MSE/ME Special Seminar on Computational Materials Science and Materials Modeling - Peter Chung
Thursday, February 28, 2013
Rm. 1105, Jeong H. Kim Eng. Bldg. (Pepco Room)
301 405 4799
Multiscale Materials Modeling of RDX and Crystal Defects
Peter W. Chung, PhD
Computational Sciences Division
Computational & Information Sciences Directorate
US Army Research Laboratory
Many compelling open scientific problems remain at the intersection of mechanics, materials, and computing. In the opinions of many, there is a great likelihood that their solutions will enable revolutions in technologies that, for instance, will give the Army monumental improvements in safety, functionality, and cost efficiency. In this talk, I will overview recent research results broadly aligned under two themes. The first is RDX, an energetic material whose crystalline structure is comprised of molecules. Using a range of multiscale techniques, many of which have been developed in the Army, new insights have been gained about mechanical and thermophysical mechanisms in RDX. Specifically, plasticity, heat capacity, and thermal diffusivity are investigated without recourse to engineering empirical parameters. This enables a clearer understanding of the effect that molecules have on macroscopically observable properties of an otherwise crystalline material.
The second theme targets the increasing need for mesoscale modeling to investigate emergent challenges in energy materials. Prompted by the Armys need for improved dielectric performance, we have developed a new capability to study dislocation forests in thin film device materials. A comprehensive multiscale approach will be shown fundamentally enabled by a new simulator that can treat dislocation forests in arbitrarily shaped domains of any general crystalline structure. Recent computed results will be shown for, among others, surface-mitigated Frank Read sources, binary dislocation junction strength of Magnesium and Beryllium, anisotropic glide mechanisms of edge dislocations in Gallium Nitride, and a forest demonstration in a three-dimensional bending microcantilever device.