This project will address the dynamics and properties of disordered systems under stress using simulations and the energy landscape framework. Many important materials are disordered. Liquids and glasses are disordered on a molecular level. Soft-matter systems, such as colloids and foams, are disordered on a larger length scale. The dynamics and properties of disordered materials are universal in many ways, because the effects of many local optima for particle packing dominate the dynamics.
Disordered materials are often subjected to stresses. Stress can cause the material to deform, to fracture, or to flow, depending on the nature of the stress and the conditions of the material. Additionally, nanoscale structure can act effectively as a stress on the system, and alter the dynamics and properties relative to the bulk. The goal of this project is to elucidate the dynamics of disordered materials under stress, and how these dynamics determine the properties of materials under stress.
The novelty of this project is the application of the energy landscape formalism to disordered systems under stress. The energy landscape formalism has emerged as a powerful framework to address the dynamics of disordered systems. The PI's recent work has shown that strain leads to distortions of the energy landscape, including the disappearance of energy minima. The consequences of these landscape distortions depend on the timescale over which these landscape distortions occur relative to the timescale for thermally activated relaxations. If these timescales are comparable, the landscape distortions significantly alter the system dynamics, which in turn significantly alters the system properties. This timescale regime is relevant for non-Newtonian flow and fracture processes.
The project will consist of non-equilibrium molecular dynamics simulations along with calculations that map out the potential energy landscape. The specific phenomena that will be addressed include (a) relationships between the dynamics of driven and thermal systems; (b) dynamical heterogeneities in driven systems; (c) avalanche events in stressed systems; (d) shear-induced alignment and its effect on properties in anisotropic systems; (e) effects of stress on aging; (f) fracture propagation; and (g) effects of nanoscale confinement on dynamics.
A broader impact of the research is an improved understanding of non-Newtonian flow, fracture, and nanostructured materials. Another broader impact is the training of new scientists, particularly the mentoring of undergraduate student researchers. %%% This project will address the dynamics and properties of disordered systems under stress using simulations and the energy landscape framework. Many important materials are disordered. Liquids and glasses are disordered on a molecular level. Soft-matter systems, such as colloids and foams, are disordered on a larger length scale. The dynamics and properties of disordered materials are universal in many ways, because the effects of many local optima for particle packing dominate the dynamics.
A broader impact of the research is an improved understanding of non-Newtonian flow, fracture, and nanostructured materials. Another broader impact is the training of new scientists, particularly the mentoring of undergraduate student researchers. ***
