A FINITE STRAIN ELASTIC-PLASTIC MODEL FOR THE QUASI-STATIC BEHAVIOR OF PARTICULATE COMPOSITES

The quasi-static behaviour of a propellant-like material is studied. A Lagrangian finite strain elastic-plastic model is proposed. Employmen t of logarithmic strain is followed by elastic-plastic additive decomp osition. The plastic deformation is split in volumetric and distorsion al parts which constitute two distinct state variables for the compact ion (matrix compressibility) and yielding (aggregate deformation) cons idered as separate mechanisms. A thermodynamic potential generates the rubber-like elastic behaviour. The elastic moduli are assumed to depe nd on plastic volumetric deformation; this is linked to some energy re lease, accounted for in the compaction model. The yielding mechanism i s described by a non-associated flow rule. The model conveys significa nt geometrical and mechanical coupling effects. (C) 1996 Elsevier Scie nce Ltd