Quantum-confined strain gradient effect in semiconductor nanomembranes

2014 ◽  
Vol 90 (19) ◽  
Author(s):  
R. Binder ◽  
B. Gu ◽  
N. H. Kwong
Keyword(s):  
Strain Gradient ◽  
Gradient Effect ◽  
Quantum Confined

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.

Gradient of Soil Constitutive Model

2010 ◽  
Vol 168-170 ◽  
pp. 1126-1129
Author(s):  
Wen Xu Ma ◽  
Ying Guang Fang
Keyword(s):  
Plastic Strain ◽  
Strain Gradient ◽  
Soil Analysis ◽  
Natural Material ◽  
Flow Rule ◽  
The Finite Element Method ◽  
Gradient Effect ◽  
Non Local ◽  
Associated Flow Rule ◽  
Plastic Strain Gradient

For the soil is a very complex natural material, significant strain gradient effect exist in soil analysis. Based on the "gradient" phenomenon, we add the plastic strain gradient hardening item into the traditional Cambridge yield surface. By using the consistency conditions and associated flow rule, we get the explicit expression of plastic strain gradient stiffness matrix. And the finite element method of plastic strain gradient is also shown in this article. Plastic strain gradient is actually a phenomenological non-local model containing microstructure information of the material. It may overcome the difficulties in simulating the gradient phenomenon by traditional mechanical model.

Linear strain-gradient effect on the energy bandgap in bent CdS nanowires

Nano Research ◽  
2010 ◽  
Vol 4 (3) ◽  
pp. 308-314 ◽  
Author(s):  
Qiang Fu ◽  
Zi Yue Zhang ◽  
Liangzhi Kou ◽  
Peicai Wu ◽  
Xiaobing Han ◽  
...  
Keyword(s):  
Strain Gradient ◽  
Linear Strain ◽  
Gradient Effect ◽  
Energy Bandgap ◽  
Cds Nanowires

Length-Scale-Dependent Micromechanical Modeling for Precipitate Hardening in Inconel 718 Superalloy

2021 ◽  
Vol 315 ◽  
pp. 84-89
Author(s):  
Chang Feng Wan ◽  
Dong Feng Li ◽  
Hai Long Qin ◽  
Ji Zhang ◽  
Zhong Nan Bi
Keyword(s):  
Dislocation Density ◽  
Strain Gradient ◽  
Inconel 718 ◽  
Micromechanical Modeling ◽  
Fe Model ◽  
Gradient Effect ◽  
Fine Mesh ◽  
Geometrically Necessary Dislocation ◽  
In718 Superalloy ◽  
Inconel 718 Superalloy

In this paper, a micromechanical finite element (FE) model has been proposed to investigate the effect of the nanoscale precipitates on the development of microplasticity for Inconel 718 (IN718) superalloy. A strain gradient crystal plasticity formulation has been developed with the considerations of the evolution of statistically stored dislocation density and geometrically necessary dislocation density. The mesh convergence has been examined, showing that sufficiently fine mesh is required in the FE model. The results show that the model with strain gradient effect incorporated shows less peak plastic strain and higher value of dislocation density than the model with no strain gradient effect. The present study indicates that the strain hardening process at the scale of strengthening precipitate is mainly governed by the evolution of geometrically necessary dislocation densities.

Strain-Gradient Effect in Gas Sensors Based on Three-Dimensional Hollow Molybdenum Disulfide Nanoflakes

2017 ◽  
Vol 9 (50) ◽  
pp. 43799-43806 ◽  
Author(s):  
Min-A Kang ◽  
Jin Kyu Han ◽  
Sam Yeon Cho ◽  
Sang Don Bu ◽  
Chong-Yun Park ◽  
...  
Keyword(s):  
Molybdenum Disulfide ◽  
Gas Sensors ◽  
Strain Gradient ◽  
Three Dimensional ◽  
Gradient Effect

Crack tip field andJ-integral with strain gradient effect

2004 ◽  
Vol 20 (3) ◽  
pp. 228-237 ◽  
Author(s):  
Xia Song ◽  
Wang Tzuchiang ◽  
Chen Shaohua
Keyword(s):  
Strain Gradient ◽  
Crack Tip ◽  
Crack Tip Field ◽  
Gradient Effect
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