Predicting Defects in Soft Sphere Packings near Jamming Using the Force Network Ensemble

Amorphous systems of soft particles above jamming have more contacts than are needed to achieve mechanical equilibrium. The force network of a granular system with a fixed contact network is thus underdetermined and can be characterized as a random instantiation within the space of the force network ensemble. In this Letter, we show that defect contacts that are not necessary for stability of the system can be uniquely identified by examining the boundaries of this space of allowed force networks. We further show that, for simulations in the near jamming limit, this identification is nearly always correct and that defect contacts are broken under decompression of the system.

Automated summary

The study reveals that excess contacts in amorphous systems of soft particles can prevent mechanical equilibrium, and defect contacts can be uniquely identified by examining the boundaries of the force network ensemble. In simulations near the jamming limit, this identification is almost always correct, and defect contacts are broken when the system is decompressed.