Quasistatic anisotropic induced behaviour of a tatb-based plastic-bonded explosive

The constitutive law of a plastic-bonded explosive (PBX) based on TATB crystals is studied in the quasistatic loading range. The experimental data highlight a viscoelastic behaviour with damage, and an anisotropy induced by plastic flow. The existing models for PBXs being not appropriate, a constitutive law accounting for the observed mechanisms is proposed. The linear viscoelasticity is integrated in a microplane model describing an effective anisotropic damage. A multilayer viscoplasticity is used to yield a non-linear kinematic hardening. A von Mises yield criterion is defined on each surface and a dilatancy function describes the volumetric plastic yield. This law is implemented in the Abaqus/Standard finite element code in the form of a UMAT subroutine. The model is calibrated on ten tests. The simulations performed to compare the model to each experimental test correctly reproduce the behaviour of the studied explosive composition.