Rate-dependent transition from tensile damage to discrete fracture in dynamic brittle failure

Based on the work for a combined damage/plasticity model of geologic materi als and the bifurcation analysis of material failure, an analytical framewo rk is established to study the rate-dependent transition from continuum dam age to discrete fracture in dynamic brittle failure. Because of the simple formulation, a vectorized constitutive model solver can be designed for lar ge-scale computer simulation. A continuum tangent stiffness tenser is invok ed for the tensile damage evolution such that the bifurcation analysis can be performed to identify the initiation and orientation of tensile failure. It is shown that the orientation of tensile failure is rate-independent al though the limit state is rate-dependent for the rate-dependent tensile dam age model. Sample problems are considered to demonstrate the features of th e proposed approach. (C) 2001 Elsevier Science Ltd. All rights reserved.