Probabilistic Micromechanics-Based Damage Mechanics and Homogenization of Composite Materials for Predefined High Reliability and Life Expectancy
Professor J. Woody Ju, Ph.D., P.E.
Department of Civil and Environmental Engineering, UCLA
Los Angeles, CA 90095-1593
Time: 9:00 a.m. Friday, April 9, 2010
Presented to: Room 201, Department of Geotechnical Engineering,
In this work-in-progress, we combine the multi-level mechanics of advanced laminated fiber-reinforced conics, Bayesian updating, probabilistic technology, and finite elements to analyze and simulate the advanced laminated fiber-reinforced composite structures. In the proposed approach, the micro- and meso-mechanics of laminated fiber-reinforced composites and damage/fracture mechanicsmposite materials, micromechanical damage mechanics, fracture mecha will characterize the local component or constituent behaviors of individual elements (such as the matrix, fibers or inclusions, fiber/matrix interphases, and interlaminar boundaries) in composite materials. The Bayesian updating and classical statistical approach provides the capability for modeling uncertainties such as inherent uncertainty, model uncertainty, lack of statistical data, and measurement errors. Starting from the rigorous micro- and meso-mechanics of laminated fiber-reinforced composites at the ply level and subsequently at the multi-ply level, we investigate the matrix microcrack initiation and growth, the interfacial microcracks between the matrix and fibers, the fiber breaks, and the progressive delamination microcrack initiation and growth between two laminae. The stiffness degradation, reduced service life and deteriorated structural load-displacement responses of composite structures can be derived and simulated based on the mechanics and application of the multi-level homogenization technique.
Biographical Sketch: 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 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, 2009 Chang-Jiang Scholar Chair Professor, 2010 IACM Fellow Award, and 2010 Kwang-Hua Chair Professor (Tongji), 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, biomechanics, geomechanics, service life predictions, and durability of cementitious composites.