Dynamic Effective Mass of Granular Media

Chaur-Jian Hsu, David L. Johnson, Rohit A. Ingale, John J. Valenza, Nicolas Gland, Hernán A. Makse
2009 Physical Review Letters  
We develop the concept of frequency dependent effective mass, M(omega), of jammed granular materials which occupy a rigid cavity to a filling fraction of 48%, the remaining volume being air of normal room condition or controlled humidity. The dominant features of M(omega) provide signatures of the dissipation of acoustic modes, elasticity and aging effects in the granular medium. We perform humidity controlled experiments and interpret the data in terms of a continuum model and a "trap" model
more » ... thermally activated capillary bridges at the contact points. The results suggest that attenuation in the granular materials is influenced significantly by the kinetics of capillary condensation between the asperities at the contacts.
doi:10.1103/physrevlett.102.058001 pmid:19257558 fatcat:kr3vdj4tmfcq3grpih3n2a4k24