Abstract

The Interrelated aspects of thermo-mechanical behavior with a specific focus on microstructural characteristics and defects, such as partial and total dislocations densities and grain-boundaries (GBs) that span the nano to the micro, and how these characteristics affect failure modes, such as fracture nucleation in crystalline materials, will be presented. Recently developed methodologies have been used for a detailed analysis of fracture nucleation and the accurate characterization of intergranular and transgranular crack growth. Criteria for dislocation-density mechanisms and immobilization are directly related to interactions with GB ledges and propagating cracks in polycrystalline aggregates. The effects of interfaces, such as GB blockage, dislocation-density motion, and pileups on fracture nucleation will be discussed. The predictions are validated with micropillar compression experiments and provide further understanding how defects, such as partial and total dislocation-densities, affect failure nucleation and intergranular and transgranular fracture at different physical scales.

Brief Biography: 

Mohammed A. Zikry is the Zan Prevost Smith Professor at North Carolina State University in the Department of Mechanical and Aerospace Engineering. His research expertise is in the general areas of multiscale modeling, mechanics of materials, fracture and defect mechanics, computational mechanics, and crystalline plasticity. He is developing predictive computational, and experimental methodologies that can be used at physical scales ranging from the nano to the macro levels to understand how material behavior can be harnessed for new and significantly improved materials, devices, and structures for systems comprised of metallic alloys, intermetallics, ceramics, composites, biomaterials, and shape memory polymers. He has received the Jefferson Science Fellowship (advisor to the Secretary of State, U.S. State Department), the ASME Thurston Lecture Society Award from ASME. He is a Fellow of the American Association for the Advancement of Science (AAAS), the Society of Engineering Science (SES) and the American Society of Mechanical Engineering (ASME) and was the editor in Chief of the ASME Journal of Engineering Materials and Technology, is an Editor for Mechanics of Materials, and an Associate Editor for Scientific Reports, Metals, and Frontiers in Materials. He received his Ph.D. from the University of California, San Diego, his M.S. from the Johns Hopkins University, and his B.S. from the University of Kansas.