Blog posts
Simulating Fullerene Ball Bearings of Ultra-low Friction
We report the direct molecular dynamics simulations for molecular ball bearings composed of fullerene molecules (C60 and C20) and multi-walled carbon nanotubes. The comparison of friction levels indicates that fullerene ball bearings have extremely low friction (with minimal frictional forces of 5.283×10-7 nN/atom and 6.768×10-7 nN/atom for C60 and C20 bearings) and energy dissipation (lowest dissipation per cycle of 0.013 meV/atom and 0.016 meV/atom for C60 and C20 bearings). A single fullerene inside the ball bearings exhibits various motion statuses of mixed translation and rotation. The influences of the shaft's distortion on the long-ranged potential energy and normal force are discussed. The phonic dissipation mechanism leads to a non-monotonic function between the friction and the load rate for the molecular bearings.
Del.icio.us
Del.icio.us is a social bookmarking web service. One might say, why do I need del.icio.us if I have bookmarking capabilities built right into my browser? Well, here are some reasons:
- del.icio.us uses a non-hierarchical categorization system, that is, instead of organizing your bookmarks in folders, you assign tags to them.
Micromechanical Exfoliation and Graphene: 1999 papers and brief discussion of them
The discovery of a new material type, graphene and extremely thin platelets of graphite, was discussed in several articles from my research group published in 1999:
Lu XK, Huang H, Nemchuk N, and Ruoff RS, Patterning of highly oriented pyrolytic graphite by oxygen plasma etching, APPLIED PHYSICS LETTERS, 75, 193-195 (1999).
A good beginning of 2007
In the very beginning of 2007 I have four papers published or accepted (one is independent research and others are collaborated). All of them are the work done in my doctoral period. The topic is focusing on the enhancement of creep resistance of polymers by incorporating of nanofillers including particles and CNTs.
an interesting puzzle: multiscale mechanics
an interesting puzzle for fun:
Lame’s classical solution for an elastic 2D plate, with a hole of radius a and uniform tensile stress applied at the far field, gives a stress concentration factor (SCF) of two at the edge of the hole. This SCF=2 is independent of the hole radius.
Consider what happened to this concentration factor if the radius a approaches infinitely small. The SCF is independent of a, so it remains equal to two even when the hole disappears.
Three-dimensional anisotropic elasticity - an extended Stroh formalism
Tom Ting and I have recently developed a method of extending Stroh's anisotropic formalism to problems in three dimensions. The unproofed paper can be accessed at http://www-personal.umich.edu/~jbarber/Stroh.pdf .
Quasi-continuum orbital-free density-functional theory : A route to multi-million atom electronic structure (DFT) calculation
I would like to share the research work I have been pursuing over the past four years. I believe, through this forum, I will be able to reach researchers with various backgrounds and expertise. Suggestions and comments from members will be very useful. I am also attaching links to preprints of manuscripts describing this work. Please follow these links:
http://www-personal.umich.edu/~vikramg/academic/Preprints/QC-OFDFT.pdf