Numerical study on patterning of shear bands in a Cosserat continuum

1993 ◽  
Vol 99 (1-4) ◽  
pp. 61-74 ◽  
Author(s):  
J. Tejchman ◽  
W. Wu
Keyword(s):  
Numerical Study ◽  
Shear Bands ◽  
Cosserat Continuum

Analysis of shear bands in slow granular flows using a frictional Cosserat model

2000 ◽  
Vol 627 ◽  
Author(s):  
Prabhu R. Nott ◽  
K. Kesava Rao ◽  
L. Srinivasa Mohan
Keyword(s):  
Scaling Laws ◽  
Shear Bands ◽  
Shear Layers ◽  
Theoretical Description ◽  
Field Variable ◽  
Cosserat Continuum ◽  
Momentum Balance ◽  
Rigid Plastic ◽  
Independent Field ◽  
Cosserat Model

ABSTRACTThe slow flow of granular materials is often marked by the existence of narrow shear layers, adjacent to large regions that suffer little or no deformation. This behaviour, in the regime where shear stress is generated primarily by the frictional interactions between grains, has so far eluded theoretical description. In this paper, we present a rigid-plastic frictional Cosserat model that captures thin shear layers by incorporating a microscopic length scale. We treat the granular medium as a Cosserat continuum, which allows the existence of localised couple stresses and, therefore, the possibility of an asymmetric stress tensor. In addition, the local rotation is an independent field variable and is not necessarily equal to the vorticity. The angular momentum balance, which is implicitly satisfied for a classical continuum, must now be solved in conjunction with the linear momentum balances. We extend the critical state model, used in soil plasticity, for a Cosserat continuum and obtain predictions for flow in plane and cylindrical Couette devices. The velocity profile predicted by our model is in qualitative agreement with available experimental data. In addition, our model can predict scaling laws for the shear layer thickness as a function of the Couette gap, which must be verified in future experiments. Most significantly, our model can determine the velocity field in viscometric flows, which classical plasticity-based model cannot.

Dynamic Patterning of Shear Bands in Cosserat Continuum

1997 ◽  
Vol 123 (2) ◽  
pp. 123-133 ◽  
Author(s):  
J. Tejchman ◽  
W. Wu
Keyword(s):  
Shear Bands ◽  
Cosserat Continuum

scholarly journals Notch Effect on Plastic Deformation of Metallic Glass: A Numerical Study by Revised Free-Volume Theory

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
J. F. Yan ◽  
W. J. Meng ◽  
Z. Chen ◽  
H. Guo ◽  
X. G. Yan
Keyword(s):  
Metallic Glass ◽  
Free Volume ◽  
Numerical Study ◽  
Shear Bands ◽  
Notch Effect ◽  
Volume Distribution ◽  
Free Volume Theory ◽  
Tension And Compression ◽  
Strength Asymmetry ◽  
Strength And Plasticity

By means of a revised free-volume theory, the notch effect on metallic glass was systematically investigated by the numerical method. Simulations on specimens without notches demonstrated that the parameters being determined in this work could reasonably describe the strength asymmetry of tension and compression. Moreover, four samples with different notches were used to numerically investigate the notch effect on global strength and plasticity. A better agreement could also be achieved between current simulations with existing experimental results, compared with another free-volume model. Combined with the free-volume distribution during deformation process, it was proven that the intersection of two major shear bands is the cause for the strength and plasticity enhancement found in sample with two symmetric notches. Besides, strength asymmetry between tension and compression was also found for notched samples. Compressive strengths are accordingly higher than tensile ones. Moreover, with the augment of the aspect ratio, the plasticity for specimens with two symmetric notches was found to increase firstly and then decrease afterwards.

scholarly journals An Experimental and Numerical Study of Ballistic Impacts on a Turbine Casing Material at Varying Temperatures

2011 ◽  
Vol 78 (5) ◽  
Author(s):  
B. Erice ◽  
F. Gálvez ◽  
D. A. Cendón ◽  
V. Sánchez-Gálvez ◽  
T. Børvik
Keyword(s):  
Finite Element ◽  
Thick Plate ◽  
Numerical Study ◽  
Shear Bands ◽  
Mesh Size ◽  
Complex Loading ◽  
Steel Plates ◽  
Explicit Finite Element ◽  
Ballistic Impacts ◽  
Turbine Casing

An experimental and numerical study of ballistic impacts on steel plates at various temperatures (700 °C, 400 °C and room temperature) has been carried out. The motivation for this work is the blade-off event that may occur inside a jet engine turbine. However, as a first attempt to understand this complex loading process, a somewhat simpler approach is carried out in the present work. The material used in this study is the FV535 martensitic stainless steel, which is one of the most commonly used materials for turbine casings. Based on material test data, a Modified Johnson-Cook (MJC) model was calibrated for numerical simulations using the LS-DYNA explicit finite element code. To check the mesh size sensitivity, 2D axisymmetric finite element models with three different mesh sizes and configurations were used for the various temperatures. Two fixed meshes with 64 and 128 elements over the 2 mm thick plate and one mesh with 32 elements over the thickness with adaptive remeshing were used in the simulations. Both the formation of adiabatic shear bands in the perforation process and the modeling of the thermal softening effects at high temperatures have been found crucial in order to achieve good results.

scholarly journals Numerical Study of the Formation of Shear Bands in Soil under Interface Shearing

2017 ◽  
Vol 175 ◽  
pp. 102-109 ◽  
Author(s):  
Huaxiang Zhu ◽  
Wan-Huan Zhou ◽  
Xue-Ying Jing ◽  
Zhen-Yu Yin
Keyword(s):  
Numerical Study ◽  
Shear Bands ◽  
Interface Shearing

FRACTAL PLASTIC SHEAR BANDS

Fractals ◽  
1994 ◽  
Vol 02 (04) ◽  
pp. 567-581 ◽  
Author(s):  
ALEXEI N. B. POLIAKOV ◽  
HANS J. HERRMANN ◽  
YURI YU. PODLADCHIKOV ◽  
STÉPHANE ROUX
Keyword(s):  
Spatial Organization ◽  
Numerical Study ◽  
Shear Bands ◽  
Length Distribution ◽  
Confining Pressure ◽  
Flow Rule ◽  
Plastic Shear ◽  
Scaling Exponents ◽  
High Confining Pressure ◽  
Plastic Flow Rule

We present a numerical study model of shear bands in rocks with a non-associated plastic flow rule. The system drives spontaneously into a state in which the length distribution of shear bands follows a power law and where the spatial organization of the shear bands appears to be fractal. The distribution of local gradients in deviatoric strain rate has different scaling exponents for each moment which we calculate and discuss. Samples of granodiorite from the Pyrenees sheared under high confining pressure are analyzed and their properties compared with the numerical results.

Numerical study of the low-frequency atomic dynamics in a Lennard-Jones glass

1998 ◽  
Vol 77 (2) ◽  
pp. 473-484 ◽  
Author(s):  
M. Sampoli, P. Benassi, R. Dell'Anna,
Keyword(s):  
Numerical Study ◽  
Low Frequency ◽  
Lennard Jones
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