CAMCSEvents
Upcoming Seminars
October 2, 3 p.m., Latrobe 106 (Hughes Conference Room): Dennis Grady, ARA
"Fragmentation in the Shock and Ballistic Environment"
Dennis Grady Seminar Announcement Oct 2 2009
The catastrophic disruption of materials in the shock and ballistic environment
commonly plays a central role in both the successful application of armors systems and
the effective application of anti-armor systems. A theory of the dynamic fragmentation
of solids based on continuum energy principles has provided a basis for assessing
fragmentation in a wide range of applications over the past several decades. Applications
of the theory to the fragmentation of brittle solids including glass and ceramic have been
problematic, however. Recently, some of the physics issues governing length scales and
sized distributions in the dynamic fragmentation of brittle solids have come to light. The
earlier energy-based fragmentation theory is broadened to accommodate dynamic
fragmentation in brittle materials. The presentation will address some of the early history
of fragmentation, summarize past and more recent energy-based fragmentation theories,
and demonstrate application to fragmentation in the shock and ballistic environment.
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October 8, 11 a.m., Latrobe 106 (Hughes Conference Room): Avinash Dongare, North Carolina State University
"Atomic Scale Studies of Deformation and Failure Processes in Nanostructured Materials"
Avinash Dongare Seminar Announcement Oct 8 2009
Large-scale molecular dynamics (MD) simulations using the Embedded Atom Method (EAM)
potential are used to understand the deformation and failure behavior of nanocrystalline Cu/Al with very
small grain sizes (≤ 12 nm) under multi-axial loading conditions at high strain rates (strain rates ≥ 108 s-1).
Two aspects of deformation behavior of nanocrystalline metals will be discussed: tension-compression
strength asymmetry, and the plastic yield criteria at the macro scale. The micro-mechanisms related to
dynamic failure (nucleation, growth, and coalescence of voids) will also be discussed for conditions of
deformation that lead to the onset of spallation during shock loading. Atomic scale deformation studies of
ceramic particle reinforced metal-matrix nanocomposite materials are currently limited by the lack of
interatomic potentials to accurately model the complex interfaces. A new Angular-dependent Embedded
Atom Method (A-EAM) potential is developed that allows the combination of the EAM potentials for
metals with potentials for covalent interactions, thus giving the capabilities to model complex interfaces
(metal-covalent/ceramic) in ceramic particle reinforced metal matrix composites at the atomic scale. The
first results for the application of the A-EAM potential to model the deformation behavior of Al/Si
interfaces will be presented.
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Upcoming Collaborative Research Group Meetings
October 8, 2009, 8:30 a.m. to 11 a.m.