The purpose of this presentation is to provide an overview of the science-based materials modeling activities at Sandia National Laboratories, California. The main mission driver for the work is the development of predictive modeling and simulation capabilities leveraging high performance computing software and hardware. Presentation will highlight research accomplishments in several specific topics of current interest. Sandia/California has been engaged in the development of high performance computing based predictive modeling and simulation capabilities in support of the Science-Based Stockpile Stewardship Program of the U. S. Department of Energy. Of particular interest is the development of constitutive models that can efficiently and accurately predict post-failure material response and load-redistribution in systems and components. Fracture and failure are inherently multi-scale and our philosophy is to include required physics in our models at all appropriate scales. We approach the problems from the continuum point of view and intend to provide continuum models that include dominant subscale mechanisms. Moreover, numerical algorithms are needed to allow implementation of physical models in high performance computing codes such that large-scale modeling and simulation can be conducted. Other drivers of our effort include the emerging application of micro- and nano-systems and the increasing interest in biotechnology. In this presentation, our research in fracture and failure modeling, atomic-continuum coupling code development, microstructure-material properties relationships exploration, and general continuum theories advancement will be presented. Where appropriate, examples will be given to demonstrate the utility of the models.
We report our conclusions in support of the FY 2003 Science and Technology Milestone ST03-3.5. The goal of the milestone was to develop a research plan for expanding Sandia's capabilities in materials modeling and simulation. From inquiries and discussion with technical staff during FY 2003 we conclude that it is premature to formulate the envisioned coordinated research plan. The more appropriate goal is to develop a set of computational tools for making scale transitions and accumulate experience with applying these tools to real test cases so as to enable us to attack each new problem with higher confidence of success.
This report summarizes materials issues associated with advanced micromachines development at Sandia. The intent of this report is to provide a perspective on the scope of the issues and suggest future technical directions, with a focus on computational materials science. Materials issues in surface micromachining (SMM), Lithographic-Galvanoformung-Abformung (LIGA: lithography, electrodeposition, and molding), and meso-machining technologies were identified. Each individual issue was assessed in four categories: degree of basic understanding; amount of existing experimental data capability of existing models; and, based on the perspective of component developers, the importance of the issue to be resolved. Three broad requirements for micromachines emerged from this process. They are: (1) tribological behavior, including stiction, friction, wear, and the use of surface treatments to control these, (2) mechanical behavior at microscale, including elasticity, plasticity, and the effect of microstructural features on mechanical strength, and (3) degradation of tribological and mechanical properties in normal (including aging), abnormal and hostile environments. Resolving all the identified critical issues requires a significant cooperative and complementary effort between computational and experimental programs. The breadth of this work is greater than any single program is likely to support. This report should serve as a guide to plan micromachines development at Sandia.