Eur. Phys. J. E (2012) 35: 40
https://doi.org/10.1140/epje/i2012-12040-y

Regular Article

Spontaneous formation of densely packed shear bands of rotating fragments

¹ CSC - IT centre for science, P.O. Box 405, FIN-02101, Esbo, Finland
² Department of Physics, University of Jyväskylä, P.O. Box 35, FIN-40014, Jyväskylä, Finland

^* e-mail: astrom@csc.fi

Received: 16 March 2012
Revised: 3 May 2012
Accepted: 4 May 2012
Published online: 29 May 2012

Abstract

Appearance of self-similar space-filling ball bearings has been suggested to provide the explanation for seismic gaps, shear weakness, and lack of detectable frictional heat formation in mature tectonic faults (shear zones). As the material in a shear zone fractures and grinds, it could be thought to eventually form a conformation that allows fragments to largely roll against each other without much sliding. This type of space-filling “ball bearing” can be constructed artificially, but so far how such delicate structures may appear spontaneously has remained unexplained. It is demonstrated here that first-principles simulations of granular packing with fragmenting grains indeed display spontaneous formation of shear bands with fragment conformations very similar to those of densely packed ball bearings.