Dynamic crack growth in a nonlocal progressively cavitating solid

• Published in: European journal of mechanics, A, Solids Vol. 17; no. 3; pp. 421 - 438
• Main Authors: Needleman, A., Tvergaard, V.
• Format: Journal Article
• Language: English
• Published: Paris Elsevier Masson SAS 01.05.1998; Elsevier
• Subjects: Exact sciences and technology; Fracture mechanics (crack, fatigue, damage...); Fracture mechanics, fatigue and cracks; Fundamental areas of phenomenology (including applications); Physics; Solid mechanics; Structural and continuum mechanics; Constitutive equation; Strain softening; Thermomechanical properties; Numerical method; Cavitation; Porous material; Tension test; Edge crack; Crack propagation; Finite element method; Adiabatic approximation; Elastoplasticity; Precracked specimen; Viscoplasticity; Crack tip; Ductile material; Impact test; Non local theory; Dynamic load; Mechanical shock
• ISSN: 0997-7538; 1873-7285
• DOI: 10.1016/S0997-7538(98)80053-3

Dynamic crack growth is analyzed numerically using a nonlocal constitutive formulation for a porous ductile material. The delocalization relates 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 element computations are carried out 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 computations. The effect of the material characteristic length on the crack growth behavior and on the mesh sensitivity of the results is considered. For comparison purposes, results are also obtained for the corresponding local constitutive relation. The crack growth resistance is found to increase and the crack speed to decrease with increasing values of the material characteristic length. The crack growth predictions using the nonlocal constitutive model exhibit less mesh sensitivity than the corresponding ones based on the local constitutive relation. However, for the largest value of the material characteristic length considered a divergence between predictions based on three discretizations is found at late times.