  
Effective Anisotropy ◽  
Stress Induced Anisotropy ◽  
Surface Crystal

Abstract6 to 80 Å thin Ni(111) films were prepared on smooth and rough W(110) substrates in UHV and characterized by LEED and Auger spectroscopies. The measurements of the magnetic properties were carried out in situ by ferromagnetic resonance at 9 GHz between 300 and 600 K. We found that the effective anisotropies, which consist of surface, crystal, and stress induced anisotropy, increase with decreasing film thickness and temperature. The roughness of the substrate results in the drastic decrease of the effective anisotropy. This is attributed to the change of the surface structure and the stress within the Ni films. Furthermore we found that the Curie temperature Tc and the critical exponent β of Ni films on the smooth and rough substrates show no change.

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