On correct account of finite rotations in finite plasticity theory

1992 ◽  
Vol 8 (3) ◽  
pp. 253-260 ◽  
Author(s):  
V. I. Levitas
Keyword(s):  
Plasticity Theory ◽  
Finite Rotations ◽  
Finite Plasticity ◽  
Correct Account

scholarly journals Evolution of the stiffness tetrad in fiber-reinforced materials under large plastic strain

2020 ◽  
Author(s):  
Martin Weber ◽  
Rainer Glüge ◽  
Holm Altenbach
Keyword(s):  
Plastic Strain ◽  
Plasticity Theory ◽  
Fiber Reinforced ◽  
Large Plastic Strain ◽  
Fiber Reorientation ◽  
Finite Plasticity ◽  
Fiber Reinforced Materials ◽  
Special Cases ◽  
Before And After ◽  
Reinforced Materials

Abstract The main aim of this work is to track the evolution of the stiffness tetrad during large plastic strain. Therefore, the framework of a general finite plasticity theory is developed. Some special cases are examined, and the case of a material plasticity theory is considered more closely. Its main feature is that the elasticity law changes during plastic deformations, for which we develop an approach. As sample materials, we use three types of fiber-reinforced composites. For numerical experiments and verification of the model’s predictions, finite element simulations of representative volume elements for uni-, bi- and tri-directional reinforced materials with periodic boundary conditions are used. From these, we extract the stiffness tetrads before and after large deformations of the material. We quantify the change of the stiffness tetrads due to the fiber reorientation. Finally, we propose an analytical evolution with three parameters that account reasonably well for the evolution of the stiffness tetrad.

‘The moral irrelevance of moral coercion’

2021 ◽  
Author(s):  
Helen Frowe
Keyword(s):  
Correct Account ◽  
Defensive Harm

AbstractAn agent A morally coerces another agent, B, when A manipulates non-epistemological facts in order that B’s moral commitments enjoin B to do what A wants B to do, and B is motivated by these commitments. It is widely argued that forced choices arising from moral coercion are morally distinct from forced choices arising from moral duress or happenstance. On these accounts, the fact of being coerced bears on what an agent may do, the voluntariness of her actions, and/or her accountability for any harms that result from her actions (where accountability includes liability to defensive harm, punishment, blame and compensation). This paper does not provide an account of the wrongness of moral coercion. Rather, I argue that, whatever the correct account of its wrongness, the mere fact of being coerced has no bearing on what the agent may do, on the voluntariness of her action, or her accountability for any resultant harm, compared to otherwise identical cases arising from duress and happenstance.

VARIATIONAL MULTISCALE ANALYSIS OF SOLIDS WITH STRAIN GRADIENT PLASTIC EFFECTS USING MESHFREE APPROXIMATION

2005 ◽  
Vol 02 (04) ◽  
pp. 601-626 ◽  
Author(s):  
JEOUNG-HEUM YEON ◽  
SUNG-KIE YOUN
Keyword(s):  
Strain Gradient ◽  
Partition Of Unity ◽  
Meshfree Method ◽  
Internal Variable ◽  
Plasticity Theory ◽  
Fine Scale ◽  
Meshfree Approximation ◽  
Gradient Effect ◽  
Classical Plasticity ◽  
Variational Form

A meshfree multiscale method is presented for efficient analysis of solids with strain gradient plastic effects. In the analysis of strain gradient plastic solids, localization due to increased hardening of strain gradient effect appears. Chen-Wang theory is adopted, as a strain gradient plasticity theory. It represents strain gradient effects as an internal variable and retains the essential structure of classical plasticity theory. In this work, the scale decomposition is carried out based on variational form of the problem. Coarse scale is designed to represent global behavior and fine scale to represent local behavior and gradient effect by using the intrinsic length scale. From the detection of high strain gradient region, fine scale region is adopted. Each scale variable is approximated using meshfree method. Meshfree approximation is well suited for adaptivity. As a method of increasing resolution, partition of unity based extrinsic enrichment is used. Each scale problem is solved iteratively. The proposed method is applied to bending of a thin beam and bimaterial shear layer and micro-indentation problems. Size effects can be effectively captured in the results of the analysis.

A Study of Microindentation Hardness Tests by Mechanism-based Strain Gradient Plasticity

2000 ◽  
Vol 15 (8) ◽  
pp. 1786-1796 ◽  
Author(s):  
Y. Huang ◽  
Z. Xue ◽  
H. Gao ◽  
W. D. Nix ◽  
Z. C. Xia
Keyword(s):  
Strain Gradient ◽  
Size Dependence ◽  
Plasticity Theory ◽  
Strain Gradient Plasticity ◽  
Gradient Plasticity ◽  
Hierarchical Framework ◽  
Microindentation Hardness ◽  
Dislocation Hardening ◽  
Hardness Tests ◽  
Micro Indentation

We recently proposed a theory of mechanism-based strain gradient (MSG) plasticity to account for the size dependence of plastic deformation at micron- and submicronlength scales. The MSG plasticity theory connects micron-scale plasticity to dislocation theories via a multiscale, hierarchical framework linking Taylor's dislocation hardening model to strain gradient plasticity. Here we show that the theory of MSG plasticity, when used to study micro-indentation, indeed reproduces the linear dependence observed in experiments, thus providing an important self-consistent check of the theory. The effects of pileup, sink-in, and the radius of indenter tip have been taken into account in the indentation model. In accomplishing this objective, we have generalized the MSG plasticity theory to include the elastic deformation in the hierarchical framework.

Developing the concept of the strain rate intensity factor in plasticity theory

2003 ◽  
Vol 48 (3) ◽  
pp. 131-133 ◽  
Author(s):  
S. E. Aleksandrov ◽  
R. V. Goldshtein ◽  
E. A. Lyamina
Keyword(s):  
Intensity Factor ◽  
Strain Rate ◽  
Plasticity Theory ◽  
Strain Rate Intensity Factor ◽  
Rate Intensity ◽  
Strain Rate Intensity

Asymmetric crystal plasticity theory for the evolution of polycrystal microstructures

2012 ◽  
Vol 15 (1-2) ◽  
pp. 58-68 ◽  
Author(s):  
Peter V. Trusov ◽  
P. S. Volegov ◽  
A. Yu. Yants
Keyword(s):  
Crystal Plasticity ◽  
Plasticity Theory ◽  
Crystal Plasticity Theory
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