title: Jammed frictional tetrahedra are hyperstatic.
abstract: We prepare packings of frictional tetrahedra with volume fractions ϕ ranging from 0.469 to 0.622 using three different experimental protocols under isobaric conditions. Analysis via x-ray microtomography reveals that the contact number Z grows with ϕ, 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 ϕ and even the loosest packings are strongly hyperstatic, i.e., mechanically overdetermined with C approximately twice the degrees of freedom each particle possesses.
authors.affiliation: Max Planck Institute for Dynamics and Self-Organization, 37077 Goettingen, Germany. max.neudecker@ds.mpg.de
authors.forename: Max
authors.initials: M
authors.lastname: Neudecker
authors.forename: Stephan
authors.initials: S
authors.lastname: Ulrich
authors.forename: Stephan
authors.initials: S
authors.lastname: Herminghaus
authors.forename: Matthias
authors.initials: M
authors.lastname: Schröter