MechE Colloquium: Multiscale Mechanics of Metal Plasticity
Event details
| Date | 16.11.2021 |
| Hour | 12:15 › 13:15 |
| Speaker | Prof. William A. Curtin, Laboratory for Multiscale Mechanics Modeling (LAMMM), Institute of Mechanical Engineering (IGM), School of Engineering (STI), EPFL |
| Location | Online |
| Category | Conferences - Seminars |
| Event Language | English |
Abstract:
Due to their many attractive properties, especially plastic flow and consequent good ductility, metals are used in applications spanning the domains of Mechanical, Aerospace, and Civil Engineering. The performance of metals depends, however, on material features across a wide range of scales, from macroscopic polycrystals down to the individual dislocations that carry the plastic displacements that generate macroscopic plasticity. Understanding and predicting the mechanical properties of metals is thus intrinsically a multiscale problem. After examining the general philosophy of multiscale modeling of mechanical properties, we examine (i) how metal plasticity is currently modeled at successively smaller scales, and (ii) why or when one must progress to lower scales that ultimately reach the domain of quantum mechanics. We then note that fundamental mechanics principles are used at each scale of investigation; continuum, mesoscale, atomistic, statistical and quantum mechanics tools are all “mechanics”. This puts mechanicians in excellent position to use the full range of tools to solve challenging technological problems. As one specific example, we outline a multiscale model for mechanistic understanding and quantitative prediction of dynamic strain aging phenomena that limit the macroscopic ductility of the technologically valuable Aluminum Al-5xxx alloys. The underlying dynamic phenomenon is atomistic, and requires quantum mechanics for quantitative accuracy. But the effects of the underlying mechanism must be carried up to the scale of dislocation motion and dislocation interaction, from which a full transient thermo-kinetic constitutive model can be derived. Such models must then be implemented in continuum finite element models to reveal how the atomistic phenomenon leads to reduced macroscopic ductility of standard test coupons over a range of temperatures and strain rates. This mechanistic insight across scales enables the computationally-guided search for new alloys that will have higher ductility which widens the domain of applicability of these desirable lightweight metals.
Bio:
Professor Curtin earned a 4 yr. ScB/ScM degree in Physics from Brown University in 1981 and a PhD in theoretical physics from Cornell University in 1986. He worked as staff researcher at British Petroleum until 1993 and then joined Virginia Tech as an Associate Professor in both Engineering Mechanics and Materials Science. In 1998 he returned to Brown as Full Professor of Engineering in the Solid Mechanics group, where he was appointed Elisha Benjamin Andrews Professor in 2006. He joined Ecole Polytechnique Federale de Lausanne as the Director of the Institute of Mechanical Engineering in 2011 and officially as Full Professor in 2012. His research successes include predictive theories of optical properties of nanoparticles, statistical mechanics of freezing, hydrogen storage in amorphous metals, strength and toughness of fiber composites, dynamic strain aging and ductility in lightweight Al and Mg metal alloys, solute strengthening of metal alloys including high entropy alloys, and hydrogen embrittlement of metals, along with innovative multiscale modeling methods to tackle many of these problems. Professor Curtin was a Guggenheim Fellow in 2005-06, was Editor-in-Chief of “Modeling and Simulation in Materials Science and Engineering” from 2006-2016, has published over 300 journal papers that have received over 20000 citations with an h-index of 78 (Google Scholar), and has been the Principal Investigator on well over $40M of funded research projects.
Due to their many attractive properties, especially plastic flow and consequent good ductility, metals are used in applications spanning the domains of Mechanical, Aerospace, and Civil Engineering. The performance of metals depends, however, on material features across a wide range of scales, from macroscopic polycrystals down to the individual dislocations that carry the plastic displacements that generate macroscopic plasticity. Understanding and predicting the mechanical properties of metals is thus intrinsically a multiscale problem. After examining the general philosophy of multiscale modeling of mechanical properties, we examine (i) how metal plasticity is currently modeled at successively smaller scales, and (ii) why or when one must progress to lower scales that ultimately reach the domain of quantum mechanics. We then note that fundamental mechanics principles are used at each scale of investigation; continuum, mesoscale, atomistic, statistical and quantum mechanics tools are all “mechanics”. This puts mechanicians in excellent position to use the full range of tools to solve challenging technological problems. As one specific example, we outline a multiscale model for mechanistic understanding and quantitative prediction of dynamic strain aging phenomena that limit the macroscopic ductility of the technologically valuable Aluminum Al-5xxx alloys. The underlying dynamic phenomenon is atomistic, and requires quantum mechanics for quantitative accuracy. But the effects of the underlying mechanism must be carried up to the scale of dislocation motion and dislocation interaction, from which a full transient thermo-kinetic constitutive model can be derived. Such models must then be implemented in continuum finite element models to reveal how the atomistic phenomenon leads to reduced macroscopic ductility of standard test coupons over a range of temperatures and strain rates. This mechanistic insight across scales enables the computationally-guided search for new alloys that will have higher ductility which widens the domain of applicability of these desirable lightweight metals.
Bio:
Professor Curtin earned a 4 yr. ScB/ScM degree in Physics from Brown University in 1981 and a PhD in theoretical physics from Cornell University in 1986. He worked as staff researcher at British Petroleum until 1993 and then joined Virginia Tech as an Associate Professor in both Engineering Mechanics and Materials Science. In 1998 he returned to Brown as Full Professor of Engineering in the Solid Mechanics group, where he was appointed Elisha Benjamin Andrews Professor in 2006. He joined Ecole Polytechnique Federale de Lausanne as the Director of the Institute of Mechanical Engineering in 2011 and officially as Full Professor in 2012. His research successes include predictive theories of optical properties of nanoparticles, statistical mechanics of freezing, hydrogen storage in amorphous metals, strength and toughness of fiber composites, dynamic strain aging and ductility in lightweight Al and Mg metal alloys, solute strengthening of metal alloys including high entropy alloys, and hydrogen embrittlement of metals, along with innovative multiscale modeling methods to tackle many of these problems. Professor Curtin was a Guggenheim Fellow in 2005-06, was Editor-in-Chief of “Modeling and Simulation in Materials Science and Engineering” from 2006-2016, has published over 300 journal papers that have received over 20000 citations with an h-index of 78 (Google Scholar), and has been the Principal Investigator on well over $40M of funded research projects.
Practical information
- General public
- Free