Toughness Of Ni/Al2O3 Interfaces As Dependent On Micron-Scale Plasticity And Atomistic-Scale Separation

Ceramic/metal interfaces were studied that fail by atomistic separation accompanied by plastic dissipation in the metal. The macroscopic toughness of the specific Ni alloy/Al2O3 interface considered is typically on the order of ten times the atomistic work of separation in mode I and even higher if combinations of mode I and mode II act on the interface. Inputs to the computational model of interface toughness are: (i) strain gradient plasticity applied to the Ni alloy with a length parameter determined by an indentation test, and (ii) a potential characterizing mixed mode separation of the interface fit to atomistic results. The roles of the several length parameters in the strain gradient plasticity are determined for indentation and crack growth. One of the parameters is shown to be of dominant importance, thus establishing that indentation can be used to measure the relevant length parameter. Recent results for separation of Ni/Al2O3 interfaces computed by atomistic methods are reviewed, including a set of results computed for mixed mode separation. An approximate potential fit to these results is characterized by the work of separation, the peak separation stress for normal separation and the traction-displacement relation in pure shearing of the interface. With these inputs, the model for steady-state crack growth is used to compute the toughness of the interface under mode I and under the full range of mode mix. The effect of interface strength and the work of separation on macroscopic toughness is computed. Fundamental implications for plasticity-enhanced toughness emerge.

Large Scale Numerical Simulations For Multi-Phase Fluid Dynamics With Moving Interfaces

This short communication presents our recent studies to implement numerical simulations for multi-phase flows on top-ranked supercomputer systems with distributed memory architecture. The numerical model is designed so as to make full use of the capacity of the hardware. Satisfactory scalability in terms of both the parallel speed-up rate and the size of the problem has been obtained on two high rank systems with massively parallel processors, the Earth Simulator (Earth simulator research center, Yokohama Kanagawa, Japan) and the TSUBAME (Tokyo Institute of Technology, Tokyo, Japan) supercomputers.

Estudio y desarrollo de un asistente (wizard) para la generación de interfaces de usuario abstractas en entornos ubicuos.

En el presente proyecto se pretende desarrollar una herramienta, que tiene como objetivo asistir a diseñadores de servicios ubicuos en el proceso de generación de interfaces abstractas de usuario para entornos ubicuos. Esta herramienta facilita la tarea a los diseñadores eliminando la necesidad de que conozcan la sintaxis UIML de descripción de interfaces de usuario, ya que el documento que guarda dicha descripción se genera automáticamente tras la utilización del asistente. Este asistente permite también, enriquecer dichas descripciones ofreciendo la posibilidad de asociar a los diferentes objetos abstractos de interacción que componen la interfaz, distintos tipos de recursos multimedia. El documento UIML generado se integra en el sistema Egoki, proporcionándole la entrada necesaria para generar interfaces de usuario accesibles y adaptadas a las necesidades de las personas que desean utilizar los servicios ubicuos.