@article{lee_zikry_2014, title={Microstructurally induced computational and material instabilities}, volume={52}, ISSN={["1879-2154"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84888199883&partnerID=MN8TOARS}, DOI={10.1016/j.ijplas.2013.06.011}, abstractNote={Abstract A dislocation-density based finite strain crystal plasticity finite element model and an hourglass strain measure orthogonal to the linear velocity field were used to investigate microstructural effects on deformation and hourglass instability. An aluminum aggregate was modeled in quasi-static plane strain tension and compression, and the effects of the presence of manganese-based dispersed particles were investigated. Both local plastic deformation and the presence of these dispersed particles can trigger hourglass instabilities, which can be mistaken for deformation or failure modes. These hourglass modes occur due to the difference in the deformability of neighboring elements or regions and the associated energy modes associated with hourglassing, and the proposed computational methodology can be used to delineate between failure modes and numerical instabilities.}, journal={INTERNATIONAL JOURNAL OF PLASTICITY}, author={Lee, W. M. and Zikry, M. A.}, year={2014}, month={Jan}, pages={95–104} }
 @article{lee_zikry_2012, title={Dispersed particle and triple junction interactions in aluminum alloys}, volume={535}, ISSN={["0921-5093"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84856525455&partnerID=MN8TOARS}, DOI={10.1016/j.msea.2011.12.081}, abstractNote={The interrelated effects of dispersed particle interfaces and grain-boundary (GB) misorientations on the dynamic compressive deformation of high strength aluminum alloys have been investigated using an eigenstrain-based formulation coupled with dislocation-density based crystalline plasticity and a microstructurally based finite element framework. This formulation, which accounts for the unrelaxed plastic strains associated with the interfacial behavior of dispersed particles, such as Orowan looping, was used to model an aluminum tri-crystal with different distributions of dispersed particles and GB misorientations. Slip was relatively homogeneous and associated with initially preferential slip planes for low angle random GB misorientations. Particle dispersion had a greater effect on the deformation behavior for the high angle random GB misorientation tri-crystal, with dislocation density generation at the particle–matrix interface resulting in localized particle-controlled shear banding, which can inhibit transgranular shear banding caused by the triple junctions. Larger dispersed particles led to higher stress concentrations at the triple junction and higher tensile pressures at the particle–matrix interfaces.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Lee, W. M. and Zikry, M. A.}, year={2012}, month={Feb}, pages={264–273} }
 @article{lee_zikry_2012, title={High strain-rate modeling of the interfacial effects of dispersed particles in high strength aluminum alloys}, volume={49}, ISSN={["1879-2146"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84865721891&partnerID=MN8TOARS}, DOI={10.1016/j.ijsolstr.2012.07.003}, abstractNote={The interfacial effects of dispersed particles on the dynamic deformation of high strength aluminum alloys have been investigated using an eigenstrain-based formulation coupled with dislocation-density based crystalline plasticity and a microstructurally based finite element framework. This accounts for the unrelaxed plastic strains associated with the interfacial behavior of dispersed particles, such as Orowan looping. Particle spacing had a significant effect on the distribution of plastic shear slip, with localization occurring between the particles for smaller particle spacing. The eigenstress field associated with larger particles led to longer-range interaction of pressure fields, which can promote void coalescence for nucleated voids at the particle-matrix interface. Grain orientation also had a significant effect on the behavior associated with the particles, with plastic shear slip localizing at the particle-matrix interfaces for low angle grain-boundary (GB) misorientations, and at GBs and GB junctions for high angle GB misorientations.}, number={23-24}, journal={INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES}, author={Lee, W. M. and Zikry, M. A.}, year={2012}, month={Nov}, pages={3291–3300} }
 @article{lee_zikry_2012, title={Modeling the interfacial plastic strain incompatibilities associated with dispersed particles in high strength aluminum alloys}, volume={60}, ISSN={["1359-6454"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84862802552&partnerID=MN8TOARS}, DOI={10.1016/j.actamat.2011.11.058}, abstractNote={A new formulation based on an eigenstrain representation of Orowan looping was developed, and was coupled with a dislocation density based crystalline plasticity formulation and a specialized finite element framework to model the unrelaxed plastic strain and interfacial behavior associated with dispersed particles in high strength aluminum alloys. This representation accounts for the increased stresses associated with Orowan looping at interfacial locations, where extra half-planes due to Orowan loops occur at opposite particle corners. Plastic relaxation of the Orowan loops was modeled using the incompatibility of the lattice rotations between the particles and the alloy matrix. The predictions indicate that the orientations and morphologies of the particles with respect to the most active slip plane are the critical factors in the relaxation of the eigenstrains associated with the loops.}, number={4}, journal={ACTA MATERIALIA}, author={Lee, W. M. and Zikry, M. A.}, year={2012}, month={Feb}, pages={1669–1679} }
 @article{salem_lee_bodelot_ravichandran_zikry_2012, title={Quasi-Static and High-Strain-Rate Experimental Microstructural Investigation of a High-Strength Aluminum Alloy}, volume={43A}, ISSN={["1073-5623"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84862807927&partnerID=MN8TOARS}, DOI={10.1007/s11661-011-1064-6}, number={6}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Salem, H. G. and Lee, William M. and Bodelot, Laurence and Ravichandran, G. and Zikry, M. A.}, year={2012}, month={Jun}, pages={1895–1901} }
 @article{elkhodary_lee_sun_brenner_zikry_2011, title={Deformation mechanisms of an Omega precipitate in a high-strength aluminum alloy subjected to high strain rates}, volume={26}, ISSN={["0884-2914"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-80054905299&partnerID=MN8TOARS}, DOI={10.1557/jmr.2010.29}, abstractNote={Abstract}, number={4}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Elkhodary, K. and Lee, W. and Sun, L. P. and Brenner, D. W. and Zikry, M. A.}, year={2011}, month={Feb}, pages={487–497} }
 @article{lee_zikry_2011, title={Microstructural Characterization of a High-Strength Aluminum Alloy Subjected to High Strain-Rate Impact}, volume={42A}, ISSN={["1543-1940"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79954431266&partnerID=MN8TOARS}, DOI={10.1007/s11661-010-0476-z}, number={5}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Lee, W. M. and Zikry, M. A.}, year={2011}, month={May}, pages={1215–1221} }