A Multiscale Characterization and Analysis Methodology for Ductile Fracture in Heterogeneous Metalli

Speaker: Dr. Somnath Ghosh,Department of Mechanical Engineering, Ohio State UniversityHeterogeneous metallic materials e.g. cast aluminum alloys or metal matrix composites are widely used in automotive, aerospace, nuclear and other engineering systems. The presence of precipitates and particulates in the microstructure often affect their failure properties like fracture toughness or ductility in an adverse manner. Important micromechanical damage modes that are responsible for deterring the overall properties include particulate fragmentation, debonding at interfaces and ductile matrix failure due to void initiation, growth and coalescence, culminating in local ductile failure. The complex interaction between competing damage modes in the presence of multiple phases makes failure and ductility prediction for these materials quite challenging. While phenomenological and straightforward micromechanics models have predicted stress-strain behavior and strength of multi-phase materials with reasonable accuracy, their competence in predicting ductility and strain-to-failure, which depends on the extreme values of distribution, is far from mature. To address the needs of a robust methodology for ductility, the work will discuss a comprehensive multi-scale characterization based domain decomposition method followed by a multi-scale model for deformation and ductile failure. Adaptive multi-scale models are developed for quantitative predictions at critical length scales, establishing functional links between microstructure and response, and following the path of failure from initiation to rupture. The work is divided into three modules. (i) Multi-scale morphology based domain partitioning to develop a pre-processor for multiscale modeling, (ii) Enriched Voronoi Cell FEM for particle and matrix cracking leading to ductile fracture and (iii) Macroscopic homogenization continuum damage model for ductile fracture. Finally a robust framework for two-way multi-scale analysis module is the coupling of different with different inter-scale transfer operators and interfaces is developed.Bio-SketchDr. Somnath Ghosh is the John B. Nordholt Professor in the Department of Mechanical Engineering at the Ohio State University. He received his M.S. in Theoretical and Applied Mechanics from Cornell University and PhD from the University of Michigan. His research interests include multiple scale modeling in spatial and temporal domains, failure and fatigue modeling in heterogeneous materials and structures, Computational nanotechnology, etc. He is a fellow of American Association for the Advancement of Science (2008), US Association of Computational Mechanics (2007), ASM International (2006) and ASME (2002). In 2007, the Ohio State University awarded him the University Distinguished Scholar award. He got the National Science Foundation Young Investigator award of NSF in 1994. He was an elected member of the executive council of the US Association of Computational Mechanics (USACM) from 2002-2006 and is the Chair of USACM’s Materials Modeling committee. The US Association of Computational Mechanics has chosen him to be the organizer of the 10th US National Congress of Computational Mechanics in 2009.

Location: Kaprielian Hall (KAP) - 209

Audiences: Everyone Is Invited

Contact: Evangeline Reyes