[SY-K3] Symposium K-3

[SY-K3] Creep of strongly disordered materials: Plasticity, damage and approach to failure

Invited

^○Michael Zaiser, David Fernandez Castellanos (Inst,. of Materials Simulation, Dept of Materials Science, FAU University of Erlangen-Nuremberg, Germany)

Stochastic plasticity models have recently become popular for modelling the deformation behavior of structually disordered materials, from amorphous solids over crystals with disordered microstructure to geomaterials. We generalize such models to account for thermally activated creep processes in conjunction with structural damage. We show that the thus modified models exhibit three-stage creep curves where failure occurs as a finite-time singularity of the creep rate in conjunction with strong localization of deformation in a catastrophic shear band. Deformation occurs as a stochastic sequence of discrete avalanches with a rate that accelerates towards failure in the form of an inverse Omori law. Immediately before failure, the system switches to a regime of mechanical activation where the avalanche statistics exhibits universal features. We compare our findings with experimental data on failure of rock samples and discuss relations with other stochastic models of plasticity and fracture.