Search

In this paper, martensitic transformations in constrained Fe-Pd nanowires are studied using a mesoscopic model analyzed in detail numerically in our earlier papers. The dynamics of square-to-rectangular transformation is modeled by using the modified Ginzburg-Landau theory. The simulations are performed accounting for the thermal effects using the coupled equations of non-linear thermoelasticity. Up to date, these effects have typically been neglected in modeling microstructures at the scales of interest considered here. Nanowires of length 2000 nm and widths ranging from 200 nm to 50 nm are simulated to study the effect of size on the microstructure evolution. There exists a critical width below which the size effect is prominent. We present a series of numerical results demonstrating this phenomenon. We also have carried out the study of variations in values of bulk, shear, and Landau constants to understand the difference in evolved microstructure in the coupled and uncoupled physics.Copyright © 2010 by ASME

In the current paper, the hysteretic dynamics of ferroelectric materials under combined electro-mechanical loadings is investigated using a macroscopic differential model. The model is constructed on the basis of the Landau theory of the first order phase transformations. Hysteresis loops in the electric field and the butterfly-shaped behaviors in the electro-mechanical coupling are modeled as a consequence of polarizations and orientation switchings, together with nonlinear electro-mechanical coupling effects. The effects of bias stress on the orientation switchings are investigated numerically. Comparison of the model results with its experimental counterparts is presented, capability of the model is approved.Copyright © 2008 by ASME