Rearrangements in Jamming

In collaboration with Johannes Simon, Zorana Zeravcic, Simon Dagois-Bohy, Brian P. Tighe and Martin van Hecke

In the last decade, computer simulations have been used to gain insight in the behaviour of granular matter. This has allowed a description of the behaviour for small deformations. In this project, we are working on what happens beyond small deformations.

When a packing is deformed further, the microscopic contacts between particles change. The response to a small deformation is fully given by these contacts, so a change in the contacts means a change in the linear response.

In addition, we are interested in macroscopic rearrangements: the behaviour one would classify as a rearrangement in an experiment. This is connected to large particle movements, and to events called ‘T1-events’, where one pair of neighbouring particles becomes next-neighbours, which allows two next-neighbours to become neighbours.

We currently focus on the making and breaking of contacts between particles, as this is a measure that is easily accessible from simulations. We have seen that the shear strain at which such a contact change happens can be predicted from the macroscopic parameters: the number of particles and the pressure. In addition, we have seen the probability of creating a new contacts versus breaking an existing contact can also be determined by these two parameters.