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Full-Text Articles in Nanoscience and Nanotechnology
Variable-Cell Method For Stress-Controlled Jamming Of Athermal, Frictionless Grains, Kyle C. Smith, Ishan Srivastava, Timothy Fisher, Meheboob Alam
Variable-Cell Method For Stress-Controlled Jamming Of Athermal, Frictionless Grains, Kyle C. Smith, Ishan Srivastava, Timothy Fisher, Meheboob Alam
Birck and NCN Publications
A method is introduced to simulate jamming of polyhedral grains under controlled stress that incorporates global degrees of freedom through the metric tensor of a periodic cell containing grains. Jamming under hydrostatic (isotropic) stress and athermal conditions leads to a precise definition of the ideal jamming point at zero shear stress. The structures of tetrahedra jammed hydrostatically exhibit less translational order and lower jamming-point density than previously described maximally random jammed hard tetrahedra. Under the same conditions, cubes jam with negligible nematic order. Grains with octahedral symmetry having s > 0.5 (where s interpolates from octahedra [s = 0] to cubes …
Role Of Nanostructure On Reaction And Transport In Ni/Al Intermolecular Reactive Composites, Mathew J. Cherukara, Karthik Guda Vishnu, Alejandro Strachan
Role Of Nanostructure On Reaction And Transport In Ni/Al Intermolecular Reactive Composites, Mathew J. Cherukara, Karthik Guda Vishnu, Alejandro Strachan
Birck and NCN Publications
We use molecular dynamics to characterize the exothermic chemistry of Ni/Al nanolaminates for various temperatures, periodic lengths, and in the presence of extended defects. We show that the reaction is mass diffusion controlled for bulk nanolaminates, with the overall reaction time scaling with the square of the mean transport distance. The presence of voids or free surfaces not only leads to a significant decrease in reaction time (by as much as a factor of 5), but fundamentally changes the nature of the reaction. Free surfaces and voids running across several periods provide a mechanism for ballistic mass transport and change …