Master curves for the stress tensor invariants in stationary states of static granular beds. Implications for the thermodynamic phase space

• Autores: Pugnaloni, Luis Ariel; Damas, Jose; Zuriguel, Iker; Maza, Diego
• Año de publicación: 2011
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: GRANULAR PACKINGS
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

We prepare static granular beds under gravity in different stationary states by tapping the system with pulsed excitations of controlled amplitude and duration. The macroscopic state-defined by the ensemble of static configurations explored by the system tap after tap-for a given tap intensity and duration is studied in terms of volume, V, and force moment tensor, Sigma. In a previous paper [Pugnaloni et al., Phys. Rev. E 82, 050301(R) (2010)], we reported evidence supporting that such macroscopic states cannot be fully described by using only V or Sigma, apart from the number of particles N. In this work, we present an analysis of the fluctuations of these variables that indicates that V and Sigma may be sufficient to define the macroscopic states. Moreover, we show that only one of the invariants of Sigma is necessary, since each component of Sigma falls onto a master curve when plotted as a function of Tr(Sigma). This implies that these granular assemblies have a common shape for the stress tensor, even though it does not correspond to the hydrostatic type. Although most results are obtained by molecular dynamics simulations, we present supporting experimental results.
Fil: Pugnaloni, Luis Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; Argentina
Fil: Damas, Jose. Universidad de Navarra; España
Fil: Zuriguel, Iker. Universidad de Navarra; España
Fil: Maza, Diego. Universidad de Navarra; España