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oai:www.ideals.illinois.edu:2142/72229 2023-07-11 col_2142_5131 col_2142_14787 com_2142_5130 com_2142_9630 com_2142_234

Beaudoin, Armand J. Mach, Justin C. 2014-12-17T21:26:13Z 2014-12-17T21:26:13Z 10000-01-01 2009 2009 Classical plasticity models evolve state variables in a spatially independent manner through (local) ordinary differential equations, such as in the update of the rotation field in crystal plasticity. This approach emanates from how the deformation has been described, e.g. the multiplicative decomposition of the deformation gradient. In the present work, a continuity condition is derived for the elastic spin field from a conservation law for Burgers vector content---a consequence of an averaged field theory of dislocation mechanics. This results in a nonlocal evolution equation for the rotation field in rigid viscoplasticity. The continuity condition provides a theoretical basis for assumptions of co-rotation models of crystal plasticity. The prediction of texture evolution is improved without constitutive enhancements. This provides evidence for the importance of continuity in modeling of classical plasticity. Bulk rolling texture evolution predictions for f.c.c. metals exhibit a weaker overall intensity with a more uniform beta fiber. Single grain simulations show evidence of grain splitting and locally larger rotations with an average rotation less than a Taylor model prediction. Continuous elastic rotation fields with sharp gradients (as in grain splitting) are computationally demonstrated within rigid viscoplasticity and non-singular dislocation distributions are calculated from these rotation fields. Computational evidence is shown for the enhancement of stress fields in the vicinity of delamination-prone grain boundaries. All of these results suggest that even the problem of size-independent macroscopic plasticity is spatially nonlocal in nature. Made available in DSpace on 2014-12-17T21:26:13Z (GMT). No. of bitstreams: 1 3363028.pdf: 1625934 bytes, checksum: d89b4b3c796704958017f8f1f29a22ff (MD5) Previous issue date: 2009 Embargo set by: Seth Robbins for item 72397 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 97 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009. http://hdl.handle.net/2142/72229 (UMI)AAI3363028 Engineering, Mechanical Continuity in Rigid Viscoplastic Flow text Mechancial Engineering Mechanical Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.