MESH EFFECTS IN THE ANALYSIS OF DYNAMIC DUCTILE CRACK-GROWTH
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For numerical studies of dynamic crack growth the mesh sensitivity of the crack growth predictions is investigated. The computed crack growth behavior is based on the ductile fracture predictions of an elastic-viscoplastic constitutive relation for a porous plastic solid, which models the nucleation and growth of voids to coalescence. Both initially sharp and initially blunt cracks are analyzed. 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. For the larger voids the size and spacing are directly specified in the analyses, whereas no length scale is specified for the small-scale voids. Crack growth predictions in cases where the large-scale voids dominate show practically no mesh sensitivity, whereas cases dominated by the small-scale voids show a clear mesh sensitivity. For initially sharp cracks the initiation of crack growth is quite sensitive to the mesh. However, for initially blunt cracks the mesh sensitivity of the initiation time is removed. 1993.
