A discrete element study of settlement in vibrated granular layers: role   of contact loss and acceleration
  This paper deals with the vibration of granular materials due to cyclic external excitation. It highlights the effect of the acceleration on the settlement speed and proves the existence of a relationship between settlement and loss of contacts in partially confined granular materials under vibration. The numerical simulations are carried out using the Molecular Dynamics method, where the discrete elements consist of polygonal grains. The data analyses are conducted based on multivariate autoregressive models to describe the settlement and permanent contacts number with respect to the number of loading cycles. 
Ali Karrech (LAMI), Denis Duhamel (LAMI), Guy Bonnet, Fran\c{c}ois   Chevoir (LAMI), Jean-Noel Roux (LAMI), Jean Canou (LAMI...