%0 Journal Article
%T Jammed frictional tetrahedra are hyperstatic
%A Max Neudecker
%A Stephan Ulrich
%A Stephan Herminghaus
%A Matthias Schr£¿ter
%J Physics
%D 2012
%I arXiv
%R 10.1103/PhysRevLett.111.028001
%X We prepare packings of frictional tetrahedra with volume fractions {\phi} ranging from 0.469 to 0.622 using three different experimental protocols under isobaric conditions. Analysis via X-ray micro-tomography reveals that the contact number Z grows with {\phi}, but does depend on the preparation protocol. While there exist four different types of contacts in tetrahedra packings, our analysis shows that the edge-to-face contacts contribute about 50% of the total increase in Z. The number of constraints per particle C increases also with {\phi} and even the loosest packings are strongly hyperstatic i.e. mechanically over-determined with C approximately twice the degrees of freedom each particle possesses.
%U http://arxiv.org/abs/1202.6272v4