Computational micromechanics analysis of cyclic crack-tip behavior for microstructurally small cracks in dual-phase Al-Si alloys
Cracks were simulated to grow through the Al-rich matrix and around silicon particles. The results showed that as the crack approached the particle, the maximum plastic shear strain range at the crack-tip reduced due to the blockage mechanism proposed by microstructural fracture mechanics. However, as the crack advanced even nearer to the particle, the plastic shear strain range increased rapidly. The latter has been interpreted in terms of geometrically necessary dislocation plasticity. Although the crack-tip opening displacement (CTOD) for a long initial crack length was much greater than that of an initially short crack, once both cracks engaged 2-3 silicon particles, the difference in CTOD was reduced; and they followed a common retardation pattern. This phenomenon has been explained by the strong shielding effects of particle clusters on the fatigue crack propagation. These results offered additional insight into commonly observed small crack behavior. © 2001 Elsevier Science Ltd. All rights reserved.
Fan, J; McDowell, DL; Horstemeyer, MF; Gall, K
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