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2006

Mechanical Engineering

Brigham Young University

Grain boundaries

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Lattice-Based Structures For Studying Percolation In Two-Dimensional Grain Networks, Brent L. Adams, John A. Basinger, David T. Fullwood Jan 2006

Lattice-Based Structures For Studying Percolation In Two-Dimensional Grain Networks, Brent L. Adams, John A. Basinger, David T. Fullwood

Faculty Publications

This work was supported primarily by the MRSEC program of the National Science Foundation under DMR-0079996. The applicability of standard lattice percolation models to a random 2-D grain structure is explored. A random network based on the triangle lattice is proposed as a more appropriate model, and results in a higher percolation threshold (0.711 compared with 0.653 for the standard hexagonal lattice). The triple junction constraint inherent in grain boundary structures is subsequently applied to the new network. This results in a lowering of the percolation threshold to 0.686; this is opposite to its effect on the standard hexagonal lattice. …


Extending Taylor Plasticity Theory For Microscopic Slip Transfer Conditions, Brent L. Adams, Ray M. Merrill, John A. Basinger, Bassem S. El-Dasher Jan 2006

Extending Taylor Plasticity Theory For Microscopic Slip Transfer Conditions, Brent L. Adams, Ray M. Merrill, John A. Basinger, Bassem S. El-Dasher

Faculty Publications

This work was supported primarily by the MRSEC Program of the National Science Foundation under DMR-0079996. Most studies in crystal plasticity are based upon Taylor's original 1938 work. Within Taylor's framework the dependence of yield strength on microstructure, beyond lattice orientation, is carried within the critical resolved shear stress for slip. Thus, as the grain size decreases, the critical resolved shear stress is required to increase. This increase in critical resolved shear stress is applied, uniformly across the entire interior of the slipping grains according to the basic assumption of the model (uniform plastic strain or strain rate). It is …