Numerical analysis of the indentation size effect using a strain gradient crystal plasticity model

2014 ◽  
Vol 82 ◽  
pp. 314-319 ◽  
Author(s):  
D. González ◽  
J. Alkorta ◽  
J.M. Martínez-Esnaola ◽  
J. Gil Sevillano
Keyword(s):  
Numerical Analysis ◽  
Size Effect ◽  
Crystal Plasticity ◽  
Strain Gradient ◽  
Indentation Size Effect ◽  
Plasticity Model ◽  
Indentation Size ◽  
Crystal Plasticity Model

Experimental Verification of the Strain-Gradient Plasticity Model for Indentation

2005 ◽  
Vol 20 (11) ◽  
pp. 3150-3156
Author(s):  
Linmao Qian ◽  
Hui Yang ◽  
Minhao Zhu ◽  
Zhongrong Zhou
Keyword(s):  
Size Effect ◽  
Yield Stress ◽  
Strain Gradient ◽  
Indentation Size Effect ◽  
Linear Increase ◽  
Strain Gradient Plasticity ◽  
Plasticity Model ◽  
Gradient Plasticity ◽  
Indentation Size ◽  
Tensile Yield Stress

The indentation size effect of pure iron samples with various pre-plastic tensile strains has been experimentally investigated and analyzed. With the increase in the strain, the indentation size effect of iron samples becomes weak, accompanied by the multiplication of the statistically stored dislocations. All of the hardness (H) versus indentation depth (h) curves fit the strain-gradient plasticity model for indentation of Nix and Gao well. Two fitting parameters, the hardness in the limit of infinite depth (H0) and the characteristic length (h*), were obtained for each curve. The hardness (H0) of iron samples can also be estimated as the microhardness (H) at a very large depth, h ≅ 10h*. Both the fitted H0 and the measured H0′ increase linearly with the tensile yield stress σy of iron samples, indicating a dependence of H0 on the statistically stored dislocation density through σy. Furthermore, 1/√h* shows a linear increase with the tensile yield stress σy, which also agrees qualitatively with the general prediction of the Nix and Gao theory. Therefore, our experiments and analysis demonstrate that the strain-gradient plasticity model for indentation of Nix and Gao can interpret the indentation size effect with satisfied precision.

Tunable surface boundary conditions in strain gradient crystal plasticity model

2020 ◽  
Vol 145 ◽  
pp. 103393
Author(s):  
Sibo Yuan ◽  
Laurent Duchêne ◽  
Clément Keller ◽  
Eric Hug ◽  
Anne-Marie Habraken
Keyword(s):  
Boundary Conditions ◽  
Crystal Plasticity ◽  
Strain Gradient ◽  
Surface Boundary ◽  
Plasticity Model ◽  
Surface Boundary Conditions ◽  
Crystal Plasticity Model

Meshfree Analysis of Higher-Order Gradient Crystal Plasticity Using Nodal Integration

2019 ◽  
Vol 794 ◽  
pp. 214-219
Author(s):  
Tota Niiro ◽  
Yuichi Tadano
Keyword(s):  
Size Effect ◽  
Crystal Plasticity ◽  
Meshfree Method ◽  
Higher Order ◽  
Integration Scheme ◽  
Plasticity Model ◽  
The Finite Element Method ◽  
Nodal Integration ◽  
Crystal Plasticity Model ◽  
Meshfree Analysis

The size effect of metallic materials is one of the important factors for understanding characteristics of material. The higher-order gradient crystal plasticity is a powerful model for describing the size effect. However, it is known that the finite element method sometimes provides an improper solution. In this study, we analyze the higher-order gradient crystal plasticity model using a meshfree method, and a nodal integration scheme is introduced to improve the analysis accuracy. The effectiveness and stability of the meshfree method for the higher-order gradient crystal plasticity model are quantitatively discussed.

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