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Special AMO/QO Physics Seminar


"Constitutive Phase Field Modeling of Shape Memory Alloys using the Notion of Configurational Forces and Order parameter"


Mr. Babatunde O. Agboola
Texas A&M University

ABSTRACT 

Recently, based on earlier works which dates back to the likes of Gibbs and Eshelby, Gurtin (2000) reported that the notion of configurational, accretive or materials forces should be considered as been basic object consistent with their own force balance in the continuum modeling of evolving surfaces, defects and interfaces. In this theory, it is believed that fundamental physical laws involving energy should account for working (expenditure of power) associated with each operative kinematic process. To each independent kinematic descriptor, a force system is assigned and to each density of force a work conjugate generalized velocity. Extension of this theory to continuum modeling of dynamic of solid-solid phase transition, which encompasses the classical phase field kinetic equations (i.e. Ginzburg-Landau and Cahn-Hilliard Equation) is applied in this work. This paradigm is being employed to constitutively develop (i) a thermomechanical and (ii) elasticity-diffusion coupled models with application to shape memory alloys. In addition to the new configurational force balance, appropriate fundamental laws of continuum physics are employed. Thermomechanical macroscopic response of martensitic transformation in shape memory alloys (SMA) is modeled through the nucleation of a second phase and propagation of their interface, boundaries or transformation front within a parent phase. Consistency with the second law of thermodynamics is ensured though the Coleman-Noll entropy principle. The elasticity-diffusion coupled model is intended to predict diffusion controlled precipitation in SMA- which have been reported to affect the transformation temperature. Simulation of experimentally observed stress-strain response for pseudoelastic NiTi SMA as well as transformation induced pseudo-viscoelastic behavior during forward transformation of SMA will be discussed as initial verification and validation of the thermomechanical model and by extension give credibility to this theory. The 3-D elasticity-diffusion model will be briefly discussed


Tuesday, October 14, 2014
IQSE 578, 1:00 PM
Mitchell Physics Building


Institute for Quantum Science and Engineering
Texas A&M University

(Pizza, salad, and soda to be served 30 minutes prior start time)

Host: Dr. Scully