Size Effects in Plasticity

Dr. Voyiadjis is a Member of the European Academy of Sciences, and Foreign Member of both the Polish Academy of Sciences, and the National Academy of Engineering of Korea. George Z. Voyiadjis is the Boyd Professor at the Louisiana State University, in the Department of Civil and Environmental Engineering. This is the highest professorial rank awarded by the Louisiana State University System. He is also the holder of the Freeport-MacMoRan Endowed Chair in Engineering. He joined the faculty of Louisiana State University in 1980. He is currently the Chair of the Department of Civil and Environmental Engineering. He holds this position since February of 2001. He also served from 1992 to 1994 as the Acting Associate Dean of the Graduate School. He currently also serves since 2012 as the Director of the Louisiana State University Center for GeoInformatics (LSU C4G; http://c4gnet.lsu.edu/c4g/ ).Voyiadjis’ primary research interest is in plasticity and damage mechanics of metals, metal matrix composites, polymers and ceramics with emphasis on the theoretical modeling, numerical simulation of material behavior, and experimental correlation. Research activities of particular interest encompass macro-mechanical and micro-mechanical constitutive modeling, experimental procedures for quantification of crack densities, inelastic behavior, thermal effects, interfaces, damage, failure, fracture, impact, and numerical modeling. Dr. Voyiadjis’ research has been performed on developing numerical models that aim at simulating the damage and dynamic failure response of advanced engineering materials and structures under high-speed impact loading conditions. This work will guide the development of design criteria and fabrication processes of high performance materials and structures under severe loading conditions. Emphasis is placed on survivability area that aims to develop and field a contingency armor that is thin and lightweight, but with a very high level of an overpressure protection system that provides low penetration depths. The formation of cracks and voids in the adiabatic shear bands, which are the precursors to fracture, are mainly investigated. He has two patents, over 332 refereed journal articles and 19 books (11 as editor) to his credit. He gave over 400 presentations as plenary, keynote and invited speaker as well as other talks. Over sixty two graduate students (37 Ph. D.) completed their degrees under his direction. He has also supervised numerous postdoctoral associates. Voyiadjis has been extremely successful in securing more than $30.0 million in research funds as a principal investigator/investigator from the National Science Foundation, the Department of Defense, the Air Force Office of Scientific Research, the Department of Transportation, National Oceanic and Atmospheric Administration (NOAA), and major companies such as IBM and Martin Marietta. Mohammadreza Yaghoobi is a research faculty in the Material Science and Engineering Department at University of Michigan, Ann Arbor. His primary research interest is in multiscale computational plasticity and damage mechanics of crystalline materials, composites, and ceramics with emphasis on the theoretical modeling, numerical simulation of material behavior, and experimental correlation. Research activities of particular interest includes modelling at different length scales including atomistic simulation, crystal plasticity finite element method, and local and nonlocal continuum plasticity. Central to his research is serving as a lead developer of PRISMS-Plasticity software, which is an open-source parallel 3-D crystal plasticity and continuum plasticity finite element code.

• 1. Introduction: Size effects in materials2. Nonlocal continuum plasticity3. Nonlocal crystal plasticity4. Discrete dislocation dynamics5. Molecular dynamics6. Future evolution: Multiscale modeling framework to develop a physically based nonlocal plasticity model for crystalline materials