The analysis of multiple surface cracks growth behavior under the interaction of creep cracks

The damage model was implemented into user subroutine of commercial ABAQUS code to calculate the damage accumulation in each time interval and to simulate the crack growth. The influence of crack configurations and residual stress on crack growth behavior in the presence of multiple surface cracks were studied through the variation of crack growth rate. With the relative surface crack sizes (a/t, a/c,) become larger and the distance between two cracks (s/c) becomes close, the interaction between two surface cracks were enhanced and the crack growth behavior was improved. Besides, the existence of residual tensile stress also accelerated the crack growth rate. According to the change of crack growth rates, the critical value of γ_creep for combination of multiple creep surface cracks was assumed to be 1.27. As γ_creep ≥ 1.27 two interacting cracks should be considered to combine into a new big crack otherwise they can be treated as isolated cracks, respectively.