Description:

Monday, April 30, 2018

3:00pm - 4:00pm

Issues and Challenges in Chemistry Driven Engineering Constitutive Models for Heterogeneous Materials: A Multiscale Approach

Abstract

The mechanical and constitutive response of materials like cement, and bio materials like fish scale is very complex due to heterogeneities that are inherently present in the nano and microstructures. The elastic properties are no longer isotropic, but depend on the functional distributions of the various structures in the materials which lead to anisotropy. The intrinsic constitutive behaviors are driven by the chemical composition and the molecular, micro, and meso structures. The fish scale is a layered functional material with a ganoine layer that is mostly hydroxyapatite followed by the functionally graded bone layer with more and more collagen fibers. This bilayer hydroxyapatite and collagen-based bio-laminate have chemistry driven complex nano/micro structures. The modeling methodology included modeling at nano level using molecular dynamics simulations that incorporate the nanoscale features to determine the mechanical properties. A micro/meso scale analyses were based on RVE or AEH (Asymptotic Expansion Homogenization) computational approaches using three dimensional finite element codes. The results from these various advanced computational methods can be integrated to build phenomenological engineering constitutive relationships to describe the global response of heterogeneous systems.

Biography

Dr. Arunachalam M. “Raj” Rajendran is the Chairman and Professor for the Department of Mechanical Engineering at the University of Mississippi (UM) in Oxford, MS. Dr. Rajendran served the U.S. Army Research Laboratory (ARL) during 1992-2008. Prior to serving ARL, he conducted basic and applied Research at the University of Dayton Research Institute, Dayton, Ohio in1981-1992. His research work has been recognized through numerous career and scientific awards. He is elected Fellow of ASME and SES, Distinguished Fellow of ICCES, and Emeritus Fellow of Army Research Laboratory. Dr. Rajendran has received the University of Mississippi - School of Engineering’s Outstanding Teacher Award in 2011, Outstanding Faculty Award in 2016, and Excellence in Graduate Teaching and Mentoring in 2018. He obtained his PhD from the University of Washington, Seattle, WA in 1981.