Abstract:

A micromechanical framework is proposed in order to predict the deformation responses of particle-reinforced metal matrix composites by invoking essential features of dislocation plasticity. First, within the framework of probabilistic micromechanical formulation, the damage induced by the manufacturing process and by the external mechanical loading in the presence of thermal residual stress is considered. Subsequently, the effective elastic moduli of four-phase composites, consisting of a ductile matrix and randomly located spherical intact or damaged particles are derived. Further, the size-dependent plastic deformation behaviors of particle-reinforced metal matrix composites are predicted with a micromechanics-based dislocation theory. Specifically, the density of dislocations due to the thermal contraction mismatch and the plastic deformation mismatch are taken into consideration within the micromechanical framework to account for the dislocation strengthening. In order to predict the overall elastoplastic damage behavior of composites, a hybrid size-dependent effective yield function is proposed on the basis of ensemble-volume averaging procedure and the modified matrix yield strength. The comparisons between the theoretical predictions and the available experimental data will illustrate the capability of proposed framework.

Biography:

Prof. Ju received his Ph.D. (1986) from UC Berkeley. He is the Chair of Structural Engineering & Mechanics Program at UCLA, and served as the Department Chair. Prof. Ju served as an Associate Editor for ASME Journal of Engineering Materials & Technology, and for ASME Journal of Applied Mechanics from 1995 to 2002. He is Editor of the Intl. Journal of Damage Mechanics (2008 JCR Impact Factor 1.971), and is an Editorial Board member of the Acta Mechanica. Prof. Ju has received the 1991 Presidential Young Investigator Award from the NSF and White House, 1991 Alfred Rheinstein Faculty Award from Princeton University, 1997 ASCE Walter Huber Civil Engineering Research Award, 1998 ASME Fellow Election, 2000 ACI-James-Instruments Award in NDE, 2006 ASCE Fellow Election, 2007 USACM Fellow Award, 2008 ACI Fellow Award, 2008-2009 Invited Chair Professorship from the University of Paris VI and ENS Cachan (France), 2008 Publication Award of Merit from the Structural Engineers Association of Illinois, and 2009 Chang-Jiang Scholar Chair Professor (China), etc. Prof. Ju�s publications have been highly cited by the ISI Web of Science. His research interests encompass structural engineering, structural mechanics, computational mechanics, damage & fracture mechanics, micromechanics & nanomechanics of composites, multiscale material modeling, finite elements, structural dynamics, biomechanics, geomechanics, NDE, and durability of concrete & cementitious composites.