Strain localization criteria for viscoplastic geomaterials

Abstract This work presents a viscoplastic localization criterion to detect quasi‐instantaneous (i.e., load‐induced) and delayed (creep‐induced) strain in rate‐dependent solids. The study is based on the theory of controllability description mechanical response. Analytical precursors unstable states are defined through systems ordinary differential equations (OEDs). use proposed criteria illustrated at material point level set analyses simulating active porous rock. In addition, full‐field finite element simulations compression tests conducted under various pressures reported demonstrate role local viscoplasticity spontaneous propagation deformation bands stationary boundary conditions. shows that maintains negative sign as long behavior unstable, is, rate accelerating. switch coincides with transition decelerating deformation. revealed pulses overstress always emerge correspondence growth behavior, peak matches stable behavior. responses recovered from were consistent those observed predictions presented theory.