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Modeling dislocation sources and size effects at initial yield in continuum plasticity

Puri, Saurabh and Roy, Anish and Acharya, Amit and Dimiduk, Dennis (2009) Modeling dislocation sources and size effects at initial yield in continuum plasticity. Journal of Mechanics of Materials and Structures , 4 (9). pp. 1603-1618. ISSN 1559-3959 .

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Size effects at initial yield (prior to stage II) of idealized micron-sized specimens are modeled within a continuum model of plasticity. Two different aspects are considered: specification of a density of dislocation sources that represent the emission of dislocation dipoles, and the presence of an initial, spatially inhomogeneous excess dislocation content. Discreteness of the source distribution appears to lead to a stochastic response in stress-strain curves, with the stochasticity diminishing as the number of sources increases. Variability in stress-strain response due to variations of source distribution is also shown. These size effects at initial yield are inferred to be due to physical length scales in dislocation mobility and the discrete description of sources that induce internal-stress-related effects, and not due to length-scale effects in the mean-field strain-hardening response (as represented through a constitutive equation).

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Additional Information:© 2009 Mathematical Sciences Publishers. Received 16 Jul 2008. Revised 14 Mar 2009. Accepted 4 Jun 2009. We thank Armand Beaudoin for discussions on dynamical sensitivity. Support for this work from the National Science Foundation (Grant number: DMI-0423304), the Dowd-ICES Fellowship at CMU to Saurabh Puri, and the Metallic Materials Division of the AFRL at WPAFB is gratefully acknowledged.
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Dowd-ICES Fellowship at Carnegie Mellon University (CMU)UNSPECIFIED
Metallic Materials Division of the Air Force Research Laboratory (AFRL) at Wright-Patterson Air Force Base (WPAFB)UNSPECIFIED
Subject Keywords:continuum plasticity; dislocations; finite elements
Issue or Number:9
Record Number:CaltechAUTHORS:20100218-143334873
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17526
Deposited By: Tony Diaz
Deposited On:19 Feb 2010 18:47
Last Modified:03 Oct 2019 01:29

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