Modeling and parameter identification of granular plastomer conglomerate submitted to internal underpressure

The paper deals with a conglomerate, composed of granular materials encapsulated in a tight, flexible envelope. The structure is submitted to an internal underpressure using a vacuum pump. The underpressure value has a great impact on the behaviour and properties of the medium. The experimental study and the modeling of this phenomenon are investigated in this work. Results of uniaxial tensile tests and characteristic hardening curves are presented for structures filled up with plastic grains. The nonlinear behaviour of such materials is modeled using the viscoplastic constitutive Chaboche’s law, requiring determination of several material parameters. The parameter identification problem is formulated as an optimization task and solved using the evolutionary algorithm. Simulated graphs follow precisely the experimental curves. The proposed methodology can be easily adapted to other constitutive models and experiments.