Center for Simulation of Dynamic Response of Materials

Solid Dynamics

Engineering models of material behavior are often phenomenological in nature and thus mired in empiricism and uncertainty. Worse yet, the phenomenological approach, consisting of fashioning direct fits to experimental data, does not offer a rational avenue for reducing the uncertainty and enhancing the fidelity of the models it engenders. Consequently, engineering models tend to break down when applied outside the confines of their empirical basis and, therefore, lack true predictive power. The reaction to this shortcoming is often the consideration of new sets of empirical data. However, each fit to a new data set adds layers of complexity and uncertainty to the model. In addition, the parameters of the models are often devoid of direct physical meaning and, in consequence, are not amenable to determination from first-principles calculations.

Multiscale modeling offers a rational and systematic avenue for building hierarchical models of complex material behavior with a minimum of empiricism and uncertainty. Multiscale modeling is a divide-and-conquer modeling paradigm. First, the entire range of material behaviors is divided into a hierarchy of length scales. Second, the relevant unit processes are identified at each length scale. The unit processes at one scale represent averages of unit processes operating at the immediately lower length scale. This relation introduces a partial ordering of processes. In addition, the unit processes should operate roughly independently: two processes that are tightly coupled should be considered as a single unit process. For systems where these relations are well defined, the modeling effort reduces to the analysis of each unit mechanism in turn and the computation of averages, eventually leading to a full description of the macroscopic behavior of the material. This is an inductive process that must ultimately be founded upon fundamental theories such as quantum mechanics.

The Solid Dynamics effort is structured in accordance to a multiscale modeling paradigm, with activities ranging in scale from the quantum-mechanical realm to full-scale engineering systems and components. The proposed scope and main target areas of the project are:

1. Shock-induced dynamic fracture, spallation and fragmentation in metals, including model systems such as Al
   and Li, and other materials.
2. The dynamics of shocked BCC metals, with particular focus on materials such as Fe exhibiting coupled martensitic transformations and plasticity.

Additional overarching goals of the solid dynamics project are:

1. The development of scalable solution procedures enabling high-fidelity integrated simulations of multicomponent engineering systems within the VTF (in collaboration with the Compressible Turbulence and Combustion (CTC) and CS groups).
2. The validation and verification of all models of material behavior and numerical algorithms developed under
   the project.

All material on these pages is Copyright © 2003 ASC/CSDRM.
Please report problems with this page to: webmaster@cacr.caltech.edu