DYNAMIC CRACK-GROWTH IN A NONLOCAL PROGRESSIVELY CAVITATING SOLID

Dynamic crack growth is analyzed numerically using a nonlocal constitu tive formulation for a porous ductile material. The delocalization rel ates to the void growth and coalescence mechanism and is incorporated in terms of an integral condition on the rate of increase of the void volume fraction. The material is modeled as elastic-viscoplastic with the thermal softening due to adiabatic heating accounted for. Finite e lement computations are carried our for edge cracked specimens subject to tensile impact loading. Two values of the material characteristic length and two finite-element discretizations are used in most computa tions. The effect of the material characteristic length on the crack g rowth behavior and on the mesh sensitivity of the results is considere d. For comparison purposes, results are also obtained For the correspo nding local constitutive relation. The crack growth resistance is foun d to increase and the crack speed to decrease with increasing values o f the material characteristic length. The crack growth predictions usi ng the nonlocal constitutive model exhibit less mesh sensitivity than the corresponding ones based on the local constitutive relation. Howev er, for the largest value of the material characteristic length consid ered a divergence between predictions based on three discretizations i s found at late times. (C) Elsevier, Paris.