Stress/strain gradient plasticity model for size effects in heterogeneous nano-microstructures

2017 ◽  
Vol 97 ◽  
pp. 46-63 ◽  
Author(s):  
Hao Lyu ◽  
Mehdi Hamid ◽  
Annie Ruimi ◽  
Hussein M. Zbib
Keyword(s):  
Strain Gradient ◽  
Size Effects ◽  
Strain Gradient Plasticity ◽  
Plasticity Model ◽  
Gradient Plasticity ◽  
Stress Strain

scholarly journals A strain gradient plasticity model of porous single crystal ductile fracture

2021 ◽  
pp. 104606
Author(s):  
Jean-Michel Scherer ◽  
Jacques Besson ◽  
Samuel Forest ◽  
Jérémy Hure ◽  
Benoît Tanguy
Keyword(s):  
Single Crystal ◽  
Ductile Fracture ◽  
Strain Gradient ◽  
Strain Gradient Plasticity ◽  
Plasticity Model ◽  
Gradient Plasticity

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.

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