Friday, April 14th, 2017
3:00PM – 4:15PM
Boom or Bust? How Mechanical Properties Control Explosives
Los Alamos National Laboratory
Abstract: Weak impacts on energetic materials can give rise to violent reactions. The sequence of events from a mechanical insult to rapid, exothermic chemistry is inherently multiscale and spans the electronic structure through the mesoscale to continuum. The localization of deformation into hot spots, shear bands, and fracture is crucial. Hence, the microstructure and fundamental mechanical properties of energetic materials control many aspects of their safety and performance. Modeling high rate deformation in energetic materials has been an immense challenge owing to their anisotropy, complexity, and mechanical and chemical fragility. We recently developed physics-based, next generation thermomechanical models for the energetic material RDX that accurately predict its elastic and plastic anisotropy and phase behavior. The development and application of our thermomechanical models are closely integrated with shock compression experiments with in situ X-ray imaging and diffraction at the Advanced Photon Source and Linac Coherent Light Source. Recent work on integrated theory and experiments through which complex in situ data can be understood will be presented.
Bio: Marc Cawkwell is a materials scientist in the Theoretical Division of Los Alamos National Laboratory. He received an M.Eng. in Metallurgy and the Science of Materials from the University of Oxford in 2000, a Ph.D. in Materials Science and Engineering from the University of Pennsylvania in 2005, and the 2006 S. J. Stein Prize from the University of Pennsylvania. He joined Los Alamos National Laboratory in 2005 and was awarded a Director’s Postdoctoral Fellowship in 2006, becoming a staff member in 2008. His research focuses on the development and application of atomistic simulation methods to understanding the mechanical and chemical properties of organic materials under extreme conditions.