The study of deformation and failure of solids, including brittle and ductile fracture, is well suited to methods of classical molecular dynamics (MD), which allows us to solve, on massively parallel computers, up to nearly a billion atoms in three dimensions, for ever more complex kinds of intermolecular interactions. A recent development in the field of massively parallel MD is the SPaSM code, which has been used to study ductile failure in copper, using Art Voter's EAM (embedded-atom method) potential for a sample comprising 35 million atoms. SPaSM is also capable of treating shock waves and interfacial friction, both of which are able to spawn large numbers of dislocations in crystals. These dislocations strongly interact and, along with defects such as cracks, require a large computational domain, in order to contain the cores and surrounding elastic fields. Moreover, thousands of vibrational periods are required for sound waves to propagate over these spatial domains, making this a challenge for computations as well as visualization of the 3D structures.
In addition to shock waves, fracture, and interfacial friction, we are able to study spallation and fragmentation, which are important failure processes in explosively driven systems.
People in T-12 working on this project include: