NANOMEC-06

MATERIALS SCIENCE AND MATERIALS
MECHANICS AT THE NANOSCALE

MODELING, EXPERIMENTAL MECHANICS & APPLICATION

INTRODUCTION

Modern theories of materials are highly effective when describing macro-scale material properties. However, new developments in material science and technology have concentrated on smaller scales. For example, work in the thin films and nanotubes, particularly in electronics, has required new theories, which are still  being developed. Recent years have seen the emergence of what is now called Nano-Science and Technology, where length scales are sub-micron and smaller - down to the nanometer dimension. At these scales, it is found that many aspects of traditional solid-state physics do not apply.
To meet the material challenges in the emerging field of micro- and nanoscience, and to support the development and application of technology at these scales, it is necessary to further develop and standardize the procedures used to design, fabricate and assess these materials and such properties as those that describe the behavior and strength of micro- and nano-devices.  No comprehensive theory is available to describe material properties and interactions at these scales. In a mechanical system for which structures can involve as few as a dozen atoms, the conventional statistically based concepts for mechanical properties such as friction and viscosity tend to fail, or at the very least become difficult to apply. A number of experimental observations on the meso-scale or micro-scale, such as the occurrence and dynamics of vortex-like structures, remain unexplained. The application of traditional theories is insufficient to explain why the mechanical properties of metallic micro-devices can be drastically altered by nano-scale surface treatment. Dislocation theory is capable of describing deformation and fracture, but at the nano-scale there is the need of further developments to produce a more comprehensive theory at this level. For properties such as Young's modulus, it is already established that macro-scale values do not apply at the nano-scale. Molecular dynamics is capable of describing phenomena at the nano-scale, but the description uses parameters determined under conditions of thermal equilibrium. But events such as the fracture of material are thermally non-equilibrium processes, so the validity of using parameters determined at equilibrium conditions is at least questionable. To enable the community to address these challenges, theoretical breakthroughs are needed.
Material phenomena are presenting challenges as we move to the nano-scale. If we are to have adequate models, it is necessary to move to theories that do not use a scale factor or for which equilibrium assumptions are not a pre-requisite. One approach to this challenge is to consider the dynamics of processes at a fundamental physics level. For example, universal physical principles such as the Lagrangian formalism or symmetry can be used to formulate descriptions of dynamic processes without the use of statistical parameters or phenomenology that involves a scale factor. Another approach could use numerical simulation techniques for processes that do not rely on analytical models, such as the Monte Carlo or cellular automata methods. There are equal challenges in developing experimental methods to provide observations of events at the nano level to constrain theoretical models. To meet these challenges, high spatial and/or temporal resolution methods will be needed for application at the sub-micron and down towards the nano-scale.
The purpose of this symposium is to focus on the underlying physics of the non-equilibrium phenomena encountered in dynamic processes at the nano and near-nano scales. It is of fundamental importance to review the state of the art of nanoscience applications in different fields and the progress that has been achieved. The meeting aims to bring together scientists and engineers from various fields of study, to better define the challenges and to review the current state of science and technology at the nano level. In summary, the goal of the meeting is to stimulate the community by identifying both the challenges faced and potentially fruitful approaches towards solutions. The meeting also attempts to bring together both the fundamental and applied science communities to consider the theoretical models, measurement challenges and applications. Therefore, the schedule of meeting is organized in plenary sessions for most of its duration. Due to time constraints, applications will be handled in two parallel sections.