Abstract

The miniaturization of structural components to the sub-micrometer scale has created a significant challenge when attempting to engineer such structures using conventional models and simulation tools that are based solely on continuum approaches. Although there has been progress in strain-gradient continuum theories to model the mechanical behavior of metallic systems at small length scales, these theories fail to represent the variety of physical mechanisms involved in dislocation motion in small volumes where dislocations are scarce and the behavior can be stochastic. The major difficulty in these theories lies in the notion that physical mechanisms which arise from dislocation motion that occur at the micrometer scale, and are intrinsically discrete events, can be represented in the form of continuum variables at the macro-meter length scale. This drastic jump between scales may be statistically meaningful for relatively large volumes but loses all sense when the volume is so small such that dislocations become in short supply. This situation, in turn, has brought about the need to develop novel multiscale material models and simulation tools that may enable engineers to design and analyze multiscale structures at such small scales. In parallel, this also necessitates the need to develop novel experimental techniques to determine and verify mechanical properties at the sub-micrometer scale for use in such models. In this presentation we will discuss a multiscale method bridging discrete dislocation dynamics with continuum plasticity, and how we use this approach not only to investigate small scale deformation phenomena, but also to develop a dislocation-based mesoscale crystal plasticity model, including dislocation densities, size effects, hardening laws based on dislocation-dislocation interactions, and a set of mechanisms-based evolution laws which include stochastic effects that are observed in experiments and may arise from initial microstructure/defect conditions.

Bio

Zbib (born 1958) has over 27 years of experience in academia, as an educator, researcher and administrator. He received his doctor of philosophy in Mechanical Engineering and Engineering Mechanics from Michigan Technological University (MTU) in 1987 in the area of solid mechanics. He was appointed to his present post at the School of Mechanical and Materials Engineering at Washington State University (WSU) in 1988, and was promoted to the rank of Professor in August 1998. He is a Lab Fellow with Joint Appoint at Pacific Northwest National Laboratory since Aug 2011.
Zbib’s research is in the areas of materials and mechanics with a focus on the thermo-mechanical behavior of materials and materials. In materials research he works on problems in the theory of dislocation, dislocation dynamics, defects, crystal plasticity, radiation effects, and materials for high energy efficiency. In mechanics research he is interested in damage and fracture, multiscale modeling and analysis, plasticity, composites, and materials instabilities. His work involves investigating phenomena that occur at various length scales.

On the small end of the length scale spectrum (nanometer to micrometer) his work includes investigating the physical characteristics and mechanical performance of metals and composites with implications to advanced high strength steel, magnesium alloys, nanolaminates, nanocomposites, nanostructured materials and thin films, such as those used in micromechanical systems, microelectronics, and medical diagnostics. On the large end of the length scale spectrum (micrometer to macrometer) he investigates the behavior of metals and geological materials under extreme conditions, such as shockwaves, metal forming and high speed machining, superplastic forming, as well as earthquake and soil engineering. His research has been funded by many agencies, including the US National Science foundation, the US Army Research Office, Lawrence Livermore National Laboratory, Los Alamos National Laboratory, Pacific Northwest National Laboratory, ALCOA, the US National Institute of Standard and Technology, Sandia National Laboratory, the US Department of Energy, the Washington Technology Center, QNRF.

Zbib is a member in the Lebanese Academy of Sciences, AAAS, ASME, MRS, APS, TMS, SEE, and AAM. His service record includes, chairing and organizing many conferences, and organizing and chairing numerous symposia and sessions at ASME, MRS, SES, IUAM and other national and international meetings. He is Editor of the Journal of Engineering Materials and Technology. He is a member of the Advisory Board of the International Journal of Plasticity; Member of the Board of Review of Metallurgical and Materials Transactions A; Member of the International Advisory Board: Materials Science Research International, Japan. He was the chair of the joint ASME MD-AMD committee on constitutive equations and serves on the ASME-MD Executive Committee.

Zbib is a ASME Fellow, AAAS Fellow, member of the Academy of Mechanical Engineering and Engineering Mechanics of Michigan Tech Univ., recipient of the 2010 Khan International Award from the Int. Sym. Of Plasticity, the 2003 Computational Mechanics Achievement Award from the Japanese Society of Mechanical Engineers, the 1994 Research Excellence Award from the Collage of Engineering at WSU, the 1994 and 2000 Research award from MME at WSU. He held two Japanese fellowships, the 1994 Research Award from the MME Department, and he was invited to deliver many Keynote lectures. He received the NSF Research Initiation Award, was nominated for the ASEE Dow Young Faculty Award, and received a NATO Fellowship.
Zbib’s publication record includes 12 edited books and over 225 technical articles.

Please see the Colloquium Announcement for more details.

An informal coffee & cookie reception will be held prior to the lecture at 2:30 p.m. in the AAE/ARMS undergraduate lounge (directly in front of ARMS 3rd floor elevators).