Plastic-Energy Dissipation in Pressure-Dependent Materials

Abstract

A thermodynamics-based energy analysis approach for pressure-dependent materials is presented. Formulation of plastic free energy and plastic dissipation for the nonassociated Drucker-Prager plasticity model is derived based on thermodynamics. It is proven that the proposed energy computation formulation always gives nonnegative incremental plastic dissipation, as required by the second law of thermodynamics. The presented methodology is illustrated using numerical simulations of Toyoura sand and Sacramento River sand under different loading conditions. Multidirectional loading and pressure dependency effects on plastic dissipation are investigated. The continuous, nonnegative dissipation of mechanical energy in pressure-dependent frictional materials under complex three-dimensional cyclic loading was properly modeled.