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Seminar Abstracts

Avadh Saxena

"Theoretical Division & Center for Nonlinear Studies, Los Alamos National Lab"

Abstract

We summarize recent progress in modeling both the static and dynamic microstructure evolution as well as stress-strain constitutive response in martensitic phase transformations and shape memory alloys using simulations based on a Ginzburg-Landau free energy approach in terms of strain tensor components. We explicitly incorporate the elastic compatibility constraints in the formalism which lead to anisotropic long-range forces between order parameter strain(s). We compare this approach with a displacement based approach and elucidate the relative advantages of the two approaches. Finally, we extend this mesoscopic approach to model multiferroic materials with multiple coupled order parameters (e.g. strain, magnetization, polarization, shuffle modes) including the direct magnetoelectric coupling between polarization and magnetization. We discuss the role of long-range elastic, polar and magnetic dipole interactions in determining the physical properties. We summarize recent progress in modeling both the static and dynamic microstructure evolution as well as stress-strain constitutive response in martensitic phase transformations and shape memory alloys using simulations based on a Ginzburg-Landau free energy approach in terms of strain tensor components. We explicitly incorporate the elastic compatibility constraints in the formalism which lead to anisotropic long-range forces between order parameter strain(s). We compare this approach with a displacement based approach and elucidate the relative advantages of the two approaches. Finally, we extend this mesoscopic approach to model multiferroic materials with multiple coupled order parameters (e.g. strain, magnetization, polarization, shuffle modes) including the direct magnetoelectric coupling between polarization and magnetization. We discuss the role of long-range elastic, polar and magnetic dipole interactions in determining the physical properties.

FRIDAY, December 15, 2006
Time: 1:30 P.M.
Location: PPB 300