EFFECT OF CRACK MEANDERING ON DYNAMIC, DUCTILE FRACTURE
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Dynamic crack growth is analyzed numerically for a plane strain edge cracked specimen subject to impulsive tensile loading at one end. An elastic-viscoplastic constitutive relation for a porous plastic solid is used to model ductile fracture by the nucleation and subsequent growth of voids to coalescence. Two populations of second-phase particles are represented: large inclusions with low strength, which result in large voids near the crack tip at an early stage, and small second-phase particles, which require large strains before cavities nucleate. Adiabatic heating due to plastic dissipation and the resulting thermal softening are accounted for in the analyses. Various two-dimensional distributions of the larger inclusions in front of the crack tip are considered, while the small second-phase particles are taken to be uniformly distributed. It is found that in most cases cracks grow in a zig-zag manner, dependent on the distribution of larger inclusions. Predictions for the dynamic crack growth behavior and for the time variation of crack tip characterizing parameters are obtained for each case analyzed. The computed crack growth paths and speeds are entirely based on the ductile failure predictions of the material model, so that the present study is free from ad hoc assumptions regarding appropriate dynamic crack growth criteria. 1992 Pergamon Press plc.