A finite-deformation constitutive model of particle-binder composites incorporating yield-surface-free plasticity
Résumé
We present a quasi-static constitutive model for particle-binder composites which accounts for finite-deformation kinematics, non-linear elasto-plasticity without apparent yield, cyclic hysteresis and progressive stress-softening before the attainment of stable cyclic response. The model is based on deformation mechanisms experimentally observed during cyclic compression of Plastic-Bonded Explosives (PBX) at large strain. An additive decomposition of strain energy into elastic and inelastic parts is assumed, where the elastic response is modeled using Ogden hyperelasticity while the inelastic response is described using yield-surface-free endochronic plasticity based on the concepts of internal variables and of evolution or rate equations. Stress-softening is modeled using two approaches; a discontinuous isotropic damage model to appropriately describe the softening in the overall loading-unloading response, and a material scale function to describe the progressive cyclic softening until cyclic stabilization. Finally, a nonlin-ear multivariate optimization procedure is developed to estimate the elasto-plastic model parameters from nominal stress-strain experimental cyclic compression data, and a sensitivity analysis is conducted to quantify the influence of these parameters on the cyclic response.
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