Modeling of crack tip high inertia zone in dynamic brittle fracture

摘要

A phenomenological cohesive term is proposed and added to an existingcohesive constitutive law (by Roy and Dodds) to model the crack tip high inertia regionproposed by Gao. The new term is attributed to fracture mechanisms that result in highenergy dissipation around the crack tip and is assumed to be a function of externalenergy per volume input into the system. Finite element analysis is performed onPMMA with constant velocity boundary conditions and mesh discretization based on thework of Xu and Needleman. The cohesive model with the proposed dissipative term isonly applied in the high inertia zone i.e., to cohesive elements very close to the crack tipand the traditional Roy and Dodds model is applied on cohesive elements in the rest ofthe domain. It was observed that crack propagated in three phases with a speed of 0.35cRbefore branching, which are in good agreement with experimental observations. Thus,modeling of high inertia zone is one of the key aspects to understanding brittle fracture.