Low Order Finite Element Modeling of Size Effects in Micro Structured Materials Based on Strain Gradient Plasticity

2011 ◽  
Author(s):  
Moon Shik Park ◽  
Yeong Sung Suh ◽  
Seung Song
Keyword(s):  
Finite Element ◽  
Strain Gradient ◽  
Size Effects ◽  
Strain Gradient Plasticity ◽  
Dislocation Model ◽  
Gradient Plasticity ◽  
Structured Materials ◽  
Close Proximity ◽  
Micro Indentation ◽  
Low Order

A low order finite element method using theory of strain gradient plasticity along with Taylor dislocation model was developed to evaluate size effects occurring in micro structured materials. The gradient is evaluated in the framework of nonlinear incremental analysis where plastic strains are calculated and averaged at nodes then interpolated and differentiated. The proposed method was verified by solving typical size effect problems such as micro-bending, micro-indentation, and tensile test of a particle-reinforced metal matrix composite. The predicted results show clear length scale effect and close proximity to the respective experimental results.

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.

Strain Gradient Plasticity: An Application to Plastic Flow Localization Analysis

2016 ◽  
Vol 725 ◽  
pp. 41-46
Author(s):  
Mitsutoshi Kuroda
Keyword(s):  
Finite Element ◽  
Plastic Flow ◽  
Strain Gradient ◽  
Strain Gradient Plasticity ◽  
Gradient Plasticity ◽  
Flow Localization ◽  
Element Analysis ◽  
Plastic Flow Localization ◽  
Plane Strain Tension ◽  
Localization Analysis

In this paper, strain gradient plasticity theory is extended to include the corner-like effect that is inherent in crystal plasticity. The predictive feature of the extended theory is examined via finite element analysis of a constrained simple shear problem and a plane-strain tension problem involving plastic flow localization. Numerical issues with respect to finite element formulations are also discussed.

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