Fatigue growth of internal flaw: Simulation of subsurface crack penetration to the surface of the structure

In the maintenance code for nuclear power plants, initial defects are modeled as elliptical cracks in a plane normal to the tension loading direction. However, in the S-FEM simulation the defect shape, which is subjected to multi-axial loading, is realistically modeled, and the crack growth due to fatigue can be simulated. The conservativeness of the maintenance code is discussed. Parametric studies are conducted by S-FEM for examination of this problem. A simple new proximity rule was proposed, and the results of this new rule are found to be reasonable and conservative.