Bulletin of the American Physical Society
18th Biennial Intl. Conference of the APS Topical Group on Shock Compression of Condensed Matter held in conjunction with the 24th Biennial Intl. Conference of the Intl. Association for the Advancement of High Pressure Science and Technology (AIRAPT)
Volume 58, Number 7
Sunday–Friday, July 7–12, 2013; Seattle, Washington
Session H1: TM Computational Shock Compression of Single/poly Crystals |
Hide Abstracts |
Chair: Keith Gonthier, Louisiana State University Room: Grand Ballroom I |
Tuesday, July 9, 2013 9:15AM - 9:30AM |
H1.00001: Shock compression of Ta single crystals with dislocation sources Diego Tramontina, Ramon Ravelo, Eduardo Bringa We present non-equilibrium molecular dynamics (NEMD) simulations of shock wave compression of line Tantalum single crystals including pre-existing defects, which act as dislocation sources. We use the new embedded atom model (EAM) potential presented by Ravelo \textit{et al.} [Ravelo \textit{et al.}, SCCM2011 paper], developed for shock-wave simulations. We study the nucleation and evolution of dislocations and twins as a function of shock pressure and loading ramp time. We find a large dependence of the HEL (Hugoniot Elastic Limit) on strain rate. We compare the resulting dislocation densities and dislocation structures to existing experimental results on recovered samples. [Preview Abstract] |
Tuesday, July 9, 2013 9:30AM - 9:45AM |
H1.00002: Shock Compression of Beryllium Single Crystals: Time-Dependent, Anisotropic Elastic-Plastic Response J.M. Winey, Y.M. Gupta To gain insight into inelastic deformation mechanisms in shocked Be single crystals, wave propagation simulations were performed for crystals shocked along the c-axis, a-axis, and other crystal directions to peak stresses reaching 7 GPa. The simulations utilized a time-dependent, anisotropic material model that incorporated dislocation dynamics and deformation twinning based descriptions of inelastic deformation. The simulation results showed good qualitative agreement with the measured wave profiles [Pope and Johnson, J. Appl. Phys. 46, 720 (1975)], including features arising from wave mode coupling due to the highly anisotropic inelastic response of Be. The measured wave profiles can be understood in terms of dislocation slip along basal, prismatic, and pyramidal planes, together with deformation twinning. Our results provide insight into the complex nature of inelastic deformation in shocked Be, and are also expected to be valuable for understanding the anisotropic inelastic response of analogous hcp metals subjected to shock compression. Work supported by ARL and DOE/NNSA. [Preview Abstract] |
Tuesday, July 9, 2013 9:45AM - 10:15AM |
H1.00003: An Overview of Mesoscale Material Modeling with Eulerian Hydrocodes Invited Speaker: Karl Olney Eulerian hydrocodes were originally developed for simulating strong shocks in solids and fluids, but their ability to handle arbitrarily large deformations and the formation of new free surfaces makes them attractive for simulating the deformation and failure of materials at the mesoscopic scale. A summary of some of the numerical techniques that have been developed to address common issues for this class of problems is presented with the shock compression of powders used as a model problem. Achieving the correct packing density with the correct statistical distribution of particle sizes and shapes is, in itself, a challenging problem. However, since Eulerian codes permit multiple materials within each element, or cell, the material interfaces do not have to follow the mesh lines. The use of digital image processing to map the pixels of micrographs to the Eulerian mesh has proven to be a popular and useful means of creating accurate models of complex microstructures. Micro CT scans have been used to extend this approach to three dimensions for several classes of materials. The interaction between the particles is of considerable interest. During shock compression, individual particles may melt and form jets, and the voids between them collapse. Dynamic interface ordering has become a necessity, and many codes now have a suite of options for handling multi-material mechanics. True contact algorithms are now replacing multi-material approximations in some cases. At the mesoscale, material properties often vary spatially due to sub-scale effects. Using a large number of material species to represent the variations is usually unattractive. Directly specifying the properties point-wise as history variables has not proven successful because the limiters in the transport algorithms quickly smooth out the variations. Circumventing the limiter problem is shown to be relatively simple with the use of a reference configuration and the transport of the initial coordinates. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700