Dislocation density-based plasticity model from massive discrete dislocation dynamics database
Journal Article
·
· Journal of the Mechanics and Physics of Solids
- Stanford Univ., CA (United States)
- Rutgers Univ., Piscataway, NJ (United States)
- Stanford Univ., CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
In this work, we present a dislocation density-based strain hardening model for single crystal copper through a systematic coarse-graining analysis of more than 200 discrete dislocation dynamics (DDD) simulations of plastic deformation under uniaxial tension. The proposed constitutive model has two components: a generalized Taylor relation connecting resolved shear stresses to dislocation densities on individual slip systems, and a generalized Kocks-Mecking model for dislocation multiplication. The DDD data strongly suggests a logarithmic dependence of flow stress on the plastic shear strain rate on each slip system, and, equivalently, an exponential dependence of the plastic shear strain rate on the resolved shear stress. Hence the proposed generalized Taylor relation subsumes the Orowan relation for plastic flow. The DDD data also calls for a correction to the Kocks-Mecking model of dislocation multiplication to account for the increase of dislocation density on slip systems with negligible plastic shear strain rate. This is accomplished by allowing the multiplication rate on each slip system to include contributions from the plastic strain rates of the two coplanar slip systems. The resulting constitutive model successfully captures the strain hardening rate dependence on the loading orientation as predicted by the DDD simulations, which is also consistent with existing experiments.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); USDOE; USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
- Grant/Contract Number:
- AC52-07NA27344; SC0010412
- OSTI ID:
- 1785910
- Alternate ID(s):
- OSTI ID: 1776116
- Report Number(s):
- LLNL-JRNL--809835; 1015833
- Journal Information:
- Journal of the Mechanics and Physics of Solids, Journal Name: Journal of the Mechanics and Physics of Solids Vol. 145; ISSN 0022-5096
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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