The mechanical behavior of a Zircaloy-4 sheet as induced by a pulsed laser was studied with an accurately developed computational process that was validated with experiments. A modified Gaussian model of the heat source and the use of experimentally obtained thermal and mechanical properties of Zircaloy-4 in the computational process provided reliable simulation results of the phase transition and mechanical deformation of Zircaloy-4. A parametric study of the pulsed laser welding conditions of Zircaloy-4 was undertaken using the developed computational process. The analyzed parameters were the laser power, pulse duration, and pulse frequency. The simulation results revealed that the deformation was significantly dependent on the geometry of the molten zone and the heat-affected zone, which can be designed by the analyzed laser parameters.

Chemotaxis is one of the essential mechanisms responsible for variouscomplex biological processes. For a crawling cell, the interface between thecell and the substrate plays an important role in the chemotactic migration.This paper presents a three-dimensional dynamic model to investigate theeffect of the interface between a crawling cell and a substrate on itschemotaxis. The coupled mechanisms of chemotaxis, the surface energy of thecell, and the interface between the cell and the substrate are incorporatedinto a diffuse interface model. Simulations reveal rich dynamics of acrawling cell associated with the interfacial condition, and confirm thehigh possibility of adequate predictions.

A three dimensional electromigration model is presented to account for void evolution in small scale interconnects. The model provides better understanding of the evolution process by considering concurrent kinetics of creep flow and surface diffusion. The multiple kinetics and energetics are incorporated into a diffusive interface model. Simulations show that a shape stable in surface diffusion can become unstable in a creep dominated process, which leads to a quite different void morphology.

A thin polymer film subjected to an electrostatic field may lose stability at the polymer-air interface, leading to uniform self-organized pillars emerging out of the film surface. This paper presents a three dimensional dynamic model to account for the behavior. The coupled diffusion, viscous flow, and dielectric effect are incorporated into a phase field framework. Numerical simulations reveal rich dynamics of the pattern formation process and the substrate effect. The pillar size is insensitive to the film thickness, but the distance between pillars and the growth rate are significantly affected. The study suggests an approach to control structural formation in thin films with a designed electric field.

Experiments have shown that a thin polymer film subjected to an electrostatic field may lose stability at the polymer-air interface, leading to uniform self-organized pillars emerging out of the film surface. This paper presents a three dimensional dynamic model that accounts for the behavior. Attention is focused on the interplay of the thermodynamic forces and the kinetic processes. The coupled diffusion, viscous flow, and dielectric effect are incorporated into a phase field framework. The semi-implicit Fourier spectral method and the preconditioned biconjugate-gradient method are applied in the simulations for high efficiency and numerical stability. Numerical simulations reveal rich dynamics of the pattern formation process.

A thin two-component epilayer grown on a solid surface may separate into distinct phases. Sometimes the phases select sizes about 10 nm, and order into an array of stripes or disks. However, the pattern types are limited and the location of the features is not controlled. This paper develops a dynamic model to simulate guided self-assembly. In particular, we look at the effect of surface chemistry on the pattern formation process. The simulations suggest that diverse patterns may be produced by tuning the surface chemistry of a substrate. In addition, the self-assembled features may be anchored at specific locations.