An Explanation for the Size-Effect in Machining Using Strain Gradient Plasticity

2004 ◽  
Vol 126 (4) ◽  
pp. 679-684 ◽  
Author(s):  
Suhas S. Joshi ◽  
Shreyes N. Melkote
Keyword(s):  
Size Effect ◽  
Strain Gradient ◽  
Shear Plane ◽  
Strain Gradient Plasticity ◽  
Gradient Plasticity ◽  
Gradient Density ◽  
Experimental Values ◽  
Material Length Scale ◽  
Material Length ◽  
Shear Energy

This paper aims to explain the size-effect in the Primary Deformation Zone (PDZ) in machining using strain gradient plasticity theory. Considering a parallel-sided shear zone configuration, models are formulated for the evaluation of strain gradient, density of geometrically necessary dislocations, shear strength and the specific shear energy. The analysis of deformation in the PDZ shows that the length of the shear plane represents the fundamental material length scale governing the size-effect. It also provides an estimate of the lower bound on the size-effect observed in the specific shear energy. The general trends predicted by the model are shown to agree well with the experimental values obtained from the literature.

The correlation between the internal material length scale and the microstructure in nanoindentation experiments and simulations using the conventional mechanism-based strain gradient plasticity theory

2009 ◽  
Vol 24 (3) ◽  
pp. 1197-1207 ◽  
Author(s):  
B. Backes ◽  
Y.Y. Huang ◽  
M. Göken ◽  
K. Durst
Keyword(s):  
Yield Stress ◽  
Strain Gradient ◽  
Plasticity Theory ◽  
Strain Gradient Plasticity ◽  
Length Scale ◽  
Gradient Plasticity ◽  
Hardening Behavior ◽  
Material Length Scale ◽  
Material Length ◽  
Strain Gradient Plasticity Theory

In the present work a new equation to determine the internal material length scale for strain gradient plasticity theories from two independent experiments (uniaxial and nanoindentation tests) is introduced. The applicability of the presented equation is verified for conventional grained as well as for ultrafine-grained copper and brass with different amounts of prestraining. A significant decrease of the experimentally determined internal material length scale is found for increasing dislocation densities due to prestraining. Conventional mechanism strain gradient plasticity theory is used for simulating the indentation response, using experimentally determined material input data as the yield stress, the work-hardening behavior and the internal material length scale. The work-hardening behavior and the yield stress were taken from the uniaxial experiments, whereas the internal material length scale was calculated using the yield stress from the uniaxial experiment, the macroscopic hardness H0 and the length scale parameter h* following from the nanoindentation experiment. A good agreement between the measured and calculated load–displacement curve and the hardness is found independent of the material and the microstructure.

Length Scale in Solder Joints Materials

2006 ◽  
Author(s):  
Juan Gomez ◽  
Cemal Basaran
Keyword(s):  
Strain Gradient ◽  
Constitutive Models ◽  
Strain Gradient Plasticity ◽  
Length Scale ◽  
Gradient Plasticity ◽  
Additional Material ◽  
Size Dependent ◽  
Dependent Behavior ◽  
Material Length Scale ◽  
Material Length

Strain gradient plasticity theories that have emerged during recent years to provide an explanation for size dependent behavior exhibited by some materials have also created a need for additional material parameters. In this study on Pb/Sn solder alloys the material length scale, which is needed for use in strain gradient plasticity type constitutive models, is determined. The value of length scale is in agreement with values available in the literature for different materials like copper, nickel and aluminum.

Determination of Strain Gradient Plasticity Length Scale for Microelectronics Solder Alloys

2006 ◽  
Vol 129 (2) ◽  
pp. 120-128 ◽  
Author(s):  
Juan Gomez ◽  
Cemal Basaran
Keyword(s):  
Strain Gradient ◽  
Constitutive Models ◽  
Strain Gradient Plasticity ◽  
Length Scale ◽  
Gradient Plasticity ◽  
Solder Alloys ◽  
Additional Material ◽  
Dependent Behavior ◽  
Material Length Scale ◽  
Material Length

Strain gradient plasticity theories that have emerged during recent years to provide an explanation for size dependent behavior exhibited by some materials have also created a need for additional material parameters. In this study on Pb∕Sn solder alloys’ material length scale, which is needed for use in strain gradient plasticity type constitutive models, is determined. The value of length scale is in agreement with values available in literature for different materials like copper, nickel, and aluminum.

Novel analysis for nanoindentation size effect using strain gradient plasticity

2005 ◽  
Vol 53 (10) ◽  
pp. 1135-1139 ◽  
Author(s):  
Hunkee Lee ◽  
Seonghyun Ko ◽  
Junsoo Han ◽  
Hyunchul Park ◽  
Woonbong Hwang
Keyword(s):  
Size Effect ◽  
Strain Gradient ◽  
Strain Gradient Plasticity ◽  
Gradient Plasticity
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